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Added backlight support for some samsung laptops #11

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xonatius
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@xonatius xonatius commented Sep 6, 2011

Models:

  • N120
  • R468/R418
  • X320/X420/X520
  • R510/P510
  • N350
  • R470/R420
  • R528/R728
  • SQ1S

Models:
 * N120
 * R468/R418
 * X320/X420/X520
 * R510/P510
 * N350
 * R470/R420
 * R528/R728
 * SQ1S
@torvalds
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torvalds commented Sep 6, 2011

I'm not doing github pulls. The pull requests are seriously
misdesigned, and github does horrible things to the commits.

Please don't press the "pull request" github button. Do proper kernel
pull request with diffstat, git source tree (which can be on github,
of course), branch, commit information etc etc etc.

                  Linus

@xonatius xonatius closed this Sep 7, 2011
@nils-werner
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How are pullrequest seriously misdesigned (apart from that you might be used to a different kind of workflow)?

@valpackett
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I'm not doing linux kernel pulls. The kernel pulls are seriously
misdesigned, and linux does horrible things to the commits.

Please don't press the "pull request" kernel button. Do proper github
pull request with diffstat, git source tree (which can be on linux,
of course), branch, commit information etc etc etc.

GitHub

@tilsammans
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I honestly would like to know why github pull requests are misdesigned. I'll grant that I didn't actually create git but they seem to work just fine, is there something I am missing?

@hotwoofy
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hotwoofy commented Sep 7, 2011

@nils-werner
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See https://github.com/torvalds/diveclog/pull/18#issuecomment-2023552

Wow, great discussion went on there. Shacon raised perfectly valid points and Torvalds was basically "f this, I don't care, you're crazy". Great response!

@torvalds
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torvalds commented Sep 9, 2011

On Fri, Sep 9, 2011 at 12:49 AM, Nils Werner
[email protected]
wrote:

Wow, great discussion went on there. Shacon raised perfectly valid points and Torvalds was basically "f this, I don't care, you're crazy". Great response!

Can you read?

"If the merge message doesn't tell me who the merge is from and what
branch it was, the merge message is totally useless."

If you can't understand that, then yes, you're crazy. Or just terminally stupid.

The quality of github "issues" and comments really is very low. This
being just another example of it.

                          Linus

@nils-werner
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First, I agree with Scott: In many cases people delete their fork (or at least the branch). So where would the message point you to? The pull request of the pulling repository will much more likely be around for a long time.

Also, what if the branch you'll pull from has changed in the meantime? You'd end up with changes that are not documented in the pull request and thus not reviewed by the ones discussing the pull request. As soon as the PR is posted you must put them out of reach of the author to keep them from sneaking in changes.

Great response!

Can you read?

Also, you did notice that you've proven my point right there, right?

@torvalds
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torvalds commented Sep 9, 2011

On Fri, Sep 9, 2011 at 12:10 PM, Nils Werner
[email protected]
wrote:

First, I agree with Scott: In many cases people delete their fork (or at least the branch). So where would the message point you to? The pull request of the pulling repository will much more likely be around for a long time.

That's a "implementation problem". It's not an argument for doing crap.

Simple solution: if people delete the branch or repository, consider
the pull request dead.

You can make the "pull request" namespace separate from the branch
namespace, but do it on the source side, instead of on the
destination side like you do now. So if somebody says "please pull by
branch xyzzy", you turn it into a pull request for

git pull git://github.com/ pull/xyzzy

and then if there i a previous pull request, add a number to it (so it
becomes "pull/xyzzy-2" or whatever).

Or something along those lines. The important part is that YOU MUST
NOT THROW AWAY THE SOURCE INFORMATION!

Also, what if the branch you'll pull from has changed in the meantime?

We actually do this in the kernel on purpose sometimes - people fix up
their stuff.

That said, again, you could do the same thing: if somebody changes a
branch after created a pull request off it, just invalidate the pull
request and refuse to honor it. Again, if you do a separate
"pull/xyzzy" namespace, you should be able to validate that trivially
(save off the commit ID at the time of the pull, and refuse to serve
"pull/xyzzy" if the commit ID doesn't match the branch "xyzzy" any
more).

You'd end up with changes that are not documented in the pull request and thus not reviewed by the ones discussing the pull request.

Umm, considering that the pull requests used to have no documentation
what-so-ever before I even complained about it, that's a pretty damn
weak argument, isn't it?

As soon as the PR is posted you must put them out of reach of the
author to keep them from sneaking in changes.

Can you read?

Also, you did notice that you've proven my point right there, right?

Umm. I'm not polite. Big news. I'd rather be acerbic than stupid.

                       Linus

@nils-werner
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That's a "implementation problem".

A decentralized system that doesn't accept disappearing nodes sounds more like a design problem.

Simple solution: if people delete the branch or repository, consider the pull request dead.

Years after the branch has been merged? Is that a problem we wanted to solve?

Also, what if the branch you'll pull from has changed in the meantime?

We actually do this in the kernel on purpose sometimes - people fix up their stuff.

I meant malicuous changes. Hierarchies are shallow, elite circles basically nonexistant so that's a real issue. And the biggest strength of GitHub.

save off the commit ID at the time of the pull, and refuse to serve "pull/xyzzy" if the commit ID doesn't match the branch "xyzzy" any more

Thats the first constructive comment to this discussion. And sounds like a good idea, apart from the problem that you'd lose the link to the PR wich, to many, is more useful than being able to immediately recognise the source.

Also it would probably require lots of modifications to the deamon though.And very disciplined contributors (always make sure to use dead-end topic-branches, not everybody does that). Separating the two simply improves the workflow a lot.

It'd be interesting what @schacon has to say about it.

Umm, considering that the pull requests used to have no documentation what-so-ever before I even complained about it, that's a pretty damn weak argument, isn't it?

When was that? Months ago? I am talking about your comment 2 days ago.

@nils-werner
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Umm. I'm not polite. Big news. I'd rather be acerbic than stupid.

A personal, unrelated note: Being unable to lead an objective discussion. Judging people, then insulting them just to prove a point. Recognising ones flaws but being unwilling to change them, instead bragging about them. Missing the ability to reflect on ones actions during interactions with others.

That sounds pretty stupid to me. Anyways, I'm moving on.

@jeffWelling
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@nils-werner

A decentralized system that doesn't accept disappearing nodes sounds more like a design problem.

I thought we were talking about pull requests and branches? When did a branch become a node?
Perhaps I'm missing something but this sounds simple; if you have a change and you want someone else to pull it, it sounds reasonable to expect you to keep the change published at least until it is pulled.

I meant malicuous changes. Hierarchies are shallow, elite circles basically nonexistant so that's a real issue. And the biggest strength of GitHub.

Except that, as indicated by Scott Chacon [0], the most common scenario is to perform the pull request locally on your machine, allowing you to pull the code and then review it without said code being changed before merging. I can understand your argument in relation to pull requests done using the button on the website though.

[0] https://github.com/torvalds/diveclog/pull/18

cuviper pushed a commit to cuviper/linux-uprobes that referenced this pull request Nov 3, 2011
* Ingo Molnar <[email protected]> wrote:

> The patch below addresses these concerns, serializes the output, tidies up the
> printout, resulting in this new output:

There's one bug remaining that my patch does not address: the vCPUs are not
printed in order:

# vCPU #0's dump:
# vCPU #2's dump:
# vCPU torvalds#24's dump:
# vCPU #5's dump:
# vCPU torvalds#39's dump:
# vCPU torvalds#38's dump:
# vCPU torvalds#51's dump:
# vCPU torvalds#11's dump:
# vCPU torvalds#10's dump:
# vCPU torvalds#12's dump:

This is undesirable as the order of printout is highly random, so successive
dumps are difficult to compare.

The patch below serializes the signalling itself. (this is on top of the
previous patch)

The patch also tweaks the vCPU printout line a bit so that it does not start
with '#', which is discarded if such messages are pasted into Git commit
messages.

Signed-off-by: Ingo Molnar <[email protected]>
Signed-off-by: Pekka Enberg <[email protected]>
torvalds pushed a commit that referenced this pull request Dec 15, 2011
If the pte mapping in generic_perform_write() is unmapped between
iov_iter_fault_in_readable() and iov_iter_copy_from_user_atomic(), the
"copied" parameter to ->end_write can be zero. ext4 couldn't cope with
it with delayed allocations enabled. This skips the i_disksize
enlargement logic if copied is zero and no new data was appeneded to
the inode.

 gdb> bt
 #0  0xffffffff811afe80 in ext4_da_should_update_i_disksize (file=0xffff88003f606a80, mapping=0xffff88001d3824e0, pos=0x1\
 08000, len=0x1000, copied=0x0, page=0xffffea0000d792e8, fsdata=0x0) at fs/ext4/inode.c:2467
 #1  ext4_da_write_end (file=0xffff88003f606a80, mapping=0xffff88001d3824e0, pos=0x108000, len=0x1000, copied=0x0, page=0\
 xffffea0000d792e8, fsdata=0x0) at fs/ext4/inode.c:2512
 #2  0xffffffff810d97f1 in generic_perform_write (iocb=<value optimized out>, iov=<value optimized out>, nr_segs=<value o\
 ptimized out>, pos=0x108000, ppos=0xffff88001e26be40, count=<value optimized out>, written=0x0) at mm/filemap.c:2440
 #3  generic_file_buffered_write (iocb=<value optimized out>, iov=<value optimized out>, nr_segs=<value optimized out>, p\
 os=0x108000, ppos=0xffff88001e26be40, count=<value optimized out>, written=0x0) at mm/filemap.c:2482
 #4  0xffffffff810db5d1 in __generic_file_aio_write (iocb=0xffff88001e26bde8, iov=0xffff88001e26bec8, nr_segs=0x1, ppos=0\
 xffff88001e26be40) at mm/filemap.c:2600
 #5  0xffffffff810db853 in generic_file_aio_write (iocb=0xffff88001e26bde8, iov=0xffff88001e26bec8, nr_segs=<value optimi\
 zed out>, pos=<value optimized out>) at mm/filemap.c:2632
 #6  0xffffffff811a71aa in ext4_file_write (iocb=0xffff88001e26bde8, iov=0xffff88001e26bec8, nr_segs=0x1, pos=0x108000) a\
 t fs/ext4/file.c:136
 #7  0xffffffff811375aa in do_sync_write (filp=0xffff88003f606a80, buf=<value optimized out>, len=<value optimized out>, \
 ppos=0xffff88001e26bf48) at fs/read_write.c:406
 #8  0xffffffff81137e56 in vfs_write (file=0xffff88003f606a80, buf=0x1ec2960 <Address 0x1ec2960 out of bounds>, count=0x4\
 000, pos=0xffff88001e26bf48) at fs/read_write.c:435
 #9  0xffffffff8113816c in sys_write (fd=<value optimized out>, buf=0x1ec2960 <Address 0x1ec2960 out of bounds>, count=0x\
 4000) at fs/read_write.c:487
 #10 <signal handler called>
 #11 0x00007f120077a390 in __brk_reservation_fn_dmi_alloc__ ()
 #12 0x0000000000000000 in ?? ()
 gdb> print offset
 $22 = 0xffffffffffffffff
 gdb> print idx
 $23 = 0xffffffff
 gdb> print inode->i_blkbits
 $24 = 0xc
 gdb> up
 #1  ext4_da_write_end (file=0xffff88003f606a80, mapping=0xffff88001d3824e0, pos=0x108000, len=0x1000, copied=0x0, page=0\
 xffffea0000d792e8, fsdata=0x0) at fs/ext4/inode.c:2512
 2512                    if (ext4_da_should_update_i_disksize(page, end)) {
 gdb> print start
 $25 = 0x0
 gdb> print end
 $26 = 0xffffffffffffffff
 gdb> print pos
 $27 = 0x108000
 gdb> print new_i_size
 $28 = 0x108000
 gdb> print ((struct ext4_inode_info *)((char *)inode-((int)(&((struct ext4_inode_info *)0)->vfs_inode))))->i_disksize
 $29 = 0xd9000
 gdb> down
 2467            for (i = 0; i < idx; i++)
 gdb> print i
 $30 = 0xd44acbee

This is 100% reproducible with some autonuma development code tuned in
a very aggressive manner (not normal way even for knumad) which does
"exotic" changes to the ptes. It wouldn't normally trigger but I don't
see why it can't happen normally if the page is added to swap cache in
between the two faults leading to "copied" being zero (which then
hangs in ext4). So it should be fixed. Especially possible with lumpy
reclaim (albeit disabled if compaction is enabled) as that would
ignore the young bits in the ptes.

Signed-off-by: Andrea Arcangeli <[email protected]>
Signed-off-by: "Theodore Ts'o" <[email protected]>
Cc: [email protected]
jkstrick pushed a commit to jkstrick/linux that referenced this pull request Feb 11, 2012
If the netdev is already in NETREG_UNREGISTERING/_UNREGISTERED state, do not
update the real num tx queues. netdev_queue_update_kobjects() is already
called via remove_queue_kobjects() at NETREG_UNREGISTERING time. So, when
upper layer driver, e.g., FCoE protocol stack is monitoring the netdev
event of NETDEV_UNREGISTER and calls back to LLD ndo_fcoe_disable() to remove
extra queues allocated for FCoE, the associated txq sysfs kobjects are already
removed, and trying to update the real num queues would cause something like
below:

...
PID: 25138  TASK: ffff88021e64c440  CPU: 3   COMMAND: "kworker/3:3"
 #0 [ffff88021f007760] machine_kexec at ffffffff810226d9
 #1 [ffff88021f0077d0] crash_kexec at ffffffff81089d2d
 #2 [ffff88021f0078a0] oops_end at ffffffff813bca78
 #3 [ffff88021f0078d0] no_context at ffffffff81029e72
 #4 [ffff88021f007920] __bad_area_nosemaphore at ffffffff8102a155
 #5 [ffff88021f0079f0] bad_area_nosemaphore at ffffffff8102a23e
 torvalds#6 [ffff88021f007a00] do_page_fault at ffffffff813bf32e
 torvalds#7 [ffff88021f007b10] page_fault at ffffffff813bc045
    [exception RIP: sysfs_find_dirent+17]
    RIP: ffffffff81178611  RSP: ffff88021f007bc0  RFLAGS: 00010246
    RAX: ffff88021e64c440  RBX: ffffffff8156cc63  RCX: 0000000000000004
    RDX: ffffffff8156cc63  RSI: 0000000000000000  RDI: 0000000000000000
    RBP: ffff88021f007be0   R8: 0000000000000004   R9: 0000000000000008
    R10: ffffffff816fed00  R11: 0000000000000004  R12: 0000000000000000
    R13: ffffffff8156cc63  R14: 0000000000000000  R15: ffff8802222a0000
    ORIG_RAX: ffffffffffffffff  CS: 0010  SS: 0018
 torvalds#8 [ffff88021f007be8] sysfs_get_dirent at ffffffff81178c07
 torvalds#9 [ffff88021f007c18] sysfs_remove_group at ffffffff8117ac27
torvalds#10 [ffff88021f007c48] netdev_queue_update_kobjects at ffffffff813178f9
torvalds#11 [ffff88021f007c88] netif_set_real_num_tx_queues at ffffffff81303e38
torvalds#12 [ffff88021f007cc8] ixgbe_set_num_queues at ffffffffa0249763 [ixgbe]
torvalds#13 [ffff88021f007cf8] ixgbe_init_interrupt_scheme at ffffffffa024ea89 [ixgbe]
torvalds#14 [ffff88021f007d48] ixgbe_fcoe_disable at ffffffffa0267113 [ixgbe]
torvalds#15 [ffff88021f007d68] vlan_dev_fcoe_disable at ffffffffa014fef5 [8021q]
torvalds#16 [ffff88021f007d78] fcoe_interface_cleanup at ffffffffa02b7dfd [fcoe]
torvalds#17 [ffff88021f007df8] fcoe_destroy_work at ffffffffa02b7f08 [fcoe]
torvalds#18 [ffff88021f007e18] process_one_work at ffffffff8105d7ca
torvalds#19 [ffff88021f007e68] worker_thread at ffffffff81060513
torvalds#20 [ffff88021f007ee8] kthread at ffffffff810648b6
torvalds#21 [ffff88021f007f48] kernel_thread_helper at ffffffff813c40f4

Signed-off-by: Yi Zou <[email protected]>
Tested-by: Ross Brattain <[email protected]>
Tested-by: Stephen Ko <[email protected]>
Signed-off-by: Jeff Kirsher <[email protected]>
zachariasmaladroit pushed a commit to galaxys-cm7miui-kernel/linux that referenced this pull request Feb 11, 2012
If the netdev is already in NETREG_UNREGISTERING/_UNREGISTERED state, do not
update the real num tx queues. netdev_queue_update_kobjects() is already
called via remove_queue_kobjects() at NETREG_UNREGISTERING time. So, when
upper layer driver, e.g., FCoE protocol stack is monitoring the netdev
event of NETDEV_UNREGISTER and calls back to LLD ndo_fcoe_disable() to remove
extra queues allocated for FCoE, the associated txq sysfs kobjects are already
removed, and trying to update the real num queues would cause something like
below:

...
PID: 25138  TASK: ffff88021e64c440  CPU: 3   COMMAND: "kworker/3:3"
 #0 [ffff88021f007760] machine_kexec at ffffffff810226d9
 #1 [ffff88021f0077d0] crash_kexec at ffffffff81089d2d
 #2 [ffff88021f0078a0] oops_end at ffffffff813bca78
 #3 [ffff88021f0078d0] no_context at ffffffff81029e72
 #4 [ffff88021f007920] __bad_area_nosemaphore at ffffffff8102a155
 #5 [ffff88021f0079f0] bad_area_nosemaphore at ffffffff8102a23e
 torvalds#6 [ffff88021f007a00] do_page_fault at ffffffff813bf32e
 torvalds#7 [ffff88021f007b10] page_fault at ffffffff813bc045
    [exception RIP: sysfs_find_dirent+17]
    RIP: ffffffff81178611  RSP: ffff88021f007bc0  RFLAGS: 00010246
    RAX: ffff88021e64c440  RBX: ffffffff8156cc63  RCX: 0000000000000004
    RDX: ffffffff8156cc63  RSI: 0000000000000000  RDI: 0000000000000000
    RBP: ffff88021f007be0   R8: 0000000000000004   R9: 0000000000000008
    R10: ffffffff816fed00  R11: 0000000000000004  R12: 0000000000000000
    R13: ffffffff8156cc63  R14: 0000000000000000  R15: ffff8802222a0000
    ORIG_RAX: ffffffffffffffff  CS: 0010  SS: 0018
 torvalds#8 [ffff88021f007be8] sysfs_get_dirent at ffffffff81178c07
 torvalds#9 [ffff88021f007c18] sysfs_remove_group at ffffffff8117ac27
torvalds#10 [ffff88021f007c48] netdev_queue_update_kobjects at ffffffff813178f9
torvalds#11 [ffff88021f007c88] netif_set_real_num_tx_queues at ffffffff81303e38
torvalds#12 [ffff88021f007cc8] ixgbe_set_num_queues at ffffffffa0249763 [ixgbe]
torvalds#13 [ffff88021f007cf8] ixgbe_init_interrupt_scheme at ffffffffa024ea89 [ixgbe]
torvalds#14 [ffff88021f007d48] ixgbe_fcoe_disable at ffffffffa0267113 [ixgbe]
torvalds#15 [ffff88021f007d68] vlan_dev_fcoe_disable at ffffffffa014fef5 [8021q]
torvalds#16 [ffff88021f007d78] fcoe_interface_cleanup at ffffffffa02b7dfd [fcoe]
torvalds#17 [ffff88021f007df8] fcoe_destroy_work at ffffffffa02b7f08 [fcoe]
torvalds#18 [ffff88021f007e18] process_one_work at ffffffff8105d7ca
torvalds#19 [ffff88021f007e68] worker_thread at ffffffff81060513
torvalds#20 [ffff88021f007ee8] kthread at ffffffff810648b6
torvalds#21 [ffff88021f007f48] kernel_thread_helper at ffffffff813c40f4

Signed-off-by: Yi Zou <[email protected]>
Tested-by: Ross Brattain <[email protected]>
Tested-by: Stephen Ko <[email protected]>
Signed-off-by: Jeff Kirsher <[email protected]>
tworaz pushed a commit to tworaz/linux that referenced this pull request Feb 13, 2012
…S block during isolation for migration

commit 0bf380b upstream.

When isolating for migration, migration starts at the start of a zone
which is not necessarily pageblock aligned.  Further, it stops isolating
when COMPACT_CLUSTER_MAX pages are isolated so migrate_pfn is generally
not aligned.  This allows isolate_migratepages() to call pfn_to_page() on
an invalid PFN which can result in a crash.  This was originally reported
against a 3.0-based kernel with the following trace in a crash dump.

PID: 9902   TASK: d47aecd0  CPU: 0   COMMAND: "memcg_process_s"
 #0 [d72d3ad0] crash_kexec at c028cfdb
 #1 [d72d3b24] oops_end at c05c5322
 #2 [d72d3b38] __bad_area_nosemaphore at c0227e60
 #3 [d72d3bec] bad_area at c0227fb6
 #4 [d72d3c00] do_page_fault at c05c72ec
 #5 [d72d3c80] error_code (via page_fault) at c05c47a4
    EAX: 00000000  EBX: 000c0000  ECX: 00000001  EDX: 00000807  EBP: 000c0000
    DS:  007b      ESI: 00000001  ES:  007b      EDI: f3000a80  GS:  6f50
    CS:  0060      EIP: c030b15a  ERR: ffffffff  EFLAGS: 00010002
 torvalds#6 [d72d3cb4] isolate_migratepages at c030b15a
 torvalds#7 [d72d3d1] zone_watermark_ok at c02d26cb
 torvalds#8 [d72d3d2c] compact_zone at c030b8de
 torvalds#9 [d72d3d68] compact_zone_order at c030bba1
torvalds#10 [d72d3db4] try_to_compact_pages at c030bc84
torvalds#11 [d72d3ddc] __alloc_pages_direct_compact at c02d61e7
torvalds#12 [d72d3e08] __alloc_pages_slowpath at c02d66c7
torvalds#13 [d72d3e78] __alloc_pages_nodemask at c02d6a97
torvalds#14 [d72d3eb8] alloc_pages_vma at c030a845
torvalds#15 [d72d3ed4] do_huge_pmd_anonymous_page at c03178eb
torvalds#16 [d72d3f00] handle_mm_fault at c02f36c6
torvalds#17 [d72d3f30] do_page_fault at c05c70ed
torvalds#18 [d72d3fb0] error_code (via page_fault) at c05c47a4
    EAX: b71ff000  EBX: 00000001  ECX: 00001600  EDX: 00000431
    DS:  007b      ESI: 08048950  ES:  007b      EDI: bfaa3788
    SS:  007b      ESP: bfaa36e0  EBP: bfaa3828  GS:  6f50
    CS:  0073      EIP: 080487c8  ERR: ffffffff  EFLAGS: 00010202

It was also reported by Herbert van den Bergh against 3.1-based kernel
with the following snippet from the console log.

BUG: unable to handle kernel paging request at 01c00008
IP: [<c0522399>] isolate_migratepages+0x119/0x390
*pdpt = 000000002f7ce001 *pde = 0000000000000000

It is expected that it also affects 3.2.x and current mainline.

The problem is that pfn_valid is only called on the first PFN being
checked and that PFN is not necessarily aligned.  Lets say we have a case
like this

H = MAX_ORDER_NR_PAGES boundary
| = pageblock boundary
m = cc->migrate_pfn
f = cc->free_pfn
o = memory hole

H------|------H------|----m-Hoooooo|ooooooH-f----|------H

The migrate_pfn is just below a memory hole and the free scanner is beyond
the hole.  When isolate_migratepages started, it scans from migrate_pfn to
migrate_pfn+pageblock_nr_pages which is now in a memory hole.  It checks
pfn_valid() on the first PFN but then scans into the hole where there are
not necessarily valid struct pages.

This patch ensures that isolate_migratepages calls pfn_valid when
necessary.

Reported-by: Herbert van den Bergh <[email protected]>
Tested-by: Herbert van den Bergh <[email protected]>
Signed-off-by: Mel Gorman <[email protected]>
Acked-by: Michal Nazarewicz <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
xXorAa pushed a commit to xXorAa/linux that referenced this pull request Feb 17, 2012
…S block during isolation for migration

commit 0bf380b upstream.

When isolating for migration, migration starts at the start of a zone
which is not necessarily pageblock aligned.  Further, it stops isolating
when COMPACT_CLUSTER_MAX pages are isolated so migrate_pfn is generally
not aligned.  This allows isolate_migratepages() to call pfn_to_page() on
an invalid PFN which can result in a crash.  This was originally reported
against a 3.0-based kernel with the following trace in a crash dump.

PID: 9902   TASK: d47aecd0  CPU: 0   COMMAND: "memcg_process_s"
 #0 [d72d3ad0] crash_kexec at c028cfdb
 #1 [d72d3b24] oops_end at c05c5322
 #2 [d72d3b38] __bad_area_nosemaphore at c0227e60
 #3 [d72d3bec] bad_area at c0227fb6
 #4 [d72d3c00] do_page_fault at c05c72ec
 #5 [d72d3c80] error_code (via page_fault) at c05c47a4
    EAX: 00000000  EBX: 000c0000  ECX: 00000001  EDX: 00000807  EBP: 000c0000
    DS:  007b      ESI: 00000001  ES:  007b      EDI: f3000a80  GS:  6f50
    CS:  0060      EIP: c030b15a  ERR: ffffffff  EFLAGS: 00010002
 torvalds#6 [d72d3cb4] isolate_migratepages at c030b15a
 torvalds#7 [d72d3d1] zone_watermark_ok at c02d26cb
 torvalds#8 [d72d3d2c] compact_zone at c030b8de
 torvalds#9 [d72d3d68] compact_zone_order at c030bba1
torvalds#10 [d72d3db4] try_to_compact_pages at c030bc84
torvalds#11 [d72d3ddc] __alloc_pages_direct_compact at c02d61e7
torvalds#12 [d72d3e08] __alloc_pages_slowpath at c02d66c7
torvalds#13 [d72d3e78] __alloc_pages_nodemask at c02d6a97
torvalds#14 [d72d3eb8] alloc_pages_vma at c030a845
torvalds#15 [d72d3ed4] do_huge_pmd_anonymous_page at c03178eb
torvalds#16 [d72d3f00] handle_mm_fault at c02f36c6
torvalds#17 [d72d3f30] do_page_fault at c05c70ed
torvalds#18 [d72d3fb0] error_code (via page_fault) at c05c47a4
    EAX: b71ff000  EBX: 00000001  ECX: 00001600  EDX: 00000431
    DS:  007b      ESI: 08048950  ES:  007b      EDI: bfaa3788
    SS:  007b      ESP: bfaa36e0  EBP: bfaa3828  GS:  6f50
    CS:  0073      EIP: 080487c8  ERR: ffffffff  EFLAGS: 00010202

It was also reported by Herbert van den Bergh against 3.1-based kernel
with the following snippet from the console log.

BUG: unable to handle kernel paging request at 01c00008
IP: [<c0522399>] isolate_migratepages+0x119/0x390
*pdpt = 000000002f7ce001 *pde = 0000000000000000

It is expected that it also affects 3.2.x and current mainline.

The problem is that pfn_valid is only called on the first PFN being
checked and that PFN is not necessarily aligned.  Lets say we have a case
like this

H = MAX_ORDER_NR_PAGES boundary
| = pageblock boundary
m = cc->migrate_pfn
f = cc->free_pfn
o = memory hole

H------|------H------|----m-Hoooooo|ooooooH-f----|------H

The migrate_pfn is just below a memory hole and the free scanner is beyond
the hole.  When isolate_migratepages started, it scans from migrate_pfn to
migrate_pfn+pageblock_nr_pages which is now in a memory hole.  It checks
pfn_valid() on the first PFN but then scans into the hole where there are
not necessarily valid struct pages.

This patch ensures that isolate_migratepages calls pfn_valid when
necessary.

Reported-by: Herbert van den Bergh <[email protected]>
Tested-by: Herbert van den Bergh <[email protected]>
Signed-off-by: Mel Gorman <[email protected]>
Acked-by: Michal Nazarewicz <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
koct9i pushed a commit to koct9i/linux that referenced this pull request Feb 20, 2012
fixed:
WARNING: please, no space before tabs
torvalds#11: FILE: adt7411.c:11:
+ * ^I  use power-down mode for suspend?, interrupt handling?$

not fixed as all other macros around it are the same structure and this one is only 2 chars longer:
WARNING: line over 80 characters
torvalds#229: FILE: adt7411.c:229:
+static ADT7411_BIT_ATTR(fast_sampling, ADT7411_REG_CFG3, ADT7411_CFG3_ADC_CLK_225);

Signed-off-by: Frans Meulenbroeks <[email protected]>
Signed-off-by: Guenter Roeck <[email protected]>
koenkooi pushed a commit to koenkooi/linux that referenced this pull request Feb 23, 2012
…S block during isolation for migration

commit 0bf380b upstream.

When isolating for migration, migration starts at the start of a zone
which is not necessarily pageblock aligned.  Further, it stops isolating
when COMPACT_CLUSTER_MAX pages are isolated so migrate_pfn is generally
not aligned.  This allows isolate_migratepages() to call pfn_to_page() on
an invalid PFN which can result in a crash.  This was originally reported
against a 3.0-based kernel with the following trace in a crash dump.

PID: 9902   TASK: d47aecd0  CPU: 0   COMMAND: "memcg_process_s"
 #0 [d72d3ad0] crash_kexec at c028cfdb
 #1 [d72d3b24] oops_end at c05c5322
 #2 [d72d3b38] __bad_area_nosemaphore at c0227e60
 #3 [d72d3bec] bad_area at c0227fb6
 #4 [d72d3c00] do_page_fault at c05c72ec
 #5 [d72d3c80] error_code (via page_fault) at c05c47a4
    EAX: 00000000  EBX: 000c0000  ECX: 00000001  EDX: 00000807  EBP: 000c0000
    DS:  007b      ESI: 00000001  ES:  007b      EDI: f3000a80  GS:  6f50
    CS:  0060      EIP: c030b15a  ERR: ffffffff  EFLAGS: 00010002
 #6 [d72d3cb4] isolate_migratepages at c030b15a
 #7 [d72d3d1] zone_watermark_ok at c02d26cb
 #8 [d72d3d2c] compact_zone at c030b8de
 #9 [d72d3d68] compact_zone_order at c030bba1
torvalds#10 [d72d3db4] try_to_compact_pages at c030bc84
torvalds#11 [d72d3ddc] __alloc_pages_direct_compact at c02d61e7
torvalds#12 [d72d3e08] __alloc_pages_slowpath at c02d66c7
torvalds#13 [d72d3e78] __alloc_pages_nodemask at c02d6a97
torvalds#14 [d72d3eb8] alloc_pages_vma at c030a845
torvalds#15 [d72d3ed4] do_huge_pmd_anonymous_page at c03178eb
torvalds#16 [d72d3f00] handle_mm_fault at c02f36c6
torvalds#17 [d72d3f30] do_page_fault at c05c70ed
torvalds#18 [d72d3fb0] error_code (via page_fault) at c05c47a4
    EAX: b71ff000  EBX: 00000001  ECX: 00001600  EDX: 00000431
    DS:  007b      ESI: 08048950  ES:  007b      EDI: bfaa3788
    SS:  007b      ESP: bfaa36e0  EBP: bfaa3828  GS:  6f50
    CS:  0073      EIP: 080487c8  ERR: ffffffff  EFLAGS: 00010202

It was also reported by Herbert van den Bergh against 3.1-based kernel
with the following snippet from the console log.

BUG: unable to handle kernel paging request at 01c00008
IP: [<c0522399>] isolate_migratepages+0x119/0x390
*pdpt = 000000002f7ce001 *pde = 0000000000000000

It is expected that it also affects 3.2.x and current mainline.

The problem is that pfn_valid is only called on the first PFN being
checked and that PFN is not necessarily aligned.  Lets say we have a case
like this

H = MAX_ORDER_NR_PAGES boundary
| = pageblock boundary
m = cc->migrate_pfn
f = cc->free_pfn
o = memory hole

H------|------H------|----m-Hoooooo|ooooooH-f----|------H

The migrate_pfn is just below a memory hole and the free scanner is beyond
the hole.  When isolate_migratepages started, it scans from migrate_pfn to
migrate_pfn+pageblock_nr_pages which is now in a memory hole.  It checks
pfn_valid() on the first PFN but then scans into the hole where there are
not necessarily valid struct pages.

This patch ensures that isolate_migratepages calls pfn_valid when
necessary.

Reported-by: Herbert van den Bergh <[email protected]>
Tested-by: Herbert van den Bergh <[email protected]>
Signed-off-by: Mel Gorman <[email protected]>
Acked-by: Michal Nazarewicz <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
koenkooi pushed a commit to koenkooi/linux that referenced this pull request Mar 1, 2012
…S block during isolation for migration

commit 0bf380b upstream.

When isolating for migration, migration starts at the start of a zone
which is not necessarily pageblock aligned.  Further, it stops isolating
when COMPACT_CLUSTER_MAX pages are isolated so migrate_pfn is generally
not aligned.  This allows isolate_migratepages() to call pfn_to_page() on
an invalid PFN which can result in a crash.  This was originally reported
against a 3.0-based kernel with the following trace in a crash dump.

PID: 9902   TASK: d47aecd0  CPU: 0   COMMAND: "memcg_process_s"
 #0 [d72d3ad0] crash_kexec at c028cfdb
 #1 [d72d3b24] oops_end at c05c5322
 #2 [d72d3b38] __bad_area_nosemaphore at c0227e60
 #3 [d72d3bec] bad_area at c0227fb6
 #4 [d72d3c00] do_page_fault at c05c72ec
 #5 [d72d3c80] error_code (via page_fault) at c05c47a4
    EAX: 00000000  EBX: 000c0000  ECX: 00000001  EDX: 00000807  EBP: 000c0000
    DS:  007b      ESI: 00000001  ES:  007b      EDI: f3000a80  GS:  6f50
    CS:  0060      EIP: c030b15a  ERR: ffffffff  EFLAGS: 00010002
 #6 [d72d3cb4] isolate_migratepages at c030b15a
 #7 [d72d3d1] zone_watermark_ok at c02d26cb
 #8 [d72d3d2c] compact_zone at c030b8de
 #9 [d72d3d68] compact_zone_order at c030bba1
torvalds#10 [d72d3db4] try_to_compact_pages at c030bc84
torvalds#11 [d72d3ddc] __alloc_pages_direct_compact at c02d61e7
torvalds#12 [d72d3e08] __alloc_pages_slowpath at c02d66c7
torvalds#13 [d72d3e78] __alloc_pages_nodemask at c02d6a97
torvalds#14 [d72d3eb8] alloc_pages_vma at c030a845
torvalds#15 [d72d3ed4] do_huge_pmd_anonymous_page at c03178eb
torvalds#16 [d72d3f00] handle_mm_fault at c02f36c6
torvalds#17 [d72d3f30] do_page_fault at c05c70ed
torvalds#18 [d72d3fb0] error_code (via page_fault) at c05c47a4
    EAX: b71ff000  EBX: 00000001  ECX: 00001600  EDX: 00000431
    DS:  007b      ESI: 08048950  ES:  007b      EDI: bfaa3788
    SS:  007b      ESP: bfaa36e0  EBP: bfaa3828  GS:  6f50
    CS:  0073      EIP: 080487c8  ERR: ffffffff  EFLAGS: 00010202

It was also reported by Herbert van den Bergh against 3.1-based kernel
with the following snippet from the console log.

BUG: unable to handle kernel paging request at 01c00008
IP: [<c0522399>] isolate_migratepages+0x119/0x390
*pdpt = 000000002f7ce001 *pde = 0000000000000000

It is expected that it also affects 3.2.x and current mainline.

The problem is that pfn_valid is only called on the first PFN being
checked and that PFN is not necessarily aligned.  Lets say we have a case
like this

H = MAX_ORDER_NR_PAGES boundary
| = pageblock boundary
m = cc->migrate_pfn
f = cc->free_pfn
o = memory hole

H------|------H------|----m-Hoooooo|ooooooH-f----|------H

The migrate_pfn is just below a memory hole and the free scanner is beyond
the hole.  When isolate_migratepages started, it scans from migrate_pfn to
migrate_pfn+pageblock_nr_pages which is now in a memory hole.  It checks
pfn_valid() on the first PFN but then scans into the hole where there are
not necessarily valid struct pages.

This patch ensures that isolate_migratepages calls pfn_valid when
necessary.

Reported-by: Herbert van den Bergh <[email protected]>
Tested-by: Herbert van den Bergh <[email protected]>
Signed-off-by: Mel Gorman <[email protected]>
Acked-by: Michal Nazarewicz <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
koenkooi pushed a commit to koenkooi/linux that referenced this pull request Mar 19, 2012
…S block during isolation for migration

commit 0bf380b upstream.

When isolating for migration, migration starts at the start of a zone
which is not necessarily pageblock aligned.  Further, it stops isolating
when COMPACT_CLUSTER_MAX pages are isolated so migrate_pfn is generally
not aligned.  This allows isolate_migratepages() to call pfn_to_page() on
an invalid PFN which can result in a crash.  This was originally reported
against a 3.0-based kernel with the following trace in a crash dump.

PID: 9902   TASK: d47aecd0  CPU: 0   COMMAND: "memcg_process_s"
 #0 [d72d3ad0] crash_kexec at c028cfdb
 #1 [d72d3b24] oops_end at c05c5322
 #2 [d72d3b38] __bad_area_nosemaphore at c0227e60
 #3 [d72d3bec] bad_area at c0227fb6
 #4 [d72d3c00] do_page_fault at c05c72ec
 #5 [d72d3c80] error_code (via page_fault) at c05c47a4
    EAX: 00000000  EBX: 000c0000  ECX: 00000001  EDX: 00000807  EBP: 000c0000
    DS:  007b      ESI: 00000001  ES:  007b      EDI: f3000a80  GS:  6f50
    CS:  0060      EIP: c030b15a  ERR: ffffffff  EFLAGS: 00010002
 #6 [d72d3cb4] isolate_migratepages at c030b15a
 #7 [d72d3d1] zone_watermark_ok at c02d26cb
 #8 [d72d3d2c] compact_zone at c030b8de
 #9 [d72d3d68] compact_zone_order at c030bba1
torvalds#10 [d72d3db4] try_to_compact_pages at c030bc84
torvalds#11 [d72d3ddc] __alloc_pages_direct_compact at c02d61e7
torvalds#12 [d72d3e08] __alloc_pages_slowpath at c02d66c7
torvalds#13 [d72d3e78] __alloc_pages_nodemask at c02d6a97
torvalds#14 [d72d3eb8] alloc_pages_vma at c030a845
torvalds#15 [d72d3ed4] do_huge_pmd_anonymous_page at c03178eb
torvalds#16 [d72d3f00] handle_mm_fault at c02f36c6
torvalds#17 [d72d3f30] do_page_fault at c05c70ed
torvalds#18 [d72d3fb0] error_code (via page_fault) at c05c47a4
    EAX: b71ff000  EBX: 00000001  ECX: 00001600  EDX: 00000431
    DS:  007b      ESI: 08048950  ES:  007b      EDI: bfaa3788
    SS:  007b      ESP: bfaa36e0  EBP: bfaa3828  GS:  6f50
    CS:  0073      EIP: 080487c8  ERR: ffffffff  EFLAGS: 00010202

It was also reported by Herbert van den Bergh against 3.1-based kernel
with the following snippet from the console log.

BUG: unable to handle kernel paging request at 01c00008
IP: [<c0522399>] isolate_migratepages+0x119/0x390
*pdpt = 000000002f7ce001 *pde = 0000000000000000

It is expected that it also affects 3.2.x and current mainline.

The problem is that pfn_valid is only called on the first PFN being
checked and that PFN is not necessarily aligned.  Lets say we have a case
like this

H = MAX_ORDER_NR_PAGES boundary
| = pageblock boundary
m = cc->migrate_pfn
f = cc->free_pfn
o = memory hole

H------|------H------|----m-Hoooooo|ooooooH-f----|------H

The migrate_pfn is just below a memory hole and the free scanner is beyond
the hole.  When isolate_migratepages started, it scans from migrate_pfn to
migrate_pfn+pageblock_nr_pages which is now in a memory hole.  It checks
pfn_valid() on the first PFN but then scans into the hole where there are
not necessarily valid struct pages.

This patch ensures that isolate_migratepages calls pfn_valid when
necessary.

Reported-by: Herbert van den Bergh <[email protected]>
Tested-by: Herbert van den Bergh <[email protected]>
Signed-off-by: Mel Gorman <[email protected]>
Acked-by: Michal Nazarewicz <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
koenkooi pushed a commit to koenkooi/linux that referenced this pull request Mar 22, 2012
…S block during isolation for migration

commit 0bf380b upstream.

When isolating for migration, migration starts at the start of a zone
which is not necessarily pageblock aligned.  Further, it stops isolating
when COMPACT_CLUSTER_MAX pages are isolated so migrate_pfn is generally
not aligned.  This allows isolate_migratepages() to call pfn_to_page() on
an invalid PFN which can result in a crash.  This was originally reported
against a 3.0-based kernel with the following trace in a crash dump.

PID: 9902   TASK: d47aecd0  CPU: 0   COMMAND: "memcg_process_s"
 #0 [d72d3ad0] crash_kexec at c028cfdb
 #1 [d72d3b24] oops_end at c05c5322
 #2 [d72d3b38] __bad_area_nosemaphore at c0227e60
 #3 [d72d3bec] bad_area at c0227fb6
 #4 [d72d3c00] do_page_fault at c05c72ec
 #5 [d72d3c80] error_code (via page_fault) at c05c47a4
    EAX: 00000000  EBX: 000c0000  ECX: 00000001  EDX: 00000807  EBP: 000c0000
    DS:  007b      ESI: 00000001  ES:  007b      EDI: f3000a80  GS:  6f50
    CS:  0060      EIP: c030b15a  ERR: ffffffff  EFLAGS: 00010002
 #6 [d72d3cb4] isolate_migratepages at c030b15a
 #7 [d72d3d1] zone_watermark_ok at c02d26cb
 #8 [d72d3d2c] compact_zone at c030b8de
 #9 [d72d3d68] compact_zone_order at c030bba1
torvalds#10 [d72d3db4] try_to_compact_pages at c030bc84
torvalds#11 [d72d3ddc] __alloc_pages_direct_compact at c02d61e7
torvalds#12 [d72d3e08] __alloc_pages_slowpath at c02d66c7
torvalds#13 [d72d3e78] __alloc_pages_nodemask at c02d6a97
torvalds#14 [d72d3eb8] alloc_pages_vma at c030a845
torvalds#15 [d72d3ed4] do_huge_pmd_anonymous_page at c03178eb
torvalds#16 [d72d3f00] handle_mm_fault at c02f36c6
torvalds#17 [d72d3f30] do_page_fault at c05c70ed
torvalds#18 [d72d3fb0] error_code (via page_fault) at c05c47a4
    EAX: b71ff000  EBX: 00000001  ECX: 00001600  EDX: 00000431
    DS:  007b      ESI: 08048950  ES:  007b      EDI: bfaa3788
    SS:  007b      ESP: bfaa36e0  EBP: bfaa3828  GS:  6f50
    CS:  0073      EIP: 080487c8  ERR: ffffffff  EFLAGS: 00010202

It was also reported by Herbert van den Bergh against 3.1-based kernel
with the following snippet from the console log.

BUG: unable to handle kernel paging request at 01c00008
IP: [<c0522399>] isolate_migratepages+0x119/0x390
*pdpt = 000000002f7ce001 *pde = 0000000000000000

It is expected that it also affects 3.2.x and current mainline.

The problem is that pfn_valid is only called on the first PFN being
checked and that PFN is not necessarily aligned.  Lets say we have a case
like this

H = MAX_ORDER_NR_PAGES boundary
| = pageblock boundary
m = cc->migrate_pfn
f = cc->free_pfn
o = memory hole

H------|------H------|----m-Hoooooo|ooooooH-f----|------H

The migrate_pfn is just below a memory hole and the free scanner is beyond
the hole.  When isolate_migratepages started, it scans from migrate_pfn to
migrate_pfn+pageblock_nr_pages which is now in a memory hole.  It checks
pfn_valid() on the first PFN but then scans into the hole where there are
not necessarily valid struct pages.

This patch ensures that isolate_migratepages calls pfn_valid when
necessary.

Reported-by: Herbert van den Bergh <[email protected]>
Tested-by: Herbert van den Bergh <[email protected]>
Signed-off-by: Mel Gorman <[email protected]>
Acked-by: Michal Nazarewicz <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
koenkooi pushed a commit to koenkooi/linux that referenced this pull request Apr 2, 2012
…S block during isolation for migration

commit 0bf380b upstream.

When isolating for migration, migration starts at the start of a zone
which is not necessarily pageblock aligned.  Further, it stops isolating
when COMPACT_CLUSTER_MAX pages are isolated so migrate_pfn is generally
not aligned.  This allows isolate_migratepages() to call pfn_to_page() on
an invalid PFN which can result in a crash.  This was originally reported
against a 3.0-based kernel with the following trace in a crash dump.

PID: 9902   TASK: d47aecd0  CPU: 0   COMMAND: "memcg_process_s"
 #0 [d72d3ad0] crash_kexec at c028cfdb
 #1 [d72d3b24] oops_end at c05c5322
 #2 [d72d3b38] __bad_area_nosemaphore at c0227e60
 #3 [d72d3bec] bad_area at c0227fb6
 #4 [d72d3c00] do_page_fault at c05c72ec
 #5 [d72d3c80] error_code (via page_fault) at c05c47a4
    EAX: 00000000  EBX: 000c0000  ECX: 00000001  EDX: 00000807  EBP: 000c0000
    DS:  007b      ESI: 00000001  ES:  007b      EDI: f3000a80  GS:  6f50
    CS:  0060      EIP: c030b15a  ERR: ffffffff  EFLAGS: 00010002
 #6 [d72d3cb4] isolate_migratepages at c030b15a
 #7 [d72d3d1] zone_watermark_ok at c02d26cb
 #8 [d72d3d2c] compact_zone at c030b8de
 #9 [d72d3d68] compact_zone_order at c030bba1
torvalds#10 [d72d3db4] try_to_compact_pages at c030bc84
torvalds#11 [d72d3ddc] __alloc_pages_direct_compact at c02d61e7
torvalds#12 [d72d3e08] __alloc_pages_slowpath at c02d66c7
torvalds#13 [d72d3e78] __alloc_pages_nodemask at c02d6a97
torvalds#14 [d72d3eb8] alloc_pages_vma at c030a845
torvalds#15 [d72d3ed4] do_huge_pmd_anonymous_page at c03178eb
torvalds#16 [d72d3f00] handle_mm_fault at c02f36c6
torvalds#17 [d72d3f30] do_page_fault at c05c70ed
torvalds#18 [d72d3fb0] error_code (via page_fault) at c05c47a4
    EAX: b71ff000  EBX: 00000001  ECX: 00001600  EDX: 00000431
    DS:  007b      ESI: 08048950  ES:  007b      EDI: bfaa3788
    SS:  007b      ESP: bfaa36e0  EBP: bfaa3828  GS:  6f50
    CS:  0073      EIP: 080487c8  ERR: ffffffff  EFLAGS: 00010202

It was also reported by Herbert van den Bergh against 3.1-based kernel
with the following snippet from the console log.

BUG: unable to handle kernel paging request at 01c00008
IP: [<c0522399>] isolate_migratepages+0x119/0x390
*pdpt = 000000002f7ce001 *pde = 0000000000000000

It is expected that it also affects 3.2.x and current mainline.

The problem is that pfn_valid is only called on the first PFN being
checked and that PFN is not necessarily aligned.  Lets say we have a case
like this

H = MAX_ORDER_NR_PAGES boundary
| = pageblock boundary
m = cc->migrate_pfn
f = cc->free_pfn
o = memory hole

H------|------H------|----m-Hoooooo|ooooooH-f----|------H

The migrate_pfn is just below a memory hole and the free scanner is beyond
the hole.  When isolate_migratepages started, it scans from migrate_pfn to
migrate_pfn+pageblock_nr_pages which is now in a memory hole.  It checks
pfn_valid() on the first PFN but then scans into the hole where there are
not necessarily valid struct pages.

This patch ensures that isolate_migratepages calls pfn_valid when
necessary.

Reported-by: Herbert van den Bergh <[email protected]>
Tested-by: Herbert van den Bergh <[email protected]>
Signed-off-by: Mel Gorman <[email protected]>
Acked-by: Michal Nazarewicz <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
koenkooi pushed a commit to koenkooi/linux that referenced this pull request Apr 9, 2012
…S block during isolation for migration

commit 0bf380b upstream.

When isolating for migration, migration starts at the start of a zone
which is not necessarily pageblock aligned.  Further, it stops isolating
when COMPACT_CLUSTER_MAX pages are isolated so migrate_pfn is generally
not aligned.  This allows isolate_migratepages() to call pfn_to_page() on
an invalid PFN which can result in a crash.  This was originally reported
against a 3.0-based kernel with the following trace in a crash dump.

PID: 9902   TASK: d47aecd0  CPU: 0   COMMAND: "memcg_process_s"
 #0 [d72d3ad0] crash_kexec at c028cfdb
 #1 [d72d3b24] oops_end at c05c5322
 #2 [d72d3b38] __bad_area_nosemaphore at c0227e60
 #3 [d72d3bec] bad_area at c0227fb6
 #4 [d72d3c00] do_page_fault at c05c72ec
 #5 [d72d3c80] error_code (via page_fault) at c05c47a4
    EAX: 00000000  EBX: 000c0000  ECX: 00000001  EDX: 00000807  EBP: 000c0000
    DS:  007b      ESI: 00000001  ES:  007b      EDI: f3000a80  GS:  6f50
    CS:  0060      EIP: c030b15a  ERR: ffffffff  EFLAGS: 00010002
 #6 [d72d3cb4] isolate_migratepages at c030b15a
 #7 [d72d3d1] zone_watermark_ok at c02d26cb
 #8 [d72d3d2c] compact_zone at c030b8de
 #9 [d72d3d68] compact_zone_order at c030bba1
torvalds#10 [d72d3db4] try_to_compact_pages at c030bc84
torvalds#11 [d72d3ddc] __alloc_pages_direct_compact at c02d61e7
torvalds#12 [d72d3e08] __alloc_pages_slowpath at c02d66c7
torvalds#13 [d72d3e78] __alloc_pages_nodemask at c02d6a97
torvalds#14 [d72d3eb8] alloc_pages_vma at c030a845
torvalds#15 [d72d3ed4] do_huge_pmd_anonymous_page at c03178eb
torvalds#16 [d72d3f00] handle_mm_fault at c02f36c6
torvalds#17 [d72d3f30] do_page_fault at c05c70ed
torvalds#18 [d72d3fb0] error_code (via page_fault) at c05c47a4
    EAX: b71ff000  EBX: 00000001  ECX: 00001600  EDX: 00000431
    DS:  007b      ESI: 08048950  ES:  007b      EDI: bfaa3788
    SS:  007b      ESP: bfaa36e0  EBP: bfaa3828  GS:  6f50
    CS:  0073      EIP: 080487c8  ERR: ffffffff  EFLAGS: 00010202

It was also reported by Herbert van den Bergh against 3.1-based kernel
with the following snippet from the console log.

BUG: unable to handle kernel paging request at 01c00008
IP: [<c0522399>] isolate_migratepages+0x119/0x390
*pdpt = 000000002f7ce001 *pde = 0000000000000000

It is expected that it also affects 3.2.x and current mainline.

The problem is that pfn_valid is only called on the first PFN being
checked and that PFN is not necessarily aligned.  Lets say we have a case
like this

H = MAX_ORDER_NR_PAGES boundary
| = pageblock boundary
m = cc->migrate_pfn
f = cc->free_pfn
o = memory hole

H------|------H------|----m-Hoooooo|ooooooH-f----|------H

The migrate_pfn is just below a memory hole and the free scanner is beyond
the hole.  When isolate_migratepages started, it scans from migrate_pfn to
migrate_pfn+pageblock_nr_pages which is now in a memory hole.  It checks
pfn_valid() on the first PFN but then scans into the hole where there are
not necessarily valid struct pages.

This patch ensures that isolate_migratepages calls pfn_valid when
necessary.

Reported-by: Herbert van den Bergh <[email protected]>
Tested-by: Herbert van den Bergh <[email protected]>
Signed-off-by: Mel Gorman <[email protected]>
Acked-by: Michal Nazarewicz <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
koenkooi pushed a commit to koenkooi/linux that referenced this pull request Apr 11, 2012
…S block during isolation for migration

commit 0bf380b upstream.

When isolating for migration, migration starts at the start of a zone
which is not necessarily pageblock aligned.  Further, it stops isolating
when COMPACT_CLUSTER_MAX pages are isolated so migrate_pfn is generally
not aligned.  This allows isolate_migratepages() to call pfn_to_page() on
an invalid PFN which can result in a crash.  This was originally reported
against a 3.0-based kernel with the following trace in a crash dump.

PID: 9902   TASK: d47aecd0  CPU: 0   COMMAND: "memcg_process_s"
 #0 [d72d3ad0] crash_kexec at c028cfdb
 #1 [d72d3b24] oops_end at c05c5322
 #2 [d72d3b38] __bad_area_nosemaphore at c0227e60
 #3 [d72d3bec] bad_area at c0227fb6
 #4 [d72d3c00] do_page_fault at c05c72ec
 #5 [d72d3c80] error_code (via page_fault) at c05c47a4
    EAX: 00000000  EBX: 000c0000  ECX: 00000001  EDX: 00000807  EBP: 000c0000
    DS:  007b      ESI: 00000001  ES:  007b      EDI: f3000a80  GS:  6f50
    CS:  0060      EIP: c030b15a  ERR: ffffffff  EFLAGS: 00010002
 #6 [d72d3cb4] isolate_migratepages at c030b15a
 #7 [d72d3d1] zone_watermark_ok at c02d26cb
 #8 [d72d3d2c] compact_zone at c030b8de
 #9 [d72d3d68] compact_zone_order at c030bba1
torvalds#10 [d72d3db4] try_to_compact_pages at c030bc84
torvalds#11 [d72d3ddc] __alloc_pages_direct_compact at c02d61e7
torvalds#12 [d72d3e08] __alloc_pages_slowpath at c02d66c7
torvalds#13 [d72d3e78] __alloc_pages_nodemask at c02d6a97
torvalds#14 [d72d3eb8] alloc_pages_vma at c030a845
torvalds#15 [d72d3ed4] do_huge_pmd_anonymous_page at c03178eb
torvalds#16 [d72d3f00] handle_mm_fault at c02f36c6
torvalds#17 [d72d3f30] do_page_fault at c05c70ed
torvalds#18 [d72d3fb0] error_code (via page_fault) at c05c47a4
    EAX: b71ff000  EBX: 00000001  ECX: 00001600  EDX: 00000431
    DS:  007b      ESI: 08048950  ES:  007b      EDI: bfaa3788
    SS:  007b      ESP: bfaa36e0  EBP: bfaa3828  GS:  6f50
    CS:  0073      EIP: 080487c8  ERR: ffffffff  EFLAGS: 00010202

It was also reported by Herbert van den Bergh against 3.1-based kernel
with the following snippet from the console log.

BUG: unable to handle kernel paging request at 01c00008
IP: [<c0522399>] isolate_migratepages+0x119/0x390
*pdpt = 000000002f7ce001 *pde = 0000000000000000

It is expected that it also affects 3.2.x and current mainline.

The problem is that pfn_valid is only called on the first PFN being
checked and that PFN is not necessarily aligned.  Lets say we have a case
like this

H = MAX_ORDER_NR_PAGES boundary
| = pageblock boundary
m = cc->migrate_pfn
f = cc->free_pfn
o = memory hole

H------|------H------|----m-Hoooooo|ooooooH-f----|------H

The migrate_pfn is just below a memory hole and the free scanner is beyond
the hole.  When isolate_migratepages started, it scans from migrate_pfn to
migrate_pfn+pageblock_nr_pages which is now in a memory hole.  It checks
pfn_valid() on the first PFN but then scans into the hole where there are
not necessarily valid struct pages.

This patch ensures that isolate_migratepages calls pfn_valid when
necessary.

Reported-by: Herbert van den Bergh <[email protected]>
Tested-by: Herbert van den Bergh <[email protected]>
Signed-off-by: Mel Gorman <[email protected]>
Acked-by: Michal Nazarewicz <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
koenkooi pushed a commit to koenkooi/linux that referenced this pull request Apr 12, 2012
…S block during isolation for migration

commit 0bf380b upstream.

When isolating for migration, migration starts at the start of a zone
which is not necessarily pageblock aligned.  Further, it stops isolating
when COMPACT_CLUSTER_MAX pages are isolated so migrate_pfn is generally
not aligned.  This allows isolate_migratepages() to call pfn_to_page() on
an invalid PFN which can result in a crash.  This was originally reported
against a 3.0-based kernel with the following trace in a crash dump.

PID: 9902   TASK: d47aecd0  CPU: 0   COMMAND: "memcg_process_s"
 #0 [d72d3ad0] crash_kexec at c028cfdb
 #1 [d72d3b24] oops_end at c05c5322
 #2 [d72d3b38] __bad_area_nosemaphore at c0227e60
 #3 [d72d3bec] bad_area at c0227fb6
 #4 [d72d3c00] do_page_fault at c05c72ec
 #5 [d72d3c80] error_code (via page_fault) at c05c47a4
    EAX: 00000000  EBX: 000c0000  ECX: 00000001  EDX: 00000807  EBP: 000c0000
    DS:  007b      ESI: 00000001  ES:  007b      EDI: f3000a80  GS:  6f50
    CS:  0060      EIP: c030b15a  ERR: ffffffff  EFLAGS: 00010002
 #6 [d72d3cb4] isolate_migratepages at c030b15a
 #7 [d72d3d1] zone_watermark_ok at c02d26cb
 #8 [d72d3d2c] compact_zone at c030b8de
 #9 [d72d3d68] compact_zone_order at c030bba1
torvalds#10 [d72d3db4] try_to_compact_pages at c030bc84
torvalds#11 [d72d3ddc] __alloc_pages_direct_compact at c02d61e7
torvalds#12 [d72d3e08] __alloc_pages_slowpath at c02d66c7
torvalds#13 [d72d3e78] __alloc_pages_nodemask at c02d6a97
torvalds#14 [d72d3eb8] alloc_pages_vma at c030a845
torvalds#15 [d72d3ed4] do_huge_pmd_anonymous_page at c03178eb
torvalds#16 [d72d3f00] handle_mm_fault at c02f36c6
torvalds#17 [d72d3f30] do_page_fault at c05c70ed
torvalds#18 [d72d3fb0] error_code (via page_fault) at c05c47a4
    EAX: b71ff000  EBX: 00000001  ECX: 00001600  EDX: 00000431
    DS:  007b      ESI: 08048950  ES:  007b      EDI: bfaa3788
    SS:  007b      ESP: bfaa36e0  EBP: bfaa3828  GS:  6f50
    CS:  0073      EIP: 080487c8  ERR: ffffffff  EFLAGS: 00010202

It was also reported by Herbert van den Bergh against 3.1-based kernel
with the following snippet from the console log.

BUG: unable to handle kernel paging request at 01c00008
IP: [<c0522399>] isolate_migratepages+0x119/0x390
*pdpt = 000000002f7ce001 *pde = 0000000000000000

It is expected that it also affects 3.2.x and current mainline.

The problem is that pfn_valid is only called on the first PFN being
checked and that PFN is not necessarily aligned.  Lets say we have a case
like this

H = MAX_ORDER_NR_PAGES boundary
| = pageblock boundary
m = cc->migrate_pfn
f = cc->free_pfn
o = memory hole

H------|------H------|----m-Hoooooo|ooooooH-f----|------H

The migrate_pfn is just below a memory hole and the free scanner is beyond
the hole.  When isolate_migratepages started, it scans from migrate_pfn to
migrate_pfn+pageblock_nr_pages which is now in a memory hole.  It checks
pfn_valid() on the first PFN but then scans into the hole where there are
not necessarily valid struct pages.

This patch ensures that isolate_migratepages calls pfn_valid when
necessary.

Reported-by: Herbert van den Bergh <[email protected]>
Tested-by: Herbert van den Bergh <[email protected]>
Signed-off-by: Mel Gorman <[email protected]>
Acked-by: Michal Nazarewicz <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
psanford pushed a commit to retailnext/linux that referenced this pull request Apr 16, 2012
BugLink: http://bugs.launchpad.net/bugs/907778

commit ea51d13 upstream.

If the pte mapping in generic_perform_write() is unmapped between
iov_iter_fault_in_readable() and iov_iter_copy_from_user_atomic(), the
"copied" parameter to ->end_write can be zero. ext4 couldn't cope with
it with delayed allocations enabled. This skips the i_disksize
enlargement logic if copied is zero and no new data was appeneded to
the inode.

 gdb> bt
 #0  0xffffffff811afe80 in ext4_da_should_update_i_disksize (file=0xffff88003f606a80, mapping=0xffff88001d3824e0, pos=0x1\
 08000, len=0x1000, copied=0x0, page=0xffffea0000d792e8, fsdata=0x0) at fs/ext4/inode.c:2467
 #1  ext4_da_write_end (file=0xffff88003f606a80, mapping=0xffff88001d3824e0, pos=0x108000, len=0x1000, copied=0x0, page=0\
 xffffea0000d792e8, fsdata=0x0) at fs/ext4/inode.c:2512
 #2  0xffffffff810d97f1 in generic_perform_write (iocb=<value optimized out>, iov=<value optimized out>, nr_segs=<value o\
 ptimized out>, pos=0x108000, ppos=0xffff88001e26be40, count=<value optimized out>, written=0x0) at mm/filemap.c:2440
 #3  generic_file_buffered_write (iocb=<value optimized out>, iov=<value optimized out>, nr_segs=<value optimized out>, p\
 os=0x108000, ppos=0xffff88001e26be40, count=<value optimized out>, written=0x0) at mm/filemap.c:2482
 #4  0xffffffff810db5d1 in __generic_file_aio_write (iocb=0xffff88001e26bde8, iov=0xffff88001e26bec8, nr_segs=0x1, ppos=0\
 xffff88001e26be40) at mm/filemap.c:2600
 #5  0xffffffff810db853 in generic_file_aio_write (iocb=0xffff88001e26bde8, iov=0xffff88001e26bec8, nr_segs=<value optimi\
 zed out>, pos=<value optimized out>) at mm/filemap.c:2632
 torvalds#6  0xffffffff811a71aa in ext4_file_write (iocb=0xffff88001e26bde8, iov=0xffff88001e26bec8, nr_segs=0x1, pos=0x108000) a\
 t fs/ext4/file.c:136
 torvalds#7  0xffffffff811375aa in do_sync_write (filp=0xffff88003f606a80, buf=<value optimized out>, len=<value optimized out>, \
 ppos=0xffff88001e26bf48) at fs/read_write.c:406
 torvalds#8  0xffffffff81137e56 in vfs_write (file=0xffff88003f606a80, buf=0x1ec2960 <Address 0x1ec2960 out of bounds>, count=0x4\
 000, pos=0xffff88001e26bf48) at fs/read_write.c:435
 torvalds#9  0xffffffff8113816c in sys_write (fd=<value optimized out>, buf=0x1ec2960 <Address 0x1ec2960 out of bounds>, count=0x\
 4000) at fs/read_write.c:487
 torvalds#10 <signal handler called>
 torvalds#11 0x00007f120077a390 in __brk_reservation_fn_dmi_alloc__ ()
 torvalds#12 0x0000000000000000 in ?? ()
 gdb> print offset
 $22 = 0xffffffffffffffff
 gdb> print idx
 $23 = 0xffffffff
 gdb> print inode->i_blkbits
 $24 = 0xc
 gdb> up
 #1  ext4_da_write_end (file=0xffff88003f606a80, mapping=0xffff88001d3824e0, pos=0x108000, len=0x1000, copied=0x0, page=0\
 xffffea0000d792e8, fsdata=0x0) at fs/ext4/inode.c:2512
 2512                    if (ext4_da_should_update_i_disksize(page, end)) {
 gdb> print start
 $25 = 0x0
 gdb> print end
 $26 = 0xffffffffffffffff
 gdb> print pos
 $27 = 0x108000
 gdb> print new_i_size
 $28 = 0x108000
 gdb> print ((struct ext4_inode_info *)((char *)inode-((int)(&((struct ext4_inode_info *)0)->vfs_inode))))->i_disksize
 $29 = 0xd9000
 gdb> down
 2467            for (i = 0; i < idx; i++)
 gdb> print i
 $30 = 0xd44acbee

This is 100% reproducible with some autonuma development code tuned in
a very aggressive manner (not normal way even for knumad) which does
"exotic" changes to the ptes. It wouldn't normally trigger but I don't
see why it can't happen normally if the page is added to swap cache in
between the two faults leading to "copied" being zero (which then
hangs in ext4). So it should be fixed. Especially possible with lumpy
reclaim (albeit disabled if compaction is enabled) as that would
ignore the young bits in the ptes.

Signed-off-by: Andrea Arcangeli <[email protected]>
Signed-off-by: "Theodore Ts'o" <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
Signed-off-by: Tim Gardner <[email protected]>
Signed-off-by: Brad Figg <[email protected]>
roxell added a commit to roxell/linux that referenced this pull request Nov 1, 2024
[  123.491737][    T1] Unexpected kernel BRK exception at EL1
[  123.497593][    T1] Internal error: ptrace BRK handler: f20003e8 [#1] PREEMPT SMP
[  123.500785][    T1] Modules linked in:
[  123.502567][    T1] CPU: 0 PID: 1 Comm: swapper/0 Tainted: G        W         5.8.0-rc3-next-20200630-00003-g15e24419c239-dirty torvalds#11
[  123.507468][    T1] Hardware name: linux,dummy-virt (DT)
[  123.509826][    T1] pstate: 80400005 (Nzcv daif +PAN -UAO BTYPE=--)
[  123.512609][    T1] pc : of_unittest_untrack_overlay+0x64/0x134
[  123.515245][    T1] lr : of_unittest_untrack_overlay+0x64/0x134
[  123.517848][    T1] sp : ffff00006a65fb30
[  123.519668][    T1] x29: ffff00006a65fb30 x28: 0000000000000000
[  123.522295][    T1] x27: ffff00006a65fc30 x26: ffffa00016b86f00
[  123.524937][    T1] x25: 0000000000000000 x24: 0000000000000000
[  123.527592][    T1] x23: ffffa00014c72540 x22: ffffa00016b86000
[  123.530191][    T1] x21: 0000000000000000 x20: 00000000ffffffff
[  123.532845][    T1] x19: 00000000ffffffff x18: 0000000000002690
[  123.535547][    T1] x17: 0000000000002718 x16: 00000000000014b8
[  123.538299][    T1] x15: 0000000000000001 x14: 0080000000000000
[  123.541055][    T1] x13: 0000000000000002 x12: ffff94000298d209
[  123.543801][    T1] x11: 1ffff4000298d208 x10: ffff94000298d208
[  123.546580][    T1] x9 : dfffa00000000000 x8 : ffffa00014c69047
[  123.549247][    T1] x7 : 0000000000000001 x6 : ffffa00014c69040
[  123.552026][    T1] x5 : ffff00006a654040 x4 : 0000000000000000
[  123.554799][    T1] x3 : ffffa00011d59d04 x2 : 00000000ffffffff
[  123.557541][    T1] x1 : ffff00006a654040 x0 : 0000000000000000
[  123.560390][    T1] Call trace:
[  123.561935][    T1]  of_unittest_untrack_overlay+0x64/0x134
[  123.564469][    T1]  of_unittest+0x2220/0x2438
[  123.566585][    T1]  do_one_initcall+0x470/0xa10
[  123.568751][    T1]  kernel_init_freeable+0x510/0x5f0
[  123.571123][    T1]  kernel_init+0x18/0x1e8
[  123.573078][    T1]  ret_from_fork+0x10/0x18
[  123.575119][    T1] Code: 97978a9c d4210000 14000024 97978a99 (d4207d00)
[  123.578138][    T1] ---[ end trace c4e049fb5e3b0ba0 ]---
[  123.580449][    T1] Kernel panic - not syncing: Fatal exception
[  123.583116][    T1] Kernel Offset: disabled
[  123.585066][    T1] CPU features: 0x240002,20002004
[  123.587259][    T1] Memory Limit: none
[  123.588986][    T1] ---[ end Kernel panic - not syncing: Fatal exception ]---

Signed-off-by: Anders Roxell <[email protected]>
lougovsk pushed a commit to lougovsk/linux that referenced this pull request Nov 1, 2024
Disable strict aliasing, as has been done in the kernel proper for decades
(literally since before git history) to fix issues where gcc will optimize
away loads in code that looks 100% correct, but is _technically_ undefined
behavior, and thus can be thrown away by the compiler.

E.g. arm64's vPMU counter access test casts a uint64_t (unsigned long)
pointer to a u64 (unsigned long long) pointer when setting PMCR.N via
u64p_replace_bits(), which gcc-13 detects and optimizes away, i.e. ignores
the result and uses the original PMCR.

The issue is most easily observed by making set_pmcr_n() noinline and
wrapping the call with printf(), e.g. sans comments, for this code:

  printf("orig = %lx, next = %lx, want = %lu\n", pmcr_orig, pmcr, pmcr_n);
  set_pmcr_n(&pmcr, pmcr_n);
  printf("orig = %lx, next = %lx, want = %lu\n", pmcr_orig, pmcr, pmcr_n);

gcc-13 generates:

 0000000000401c90 <set_pmcr_n>:
  401c90:       f9400002        ldr     x2, [x0]
  401c94:       b3751022        bfi     x2, x1, torvalds#11, #5
  401c98:       f9000002        str     x2, [x0]
  401c9c:       d65f03c0        ret

 0000000000402660 <test_create_vpmu_vm_with_pmcr_n>:
  402724:       aa1403e3        mov     x3, x20
  402728:       aa1503e2        mov     x2, x21
  40272c:       aa1603e0        mov     x0, x22
  402730:       aa1503e1        mov     x1, x21
  402734:       940060ff        bl      41ab30 <_IO_printf>
  402738:       aa1403e1        mov     x1, x20
  40273c:       910183e0        add     x0, sp, #0x60
  402740:       97fffd54        bl      401c90 <set_pmcr_n>
  402744:       aa1403e3        mov     x3, x20
  402748:       aa1503e2        mov     x2, x21
  40274c:       aa1503e1        mov     x1, x21
  402750:       aa1603e0        mov     x0, x22
  402754:       940060f7        bl      41ab30 <_IO_printf>

with the value stored in [sp + 0x60] ignored by both printf() above and
in the test proper, resulting in a false failure due to vcpu_set_reg()
simply storing the original value, not the intended value.

  $ ./vpmu_counter_access
  Random seed: 0x6b8b4567
  orig = 3040, next = 3040, want = 0
  orig = 3040, next = 3040, want = 0
  ==== Test Assertion Failure ====
    aarch64/vpmu_counter_access.c:505: pmcr_n == get_pmcr_n(pmcr)
    pid=71578 tid=71578 errno=9 - Bad file descriptor
       1        0x400673: run_access_test at vpmu_counter_access.c:522
       2         (inlined by) main at vpmu_counter_access.c:643
       3        0x4132d7: __libc_start_call_main at libc-start.o:0
       4        0x413653: __libc_start_main at ??:0
       5        0x40106f: _start at ??:0
    Failed to update PMCR.N to 0 (received: 6)

Somewhat bizarrely, gcc-11 also exhibits the same behavior, but only if
set_pmcr_n() is marked noinline, whereas gcc-13 fails even if set_pmcr_n()
is inlined in its sole caller.

Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=116912
Signed-off-by: Sean Christopherson <[email protected]>
Message-Id: <[email protected]>
lougovsk pushed a commit to lougovsk/linux that referenced this pull request Nov 1, 2024
Disable strict aliasing, as has been done in the kernel proper for decades
(literally since before git history) to fix issues where gcc will optimize
away loads in code that looks 100% correct, but is _technically_ undefined
behavior, and thus can be thrown away by the compiler.

E.g. arm64's vPMU counter access test casts a uint64_t (unsigned long)
pointer to a u64 (unsigned long long) pointer when setting PMCR.N via
u64p_replace_bits(), which gcc-13 detects and optimizes away, i.e. ignores
the result and uses the original PMCR.

The issue is most easily observed by making set_pmcr_n() noinline and
wrapping the call with printf(), e.g. sans comments, for this code:

  printf("orig = %lx, next = %lx, want = %lu\n", pmcr_orig, pmcr, pmcr_n);
  set_pmcr_n(&pmcr, pmcr_n);
  printf("orig = %lx, next = %lx, want = %lu\n", pmcr_orig, pmcr, pmcr_n);

gcc-13 generates:

 0000000000401c90 <set_pmcr_n>:
  401c90:       f9400002        ldr     x2, [x0]
  401c94:       b3751022        bfi     x2, x1, torvalds#11, #5
  401c98:       f9000002        str     x2, [x0]
  401c9c:       d65f03c0        ret

 0000000000402660 <test_create_vpmu_vm_with_pmcr_n>:
  402724:       aa1403e3        mov     x3, x20
  402728:       aa1503e2        mov     x2, x21
  40272c:       aa1603e0        mov     x0, x22
  402730:       aa1503e1        mov     x1, x21
  402734:       940060ff        bl      41ab30 <_IO_printf>
  402738:       aa1403e1        mov     x1, x20
  40273c:       910183e0        add     x0, sp, #0x60
  402740:       97fffd54        bl      401c90 <set_pmcr_n>
  402744:       aa1403e3        mov     x3, x20
  402748:       aa1503e2        mov     x2, x21
  40274c:       aa1503e1        mov     x1, x21
  402750:       aa1603e0        mov     x0, x22
  402754:       940060f7        bl      41ab30 <_IO_printf>

with the value stored in [sp + 0x60] ignored by both printf() above and
in the test proper, resulting in a false failure due to vcpu_set_reg()
simply storing the original value, not the intended value.

  $ ./vpmu_counter_access
  Random seed: 0x6b8b4567
  orig = 3040, next = 3040, want = 0
  orig = 3040, next = 3040, want = 0
  ==== Test Assertion Failure ====
    aarch64/vpmu_counter_access.c:505: pmcr_n == get_pmcr_n(pmcr)
    pid=71578 tid=71578 errno=9 - Bad file descriptor
       1        0x400673: run_access_test at vpmu_counter_access.c:522
       2         (inlined by) main at vpmu_counter_access.c:643
       3        0x4132d7: __libc_start_call_main at libc-start.o:0
       4        0x413653: __libc_start_main at ??:0
       5        0x40106f: _start at ??:0
    Failed to update PMCR.N to 0 (received: 6)

Somewhat bizarrely, gcc-11 also exhibits the same behavior, but only if
set_pmcr_n() is marked noinline, whereas gcc-13 fails even if set_pmcr_n()
is inlined in its sole caller.

Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=116912
Signed-off-by: Sean Christopherson <[email protected]>
Message-Id: <[email protected]>
lougovsk pushed a commit to lougovsk/linux that referenced this pull request Nov 1, 2024
Disable strict aliasing, as has been done in the kernel proper for decades
(literally since before git history) to fix issues where gcc will optimize
away loads in code that looks 100% correct, but is _technically_ undefined
behavior, and thus can be thrown away by the compiler.

E.g. arm64's vPMU counter access test casts a uint64_t (unsigned long)
pointer to a u64 (unsigned long long) pointer when setting PMCR.N via
u64p_replace_bits(), which gcc-13 detects and optimizes away, i.e. ignores
the result and uses the original PMCR.

The issue is most easily observed by making set_pmcr_n() noinline and
wrapping the call with printf(), e.g. sans comments, for this code:

  printf("orig = %lx, next = %lx, want = %lu\n", pmcr_orig, pmcr, pmcr_n);
  set_pmcr_n(&pmcr, pmcr_n);
  printf("orig = %lx, next = %lx, want = %lu\n", pmcr_orig, pmcr, pmcr_n);

gcc-13 generates:

 0000000000401c90 <set_pmcr_n>:
  401c90:       f9400002        ldr     x2, [x0]
  401c94:       b3751022        bfi     x2, x1, torvalds#11, #5
  401c98:       f9000002        str     x2, [x0]
  401c9c:       d65f03c0        ret

 0000000000402660 <test_create_vpmu_vm_with_pmcr_n>:
  402724:       aa1403e3        mov     x3, x20
  402728:       aa1503e2        mov     x2, x21
  40272c:       aa1603e0        mov     x0, x22
  402730:       aa1503e1        mov     x1, x21
  402734:       940060ff        bl      41ab30 <_IO_printf>
  402738:       aa1403e1        mov     x1, x20
  40273c:       910183e0        add     x0, sp, #0x60
  402740:       97fffd54        bl      401c90 <set_pmcr_n>
  402744:       aa1403e3        mov     x3, x20
  402748:       aa1503e2        mov     x2, x21
  40274c:       aa1503e1        mov     x1, x21
  402750:       aa1603e0        mov     x0, x22
  402754:       940060f7        bl      41ab30 <_IO_printf>

with the value stored in [sp + 0x60] ignored by both printf() above and
in the test proper, resulting in a false failure due to vcpu_set_reg()
simply storing the original value, not the intended value.

  $ ./vpmu_counter_access
  Random seed: 0x6b8b4567
  orig = 3040, next = 3040, want = 0
  orig = 3040, next = 3040, want = 0
  ==== Test Assertion Failure ====
    aarch64/vpmu_counter_access.c:505: pmcr_n == get_pmcr_n(pmcr)
    pid=71578 tid=71578 errno=9 - Bad file descriptor
       1        0x400673: run_access_test at vpmu_counter_access.c:522
       2         (inlined by) main at vpmu_counter_access.c:643
       3        0x4132d7: __libc_start_call_main at libc-start.o:0
       4        0x413653: __libc_start_main at ??:0
       5        0x40106f: _start at ??:0
    Failed to update PMCR.N to 0 (received: 6)

Somewhat bizarrely, gcc-11 also exhibits the same behavior, but only if
set_pmcr_n() is marked noinline, whereas gcc-13 fails even if set_pmcr_n()
is inlined in its sole caller.

Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=116912
Signed-off-by: Sean Christopherson <[email protected]>
Message-Id: <[email protected]>
sean-jc added a commit to sean-jc/linux that referenced this pull request Nov 5, 2024
Disable strict aliasing, as has been done in the kernel proper for decades
(literally since before git history) to fix issues where gcc will optimize
away loads in code that looks 100% correct, but is _technically_ undefined
behavior, and thus can be thrown away by the compiler.

E.g. arm64's vPMU counter access test casts a uint64_t (unsigned long)
pointer to a u64 (unsigned long long) pointer when setting PMCR.N via
u64p_replace_bits(), which gcc-13 detects and optimizes away, i.e. ignores
the result and uses the original PMCR.

The issue is most easily observed by making set_pmcr_n() noinline and
wrapping the call with printf(), e.g. sans comments, for this code:

  printf("orig = %lx, next = %lx, want = %lu\n", pmcr_orig, pmcr, pmcr_n);
  set_pmcr_n(&pmcr, pmcr_n);
  printf("orig = %lx, next = %lx, want = %lu\n", pmcr_orig, pmcr, pmcr_n);

gcc-13 generates:

 0000000000401c90 <set_pmcr_n>:
  401c90:       f9400002        ldr     x2, [x0]
  401c94:       b3751022        bfi     x2, x1, torvalds#11, #5
  401c98:       f9000002        str     x2, [x0]
  401c9c:       d65f03c0        ret

 0000000000402660 <test_create_vpmu_vm_with_pmcr_n>:
  402724:       aa1403e3        mov     x3, x20
  402728:       aa1503e2        mov     x2, x21
  40272c:       aa1603e0        mov     x0, x22
  402730:       aa1503e1        mov     x1, x21
  402734:       940060ff        bl      41ab30 <_IO_printf>
  402738:       aa1403e1        mov     x1, x20
  40273c:       910183e0        add     x0, sp, #0x60
  402740:       97fffd54        bl      401c90 <set_pmcr_n>
  402744:       aa1403e3        mov     x3, x20
  402748:       aa1503e2        mov     x2, x21
  40274c:       aa1503e1        mov     x1, x21
  402750:       aa1603e0        mov     x0, x22
  402754:       940060f7        bl      41ab30 <_IO_printf>

with the value stored in [sp + 0x60] ignored by both printf() above and
in the test proper, resulting in a false failure due to vcpu_set_reg()
simply storing the original value, not the intended value.

  $ ./vpmu_counter_access
  Random seed: 0x6b8b4567
  orig = 3040, next = 3040, want = 0
  orig = 3040, next = 3040, want = 0
  ==== Test Assertion Failure ====
    aarch64/vpmu_counter_access.c:505: pmcr_n == get_pmcr_n(pmcr)
    pid=71578 tid=71578 errno=9 - Bad file descriptor
       1        0x400673: run_access_test at vpmu_counter_access.c:522
       2         (inlined by) main at vpmu_counter_access.c:643
       3        0x4132d7: __libc_start_call_main at libc-start.o:0
       4        0x413653: __libc_start_main at ??:0
       5        0x40106f: _start at ??:0
    Failed to update PMCR.N to 0 (received: 6)

Somewhat bizarrely, gcc-11 also exhibits the same behavior, but only if
set_pmcr_n() is marked noinline, whereas gcc-13 fails even if set_pmcr_n()
is inlined in its sole caller.

Cc: [email protected]
Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=116912
Signed-off-by: Sean Christopherson <[email protected]>
MingcongBai pushed a commit to AOSC-Tracking/linux that referenced this pull request Nov 6, 2024
commit e972b08 upstream.

We're seeing crashes from rq_qos_wake_function that look like this:

  BUG: unable to handle page fault for address: ffffafe180a40084
  #PF: supervisor write access in kernel mode
  #PF: error_code(0x0002) - not-present page
  PGD 100000067 P4D 100000067 PUD 10027c067 PMD 10115d067 PTE 0
  Oops: Oops: 0002 [#1] PREEMPT SMP PTI
  CPU: 17 UID: 0 PID: 0 Comm: swapper/17 Not tainted 6.12.0-rc3-00013-geca631b8fe80 torvalds#11
  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.0-0-gd239552ce722-prebuilt.qemu.org 04/01/2014
  RIP: 0010:_raw_spin_lock_irqsave+0x1d/0x40
  Code: 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 0f 1f 44 00 00 41 54 9c 41 5c fa 65 ff 05 62 97 30 4c 31 c0 ba 01 00 00 00 <f0> 0f b1 17 75 0a 4c 89 e0 41 5c c3 cc cc cc cc 89 c6 e8 2c 0b 00
  RSP: 0018:ffffafe180580ca0 EFLAGS: 00010046
  RAX: 0000000000000000 RBX: ffffafe180a3f7a8 RCX: 0000000000000011
  RDX: 0000000000000001 RSI: 0000000000000003 RDI: ffffafe180a40084
  RBP: 0000000000000000 R08: 00000000001e7240 R09: 0000000000000011
  R10: 0000000000000028 R11: 0000000000000888 R12: 0000000000000002
  R13: ffffafe180a40084 R14: 0000000000000000 R15: 0000000000000003
  FS:  0000000000000000(0000) GS:ffff9aaf1f280000(0000) knlGS:0000000000000000
  CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
  CR2: ffffafe180a40084 CR3: 000000010e428002 CR4: 0000000000770ef0
  DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
  DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
  PKRU: 55555554
  Call Trace:
   <IRQ>
   try_to_wake_up+0x5a/0x6a0
   rq_qos_wake_function+0x71/0x80
   __wake_up_common+0x75/0xa0
   __wake_up+0x36/0x60
   scale_up.part.0+0x50/0x110
   wb_timer_fn+0x227/0x450
   ...

So rq_qos_wake_function() calls wake_up_process(data->task), which calls
try_to_wake_up(), which faults in raw_spin_lock_irqsave(&p->pi_lock).

p comes from data->task, and data comes from the waitqueue entry, which
is stored on the waiter's stack in rq_qos_wait(). Analyzing the core
dump with drgn, I found that the waiter had already woken up and moved
on to a completely unrelated code path, clobbering what was previously
data->task. Meanwhile, the waker was passing the clobbered garbage in
data->task to wake_up_process(), leading to the crash.

What's happening is that in between rq_qos_wake_function() deleting the
waitqueue entry and calling wake_up_process(), rq_qos_wait() is finding
that it already got a token and returning. The race looks like this:

rq_qos_wait()                           rq_qos_wake_function()
==============================================================
prepare_to_wait_exclusive()
                                        data->got_token = true;
                                        list_del_init(&curr->entry);
if (data.got_token)
        break;
finish_wait(&rqw->wait, &data.wq);
  ^- returns immediately because
     list_empty_careful(&wq_entry->entry)
     is true
... return, go do something else ...
                                        wake_up_process(data->task)
                                          (NO LONGER VALID!)-^

Normally, finish_wait() is supposed to synchronize against the waker.
But, as noted above, it is returning immediately because the waitqueue
entry has already been removed from the waitqueue.

The bug is that rq_qos_wake_function() is accessing the waitqueue entry
AFTER deleting it. Note that autoremove_wake_function() wakes the waiter
and THEN deletes the waitqueue entry, which is the proper order.

Fix it by swapping the order. We also need to use
list_del_init_careful() to match the list_empty_careful() in
finish_wait().

Fixes: 38cfb5a ("blk-wbt: improve waking of tasks")
Cc: [email protected]
Signed-off-by: Omar Sandoval <[email protected]>
Acked-by: Tejun Heo <[email protected]>
Reviewed-by: Johannes Thumshirn <[email protected]>
Link: https://lore.kernel.org/r/d3bee2463a67b1ee597211823bf7ad3721c26e41.1729014591.git.osandov@fb.com
Signed-off-by: Jens Axboe <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
(cherry picked from commit 4c5b123)
mj22226 pushed a commit to mj22226/linux that referenced this pull request Nov 6, 2024
[ Upstream commit 3deb12c ]

Enabling CONFIG_PROVE_RCU_LIST with its dependence CONFIG_RCU_EXPERT
creates this splat when an MPTCP socket is created:

  =============================
  WARNING: suspicious RCU usage
  6.12.0-rc2+ torvalds#11 Not tainted
  -----------------------------
  net/mptcp/sched.c:44 RCU-list traversed in non-reader section!!

  other info that might help us debug this:

  rcu_scheduler_active = 2, debug_locks = 1
  no locks held by mptcp_connect/176.

  stack backtrace:
  CPU: 0 UID: 0 PID: 176 Comm: mptcp_connect Not tainted 6.12.0-rc2+ torvalds#11
  Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
  Call Trace:
   <TASK>
   dump_stack_lvl (lib/dump_stack.c:123)
   lockdep_rcu_suspicious (kernel/locking/lockdep.c:6822)
   mptcp_sched_find (net/mptcp/sched.c:44 (discriminator 7))
   mptcp_init_sock (net/mptcp/protocol.c:2867 (discriminator 1))
   ? sock_init_data_uid (arch/x86/include/asm/atomic.h:28)
   inet_create.part.0.constprop.0 (net/ipv4/af_inet.c:386)
   ? __sock_create (include/linux/rcupdate.h:347 (discriminator 1))
   __sock_create (net/socket.c:1576)
   __sys_socket (net/socket.c:1671)
   ? __pfx___sys_socket (net/socket.c:1712)
   ? do_user_addr_fault (arch/x86/mm/fault.c:1419 (discriminator 1))
   __x64_sys_socket (net/socket.c:1728)
   do_syscall_64 (arch/x86/entry/common.c:52 (discriminator 1))
   entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:130)

That's because when the socket is initialised, rcu_read_lock() is not
used despite the explicit comment written above the declaration of
mptcp_sched_find() in sched.c. Adding the missing lock/unlock avoids the
warning.

Fixes: 1730b2b ("mptcp: add sched in mptcp_sock")
Cc: [email protected]
Closes: multipath-tcp/mptcp_net-next#523
Reviewed-by: Geliang Tang <[email protected]>
Signed-off-by: Matthieu Baerts (NGI0) <[email protected]>
Reviewed-by: Simon Horman <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>
Signed-off-by: Sasha Levin <[email protected]>
mj22226 pushed a commit to mj22226/linux that referenced this pull request Nov 6, 2024
[ Upstream commit 3deb12c ]

Enabling CONFIG_PROVE_RCU_LIST with its dependence CONFIG_RCU_EXPERT
creates this splat when an MPTCP socket is created:

  =============================
  WARNING: suspicious RCU usage
  6.12.0-rc2+ torvalds#11 Not tainted
  -----------------------------
  net/mptcp/sched.c:44 RCU-list traversed in non-reader section!!

  other info that might help us debug this:

  rcu_scheduler_active = 2, debug_locks = 1
  no locks held by mptcp_connect/176.

  stack backtrace:
  CPU: 0 UID: 0 PID: 176 Comm: mptcp_connect Not tainted 6.12.0-rc2+ torvalds#11
  Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
  Call Trace:
   <TASK>
   dump_stack_lvl (lib/dump_stack.c:123)
   lockdep_rcu_suspicious (kernel/locking/lockdep.c:6822)
   mptcp_sched_find (net/mptcp/sched.c:44 (discriminator 7))
   mptcp_init_sock (net/mptcp/protocol.c:2867 (discriminator 1))
   ? sock_init_data_uid (arch/x86/include/asm/atomic.h:28)
   inet_create.part.0.constprop.0 (net/ipv4/af_inet.c:386)
   ? __sock_create (include/linux/rcupdate.h:347 (discriminator 1))
   __sock_create (net/socket.c:1576)
   __sys_socket (net/socket.c:1671)
   ? __pfx___sys_socket (net/socket.c:1712)
   ? do_user_addr_fault (arch/x86/mm/fault.c:1419 (discriminator 1))
   __x64_sys_socket (net/socket.c:1728)
   do_syscall_64 (arch/x86/entry/common.c:52 (discriminator 1))
   entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:130)

That's because when the socket is initialised, rcu_read_lock() is not
used despite the explicit comment written above the declaration of
mptcp_sched_find() in sched.c. Adding the missing lock/unlock avoids the
warning.

Fixes: 1730b2b ("mptcp: add sched in mptcp_sock")
Cc: [email protected]
Closes: multipath-tcp/mptcp_net-next#523
Reviewed-by: Geliang Tang <[email protected]>
Signed-off-by: Matthieu Baerts (NGI0) <[email protected]>
Reviewed-by: Simon Horman <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>
Signed-off-by: Sasha Levin <[email protected]>
mj22226 pushed a commit to mj22226/linux that referenced this pull request Nov 6, 2024
[ Upstream commit 3deb12c ]

Enabling CONFIG_PROVE_RCU_LIST with its dependence CONFIG_RCU_EXPERT
creates this splat when an MPTCP socket is created:

  =============================
  WARNING: suspicious RCU usage
  6.12.0-rc2+ torvalds#11 Not tainted
  -----------------------------
  net/mptcp/sched.c:44 RCU-list traversed in non-reader section!!

  other info that might help us debug this:

  rcu_scheduler_active = 2, debug_locks = 1
  no locks held by mptcp_connect/176.

  stack backtrace:
  CPU: 0 UID: 0 PID: 176 Comm: mptcp_connect Not tainted 6.12.0-rc2+ torvalds#11
  Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
  Call Trace:
   <TASK>
   dump_stack_lvl (lib/dump_stack.c:123)
   lockdep_rcu_suspicious (kernel/locking/lockdep.c:6822)
   mptcp_sched_find (net/mptcp/sched.c:44 (discriminator 7))
   mptcp_init_sock (net/mptcp/protocol.c:2867 (discriminator 1))
   ? sock_init_data_uid (arch/x86/include/asm/atomic.h:28)
   inet_create.part.0.constprop.0 (net/ipv4/af_inet.c:386)
   ? __sock_create (include/linux/rcupdate.h:347 (discriminator 1))
   __sock_create (net/socket.c:1576)
   __sys_socket (net/socket.c:1671)
   ? __pfx___sys_socket (net/socket.c:1712)
   ? do_user_addr_fault (arch/x86/mm/fault.c:1419 (discriminator 1))
   __x64_sys_socket (net/socket.c:1728)
   do_syscall_64 (arch/x86/entry/common.c:52 (discriminator 1))
   entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:130)

That's because when the socket is initialised, rcu_read_lock() is not
used despite the explicit comment written above the declaration of
mptcp_sched_find() in sched.c. Adding the missing lock/unlock avoids the
warning.

Fixes: 1730b2b ("mptcp: add sched in mptcp_sock")
Cc: [email protected]
Closes: multipath-tcp/mptcp_net-next#523
Reviewed-by: Geliang Tang <[email protected]>
Signed-off-by: Matthieu Baerts (NGI0) <[email protected]>
Reviewed-by: Simon Horman <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>
Signed-off-by: Sasha Levin <[email protected]>
mj22226 pushed a commit to mj22226/linux that referenced this pull request Nov 6, 2024
[ Upstream commit 3deb12c ]

Enabling CONFIG_PROVE_RCU_LIST with its dependence CONFIG_RCU_EXPERT
creates this splat when an MPTCP socket is created:

  =============================
  WARNING: suspicious RCU usage
  6.12.0-rc2+ torvalds#11 Not tainted
  -----------------------------
  net/mptcp/sched.c:44 RCU-list traversed in non-reader section!!

  other info that might help us debug this:

  rcu_scheduler_active = 2, debug_locks = 1
  no locks held by mptcp_connect/176.

  stack backtrace:
  CPU: 0 UID: 0 PID: 176 Comm: mptcp_connect Not tainted 6.12.0-rc2+ torvalds#11
  Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
  Call Trace:
   <TASK>
   dump_stack_lvl (lib/dump_stack.c:123)
   lockdep_rcu_suspicious (kernel/locking/lockdep.c:6822)
   mptcp_sched_find (net/mptcp/sched.c:44 (discriminator 7))
   mptcp_init_sock (net/mptcp/protocol.c:2867 (discriminator 1))
   ? sock_init_data_uid (arch/x86/include/asm/atomic.h:28)
   inet_create.part.0.constprop.0 (net/ipv4/af_inet.c:386)
   ? __sock_create (include/linux/rcupdate.h:347 (discriminator 1))
   __sock_create (net/socket.c:1576)
   __sys_socket (net/socket.c:1671)
   ? __pfx___sys_socket (net/socket.c:1712)
   ? do_user_addr_fault (arch/x86/mm/fault.c:1419 (discriminator 1))
   __x64_sys_socket (net/socket.c:1728)
   do_syscall_64 (arch/x86/entry/common.c:52 (discriminator 1))
   entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:130)

That's because when the socket is initialised, rcu_read_lock() is not
used despite the explicit comment written above the declaration of
mptcp_sched_find() in sched.c. Adding the missing lock/unlock avoids the
warning.

Fixes: 1730b2b ("mptcp: add sched in mptcp_sock")
Cc: [email protected]
Closes: multipath-tcp/mptcp_net-next#523
Reviewed-by: Geliang Tang <[email protected]>
Signed-off-by: Matthieu Baerts (NGI0) <[email protected]>
Reviewed-by: Simon Horman <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>
Signed-off-by: Sasha Levin <[email protected]>
mj22226 pushed a commit to mj22226/linux that referenced this pull request Nov 7, 2024
[ Upstream commit 3deb12c ]

Enabling CONFIG_PROVE_RCU_LIST with its dependence CONFIG_RCU_EXPERT
creates this splat when an MPTCP socket is created:

  =============================
  WARNING: suspicious RCU usage
  6.12.0-rc2+ torvalds#11 Not tainted
  -----------------------------
  net/mptcp/sched.c:44 RCU-list traversed in non-reader section!!

  other info that might help us debug this:

  rcu_scheduler_active = 2, debug_locks = 1
  no locks held by mptcp_connect/176.

  stack backtrace:
  CPU: 0 UID: 0 PID: 176 Comm: mptcp_connect Not tainted 6.12.0-rc2+ torvalds#11
  Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
  Call Trace:
   <TASK>
   dump_stack_lvl (lib/dump_stack.c:123)
   lockdep_rcu_suspicious (kernel/locking/lockdep.c:6822)
   mptcp_sched_find (net/mptcp/sched.c:44 (discriminator 7))
   mptcp_init_sock (net/mptcp/protocol.c:2867 (discriminator 1))
   ? sock_init_data_uid (arch/x86/include/asm/atomic.h:28)
   inet_create.part.0.constprop.0 (net/ipv4/af_inet.c:386)
   ? __sock_create (include/linux/rcupdate.h:347 (discriminator 1))
   __sock_create (net/socket.c:1576)
   __sys_socket (net/socket.c:1671)
   ? __pfx___sys_socket (net/socket.c:1712)
   ? do_user_addr_fault (arch/x86/mm/fault.c:1419 (discriminator 1))
   __x64_sys_socket (net/socket.c:1728)
   do_syscall_64 (arch/x86/entry/common.c:52 (discriminator 1))
   entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:130)

That's because when the socket is initialised, rcu_read_lock() is not
used despite the explicit comment written above the declaration of
mptcp_sched_find() in sched.c. Adding the missing lock/unlock avoids the
warning.

Fixes: 1730b2b ("mptcp: add sched in mptcp_sock")
Cc: [email protected]
Closes: multipath-tcp/mptcp_net-next#523
Reviewed-by: Geliang Tang <[email protected]>
Signed-off-by: Matthieu Baerts (NGI0) <[email protected]>
Reviewed-by: Simon Horman <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>
Signed-off-by: Sasha Levin <[email protected]>
1054009064 pushed a commit to 1054009064/linux that referenced this pull request Nov 8, 2024
commit e972b08 upstream.

We're seeing crashes from rq_qos_wake_function that look like this:

  BUG: unable to handle page fault for address: ffffafe180a40084
  #PF: supervisor write access in kernel mode
  #PF: error_code(0x0002) - not-present page
  PGD 100000067 P4D 100000067 PUD 10027c067 PMD 10115d067 PTE 0
  Oops: Oops: 0002 [#1] PREEMPT SMP PTI
  CPU: 17 UID: 0 PID: 0 Comm: swapper/17 Not tainted 6.12.0-rc3-00013-geca631b8fe80 torvalds#11
  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.0-0-gd239552ce722-prebuilt.qemu.org 04/01/2014
  RIP: 0010:_raw_spin_lock_irqsave+0x1d/0x40
  Code: 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 0f 1f 44 00 00 41 54 9c 41 5c fa 65 ff 05 62 97 30 4c 31 c0 ba 01 00 00 00 <f0> 0f b1 17 75 0a 4c 89 e0 41 5c c3 cc cc cc cc 89 c6 e8 2c 0b 00
  RSP: 0018:ffffafe180580ca0 EFLAGS: 00010046
  RAX: 0000000000000000 RBX: ffffafe180a3f7a8 RCX: 0000000000000011
  RDX: 0000000000000001 RSI: 0000000000000003 RDI: ffffafe180a40084
  RBP: 0000000000000000 R08: 00000000001e7240 R09: 0000000000000011
  R10: 0000000000000028 R11: 0000000000000888 R12: 0000000000000002
  R13: ffffafe180a40084 R14: 0000000000000000 R15: 0000000000000003
  FS:  0000000000000000(0000) GS:ffff9aaf1f280000(0000) knlGS:0000000000000000
  CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
  CR2: ffffafe180a40084 CR3: 000000010e428002 CR4: 0000000000770ef0
  DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
  DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
  PKRU: 55555554
  Call Trace:
   <IRQ>
   try_to_wake_up+0x5a/0x6a0
   rq_qos_wake_function+0x71/0x80
   __wake_up_common+0x75/0xa0
   __wake_up+0x36/0x60
   scale_up.part.0+0x50/0x110
   wb_timer_fn+0x227/0x450
   ...

So rq_qos_wake_function() calls wake_up_process(data->task), which calls
try_to_wake_up(), which faults in raw_spin_lock_irqsave(&p->pi_lock).

p comes from data->task, and data comes from the waitqueue entry, which
is stored on the waiter's stack in rq_qos_wait(). Analyzing the core
dump with drgn, I found that the waiter had already woken up and moved
on to a completely unrelated code path, clobbering what was previously
data->task. Meanwhile, the waker was passing the clobbered garbage in
data->task to wake_up_process(), leading to the crash.

What's happening is that in between rq_qos_wake_function() deleting the
waitqueue entry and calling wake_up_process(), rq_qos_wait() is finding
that it already got a token and returning. The race looks like this:

rq_qos_wait()                           rq_qos_wake_function()
==============================================================
prepare_to_wait_exclusive()
                                        data->got_token = true;
                                        list_del_init(&curr->entry);
if (data.got_token)
        break;
finish_wait(&rqw->wait, &data.wq);
  ^- returns immediately because
     list_empty_careful(&wq_entry->entry)
     is true
... return, go do something else ...
                                        wake_up_process(data->task)
                                          (NO LONGER VALID!)-^

Normally, finish_wait() is supposed to synchronize against the waker.
But, as noted above, it is returning immediately because the waitqueue
entry has already been removed from the waitqueue.

The bug is that rq_qos_wake_function() is accessing the waitqueue entry
AFTER deleting it. Note that autoremove_wake_function() wakes the waiter
and THEN deletes the waitqueue entry, which is the proper order.

Fix it by swapping the order. We also need to use
list_del_init_careful() to match the list_empty_careful() in
finish_wait().

Fixes: 38cfb5a ("blk-wbt: improve waking of tasks")
Cc: [email protected]
Signed-off-by: Omar Sandoval <[email protected]>
Acked-by: Tejun Heo <[email protected]>
Reviewed-by: Johannes Thumshirn <[email protected]>
Link: https://lore.kernel.org/r/d3bee2463a67b1ee597211823bf7ad3721c26e41.1729014591.git.osandov@fb.com
Signed-off-by: Jens Axboe <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
hellsgod pushed a commit to hellsgod/linux that referenced this pull request Nov 8, 2024
[ Upstream commit 3deb12c ]

Enabling CONFIG_PROVE_RCU_LIST with its dependence CONFIG_RCU_EXPERT
creates this splat when an MPTCP socket is created:

  =============================
  WARNING: suspicious RCU usage
  6.12.0-rc2+ torvalds#11 Not tainted
  -----------------------------
  net/mptcp/sched.c:44 RCU-list traversed in non-reader section!!

  other info that might help us debug this:

  rcu_scheduler_active = 2, debug_locks = 1
  no locks held by mptcp_connect/176.

  stack backtrace:
  CPU: 0 UID: 0 PID: 176 Comm: mptcp_connect Not tainted 6.12.0-rc2+ torvalds#11
  Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
  Call Trace:
   <TASK>
   dump_stack_lvl (lib/dump_stack.c:123)
   lockdep_rcu_suspicious (kernel/locking/lockdep.c:6822)
   mptcp_sched_find (net/mptcp/sched.c:44 (discriminator 7))
   mptcp_init_sock (net/mptcp/protocol.c:2867 (discriminator 1))
   ? sock_init_data_uid (arch/x86/include/asm/atomic.h:28)
   inet_create.part.0.constprop.0 (net/ipv4/af_inet.c:386)
   ? __sock_create (include/linux/rcupdate.h:347 (discriminator 1))
   __sock_create (net/socket.c:1576)
   __sys_socket (net/socket.c:1671)
   ? __pfx___sys_socket (net/socket.c:1712)
   ? do_user_addr_fault (arch/x86/mm/fault.c:1419 (discriminator 1))
   __x64_sys_socket (net/socket.c:1728)
   do_syscall_64 (arch/x86/entry/common.c:52 (discriminator 1))
   entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:130)

That's because when the socket is initialised, rcu_read_lock() is not
used despite the explicit comment written above the declaration of
mptcp_sched_find() in sched.c. Adding the missing lock/unlock avoids the
warning.

Fixes: 1730b2b ("mptcp: add sched in mptcp_sock")
Cc: [email protected]
Closes: multipath-tcp/mptcp_net-next#523
Reviewed-by: Geliang Tang <[email protected]>
Signed-off-by: Matthieu Baerts (NGI0) <[email protected]>
Reviewed-by: Simon Horman <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>
Signed-off-by: Sasha Levin <[email protected]>
1054009064 pushed a commit to 1054009064/linux that referenced this pull request Nov 8, 2024
[ Upstream commit 3deb12c ]

Enabling CONFIG_PROVE_RCU_LIST with its dependence CONFIG_RCU_EXPERT
creates this splat when an MPTCP socket is created:

  =============================
  WARNING: suspicious RCU usage
  6.12.0-rc2+ torvalds#11 Not tainted
  -----------------------------
  net/mptcp/sched.c:44 RCU-list traversed in non-reader section!!

  other info that might help us debug this:

  rcu_scheduler_active = 2, debug_locks = 1
  no locks held by mptcp_connect/176.

  stack backtrace:
  CPU: 0 UID: 0 PID: 176 Comm: mptcp_connect Not tainted 6.12.0-rc2+ torvalds#11
  Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
  Call Trace:
   <TASK>
   dump_stack_lvl (lib/dump_stack.c:123)
   lockdep_rcu_suspicious (kernel/locking/lockdep.c:6822)
   mptcp_sched_find (net/mptcp/sched.c:44 (discriminator 7))
   mptcp_init_sock (net/mptcp/protocol.c:2867 (discriminator 1))
   ? sock_init_data_uid (arch/x86/include/asm/atomic.h:28)
   inet_create.part.0.constprop.0 (net/ipv4/af_inet.c:386)
   ? __sock_create (include/linux/rcupdate.h:347 (discriminator 1))
   __sock_create (net/socket.c:1576)
   __sys_socket (net/socket.c:1671)
   ? __pfx___sys_socket (net/socket.c:1712)
   ? do_user_addr_fault (arch/x86/mm/fault.c:1419 (discriminator 1))
   __x64_sys_socket (net/socket.c:1728)
   do_syscall_64 (arch/x86/entry/common.c:52 (discriminator 1))
   entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:130)

That's because when the socket is initialised, rcu_read_lock() is not
used despite the explicit comment written above the declaration of
mptcp_sched_find() in sched.c. Adding the missing lock/unlock avoids the
warning.

Fixes: 1730b2b ("mptcp: add sched in mptcp_sock")
Cc: [email protected]
Closes: multipath-tcp/mptcp_net-next#523
Reviewed-by: Geliang Tang <[email protected]>
Signed-off-by: Matthieu Baerts (NGI0) <[email protected]>
Reviewed-by: Simon Horman <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>
Signed-off-by: Sasha Levin <[email protected]>
intel-lab-lkp pushed a commit to intel-lab-lkp/linux that referenced this pull request Nov 12, 2024
This commit provides a watchdog timer that sets a limit of how long a
single sub-test could run:
- if sub-test runs for 10 seconds, the name of the test is printed
  (currently the name of the test is printed only after it finishes);
- if sub-test runs for 120 seconds, the running thread is terminated
  with SIGSEGV (to trigger crash_handler() and get a stack trace).

Specifically:
- the timer is armed on each call to run_one_test();
- re-armed at each call to test__start_subtest();
- is stopped when exiting run_one_test().

Default timeout could be overridden using '-w' or '--watchdog-timeout'
options. Value 0 can be used to turn the timer off.
Here is an example execution:

    $ ./ssh-exec.sh ./test_progs -w 5 -t \
      send_signal/send_signal_perf_thread_remote,send_signal/send_signal_nmi_thread_remote
    WATCHDOG: test case send_signal/send_signal_nmi_thread_remote executes for 5 seconds, terminating with SIGSEGV
    Caught signal torvalds#11!
    Stack trace:
    ./test_progs(crash_handler+0x1f)[0x9049ef]
    /lib64/libc.so.6(+0x40d00)[0x7f1f1184fd00]
    /lib64/libc.so.6(read+0x4a)[0x7f1f1191cc4a]
    ./test_progs[0x720dd3]
    ./test_progs[0x71ef7a]
    ./test_progs(test_send_signal+0x1db)[0x71edeb]
    ./test_progs[0x9066c5]
    ./test_progs(main+0x5ed)[0x9054ad]
    /lib64/libc.so.6(+0x2a088)[0x7f1f11839088]
    /lib64/libc.so.6(__libc_start_main+0x8b)[0x7f1f1183914b]
    ./test_progs(_start+0x25)[0x527385]
    torvalds#292     send_signal:FAIL
    test_send_signal_common:PASS:reading pipe 0 nsec
    test_send_signal_common:PASS:reading pipe error: size 0 0 nsec
    test_send_signal_common:PASS:incorrect result 0 nsec
    test_send_signal_common:PASS:pipe_write 0 nsec
    test_send_signal_common:PASS:setpriority 0 nsec

Timer is implemented using timer_{create,start} librt API.
Internally librt uses pthreads for SIGEV_THREAD timers,
so this change adds a background timer thread to the test process.
Because of this a few checks in tests 'bpf_iter' and 'iters'
need an update to account for an extra thread.

For parallelized scenario the watchdog is also created for each worker
fork. If one of the workers gets stuck, it would be terminated by a
watchdog. In theory, this might lead to a scenario when all worker
threads are exhausted, however this should not be a problem for
server_main(), as it would exit with some of the tests not run.

Signed-off-by: Eduard Zingerman <[email protected]>
intel-lab-lkp pushed a commit to intel-lab-lkp/linux that referenced this pull request Nov 12, 2024
This commit provides a watchdog timer that sets a limit of how long a
single sub-test could run:
- if sub-test runs for 10 seconds, the name of the test is printed
  (currently the name of the test is printed only after it finishes);
- if sub-test runs for 120 seconds, the running thread is terminated
  with SIGSEGV (to trigger crash_handler() and get a stack trace).

Specifically:
- the timer is armed on each call to run_one_test();
- re-armed at each call to test__start_subtest();
- is stopped when exiting run_one_test().

Default timeout could be overridden using '-w' or '--watchdog-timeout'
options. Value 0 can be used to turn the timer off.
Here is an example execution:

    $ ./ssh-exec.sh ./test_progs -w 5 -t \
      send_signal/send_signal_perf_thread_remote,send_signal/send_signal_nmi_thread_remote
    WATCHDOG: test case send_signal/send_signal_nmi_thread_remote executes for 5 seconds, terminating with SIGSEGV
    Caught signal torvalds#11!
    Stack trace:
    ./test_progs(crash_handler+0x1f)[0x9049ef]
    /lib64/libc.so.6(+0x40d00)[0x7f1f1184fd00]
    /lib64/libc.so.6(read+0x4a)[0x7f1f1191cc4a]
    ./test_progs[0x720dd3]
    ./test_progs[0x71ef7a]
    ./test_progs(test_send_signal+0x1db)[0x71edeb]
    ./test_progs[0x9066c5]
    ./test_progs(main+0x5ed)[0x9054ad]
    /lib64/libc.so.6(+0x2a088)[0x7f1f11839088]
    /lib64/libc.so.6(__libc_start_main+0x8b)[0x7f1f1183914b]
    ./test_progs(_start+0x25)[0x527385]
    torvalds#292     send_signal:FAIL
    test_send_signal_common:PASS:reading pipe 0 nsec
    test_send_signal_common:PASS:reading pipe error: size 0 0 nsec
    test_send_signal_common:PASS:incorrect result 0 nsec
    test_send_signal_common:PASS:pipe_write 0 nsec
    test_send_signal_common:PASS:setpriority 0 nsec

Timer is implemented using timer_{create,start} librt API.
Internally librt uses pthreads for SIGEV_THREAD timers,
so this change adds a background timer thread to the test process.
Because of this a few checks in tests 'bpf_iter' and 'iters'
need an update to account for an extra thread.

For parallelized scenario the watchdog is also created for each worker
fork. If one of the workers gets stuck, it would be terminated by a
watchdog. In theory, this might lead to a scenario when all worker
threads are exhausted, however this should not be a problem for
server_main(), as it would exit with some of the tests not run.

Signed-off-by: Eduard Zingerman <[email protected]>
intel-lab-lkp pushed a commit to intel-lab-lkp/linux that referenced this pull request Nov 13, 2024
This commit provides a watchdog timer that sets a limit of how long a
single sub-test could run:
- if sub-test runs for 10 seconds, the name of the test is printed
  (currently the name of the test is printed only after it finishes);
- if sub-test runs for 120 seconds, the running thread is terminated
  with SIGSEGV (to trigger crash_handler() and get a stack trace).

Specifically:
- the timer is armed on each call to run_one_test();
- re-armed at each call to test__start_subtest();
- is stopped when exiting run_one_test().

Default timeout could be overridden using '-w' or '--watchdog-timeout'
options. Value 0 can be used to turn the timer off.
Here is an example execution:

    $ ./ssh-exec.sh ./test_progs -w 5 -t \
      send_signal/send_signal_perf_thread_remote,send_signal/send_signal_nmi_thread_remote
    WATCHDOG: test case send_signal/send_signal_nmi_thread_remote executes for 5 seconds, terminating with SIGSEGV
    Caught signal torvalds#11!
    Stack trace:
    ./test_progs(crash_handler+0x1f)[0x9049ef]
    /lib64/libc.so.6(+0x40d00)[0x7f1f1184fd00]
    /lib64/libc.so.6(read+0x4a)[0x7f1f1191cc4a]
    ./test_progs[0x720dd3]
    ./test_progs[0x71ef7a]
    ./test_progs(test_send_signal+0x1db)[0x71edeb]
    ./test_progs[0x9066c5]
    ./test_progs(main+0x5ed)[0x9054ad]
    /lib64/libc.so.6(+0x2a088)[0x7f1f11839088]
    /lib64/libc.so.6(__libc_start_main+0x8b)[0x7f1f1183914b]
    ./test_progs(_start+0x25)[0x527385]
    torvalds#292     send_signal:FAIL
    test_send_signal_common:PASS:reading pipe 0 nsec
    test_send_signal_common:PASS:reading pipe error: size 0 0 nsec
    test_send_signal_common:PASS:incorrect result 0 nsec
    test_send_signal_common:PASS:pipe_write 0 nsec
    test_send_signal_common:PASS:setpriority 0 nsec

Timer is implemented using timer_{create,start} librt API.
Internally librt uses pthreads for SIGEV_THREAD timers,
so this change adds a background timer thread to the test process.
Because of this a few checks in tests 'bpf_iter' and 'iters'
need an update to account for an extra thread.

For parallelized scenario the watchdog is also created for each worker
fork. If one of the workers gets stuck, it would be terminated by a
watchdog. In theory, this might lead to a scenario when all worker
threads are exhausted, however this should not be a problem for
server_main(), as it would exit with some of the tests not run.

Signed-off-by: Eduard Zingerman <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Alexei Starovoitov <[email protected]>
MingcongBai pushed a commit to AOSC-Tracking/linux that referenced this pull request Nov 13, 2024
[ Upstream commit 3deb12c ]

Enabling CONFIG_PROVE_RCU_LIST with its dependence CONFIG_RCU_EXPERT
creates this splat when an MPTCP socket is created:

  =============================
  WARNING: suspicious RCU usage
  6.12.0-rc2+ torvalds#11 Not tainted
  -----------------------------
  net/mptcp/sched.c:44 RCU-list traversed in non-reader section!!

  other info that might help us debug this:

  rcu_scheduler_active = 2, debug_locks = 1
  no locks held by mptcp_connect/176.

  stack backtrace:
  CPU: 0 UID: 0 PID: 176 Comm: mptcp_connect Not tainted 6.12.0-rc2+ torvalds#11
  Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
  Call Trace:
   <TASK>
   dump_stack_lvl (lib/dump_stack.c:123)
   lockdep_rcu_suspicious (kernel/locking/lockdep.c:6822)
   mptcp_sched_find (net/mptcp/sched.c:44 (discriminator 7))
   mptcp_init_sock (net/mptcp/protocol.c:2867 (discriminator 1))
   ? sock_init_data_uid (arch/x86/include/asm/atomic.h:28)
   inet_create.part.0.constprop.0 (net/ipv4/af_inet.c:386)
   ? __sock_create (include/linux/rcupdate.h:347 (discriminator 1))
   __sock_create (net/socket.c:1576)
   __sys_socket (net/socket.c:1671)
   ? __pfx___sys_socket (net/socket.c:1712)
   ? do_user_addr_fault (arch/x86/mm/fault.c:1419 (discriminator 1))
   __x64_sys_socket (net/socket.c:1728)
   do_syscall_64 (arch/x86/entry/common.c:52 (discriminator 1))
   entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:130)

That's because when the socket is initialised, rcu_read_lock() is not
used despite the explicit comment written above the declaration of
mptcp_sched_find() in sched.c. Adding the missing lock/unlock avoids the
warning.

Fixes: 1730b2b ("mptcp: add sched in mptcp_sock")
Cc: [email protected]
Closes: multipath-tcp/mptcp_net-next#523
Reviewed-by: Geliang Tang <[email protected]>
Signed-off-by: Matthieu Baerts (NGI0) <[email protected]>
Reviewed-by: Simon Horman <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>
Signed-off-by: Sasha Levin <[email protected]>
roxell added a commit to roxell/linux that referenced this pull request Nov 15, 2024
[  123.491737][    T1] Unexpected kernel BRK exception at EL1
[  123.497593][    T1] Internal error: ptrace BRK handler: f20003e8 [#1] PREEMPT SMP
[  123.500785][    T1] Modules linked in:
[  123.502567][    T1] CPU: 0 PID: 1 Comm: swapper/0 Tainted: G        W         5.8.0-rc3-next-20200630-00003-g15e24419c239-dirty torvalds#11
[  123.507468][    T1] Hardware name: linux,dummy-virt (DT)
[  123.509826][    T1] pstate: 80400005 (Nzcv daif +PAN -UAO BTYPE=--)
[  123.512609][    T1] pc : of_unittest_untrack_overlay+0x64/0x134
[  123.515245][    T1] lr : of_unittest_untrack_overlay+0x64/0x134
[  123.517848][    T1] sp : ffff00006a65fb30
[  123.519668][    T1] x29: ffff00006a65fb30 x28: 0000000000000000
[  123.522295][    T1] x27: ffff00006a65fc30 x26: ffffa00016b86f00
[  123.524937][    T1] x25: 0000000000000000 x24: 0000000000000000
[  123.527592][    T1] x23: ffffa00014c72540 x22: ffffa00016b86000
[  123.530191][    T1] x21: 0000000000000000 x20: 00000000ffffffff
[  123.532845][    T1] x19: 00000000ffffffff x18: 0000000000002690
[  123.535547][    T1] x17: 0000000000002718 x16: 00000000000014b8
[  123.538299][    T1] x15: 0000000000000001 x14: 0080000000000000
[  123.541055][    T1] x13: 0000000000000002 x12: ffff94000298d209
[  123.543801][    T1] x11: 1ffff4000298d208 x10: ffff94000298d208
[  123.546580][    T1] x9 : dfffa00000000000 x8 : ffffa00014c69047
[  123.549247][    T1] x7 : 0000000000000001 x6 : ffffa00014c69040
[  123.552026][    T1] x5 : ffff00006a654040 x4 : 0000000000000000
[  123.554799][    T1] x3 : ffffa00011d59d04 x2 : 00000000ffffffff
[  123.557541][    T1] x1 : ffff00006a654040 x0 : 0000000000000000
[  123.560390][    T1] Call trace:
[  123.561935][    T1]  of_unittest_untrack_overlay+0x64/0x134
[  123.564469][    T1]  of_unittest+0x2220/0x2438
[  123.566585][    T1]  do_one_initcall+0x470/0xa10
[  123.568751][    T1]  kernel_init_freeable+0x510/0x5f0
[  123.571123][    T1]  kernel_init+0x18/0x1e8
[  123.573078][    T1]  ret_from_fork+0x10/0x18
[  123.575119][    T1] Code: 97978a9c d4210000 14000024 97978a99 (d4207d00)
[  123.578138][    T1] ---[ end trace c4e049fb5e3b0ba0 ]---
[  123.580449][    T1] Kernel panic - not syncing: Fatal exception
[  123.583116][    T1] Kernel Offset: disabled
[  123.585066][    T1] CPU features: 0x240002,20002004
[  123.587259][    T1] Memory Limit: none
[  123.588986][    T1] ---[ end Kernel panic - not syncing: Fatal exception ]---

Signed-off-by: Anders Roxell <[email protected]>
roxell added a commit to roxell/linux that referenced this pull request Nov 18, 2024
[  123.491737][    T1] Unexpected kernel BRK exception at EL1
[  123.497593][    T1] Internal error: ptrace BRK handler: f20003e8 [#1] PREEMPT SMP
[  123.500785][    T1] Modules linked in:
[  123.502567][    T1] CPU: 0 PID: 1 Comm: swapper/0 Tainted: G        W         5.8.0-rc3-next-20200630-00003-g15e24419c239-dirty torvalds#11
[  123.507468][    T1] Hardware name: linux,dummy-virt (DT)
[  123.509826][    T1] pstate: 80400005 (Nzcv daif +PAN -UAO BTYPE=--)
[  123.512609][    T1] pc : of_unittest_untrack_overlay+0x64/0x134
[  123.515245][    T1] lr : of_unittest_untrack_overlay+0x64/0x134
[  123.517848][    T1] sp : ffff00006a65fb30
[  123.519668][    T1] x29: ffff00006a65fb30 x28: 0000000000000000
[  123.522295][    T1] x27: ffff00006a65fc30 x26: ffffa00016b86f00
[  123.524937][    T1] x25: 0000000000000000 x24: 0000000000000000
[  123.527592][    T1] x23: ffffa00014c72540 x22: ffffa00016b86000
[  123.530191][    T1] x21: 0000000000000000 x20: 00000000ffffffff
[  123.532845][    T1] x19: 00000000ffffffff x18: 0000000000002690
[  123.535547][    T1] x17: 0000000000002718 x16: 00000000000014b8
[  123.538299][    T1] x15: 0000000000000001 x14: 0080000000000000
[  123.541055][    T1] x13: 0000000000000002 x12: ffff94000298d209
[  123.543801][    T1] x11: 1ffff4000298d208 x10: ffff94000298d208
[  123.546580][    T1] x9 : dfffa00000000000 x8 : ffffa00014c69047
[  123.549247][    T1] x7 : 0000000000000001 x6 : ffffa00014c69040
[  123.552026][    T1] x5 : ffff00006a654040 x4 : 0000000000000000
[  123.554799][    T1] x3 : ffffa00011d59d04 x2 : 00000000ffffffff
[  123.557541][    T1] x1 : ffff00006a654040 x0 : 0000000000000000
[  123.560390][    T1] Call trace:
[  123.561935][    T1]  of_unittest_untrack_overlay+0x64/0x134
[  123.564469][    T1]  of_unittest+0x2220/0x2438
[  123.566585][    T1]  do_one_initcall+0x470/0xa10
[  123.568751][    T1]  kernel_init_freeable+0x510/0x5f0
[  123.571123][    T1]  kernel_init+0x18/0x1e8
[  123.573078][    T1]  ret_from_fork+0x10/0x18
[  123.575119][    T1] Code: 97978a9c d4210000 14000024 97978a99 (d4207d00)
[  123.578138][    T1] ---[ end trace c4e049fb5e3b0ba0 ]---
[  123.580449][    T1] Kernel panic - not syncing: Fatal exception
[  123.583116][    T1] Kernel Offset: disabled
[  123.585066][    T1] CPU features: 0x240002,20002004
[  123.587259][    T1] Memory Limit: none
[  123.588986][    T1] ---[ end Kernel panic - not syncing: Fatal exception ]---

Signed-off-by: Anders Roxell <[email protected]>
mj22226 pushed a commit to mj22226/linux that referenced this pull request Nov 20, 2024
commit 5b188cc upstream.

Disable strict aliasing, as has been done in the kernel proper for decades
(literally since before git history) to fix issues where gcc will optimize
away loads in code that looks 100% correct, but is _technically_ undefined
behavior, and thus can be thrown away by the compiler.

E.g. arm64's vPMU counter access test casts a uint64_t (unsigned long)
pointer to a u64 (unsigned long long) pointer when setting PMCR.N via
u64p_replace_bits(), which gcc-13 detects and optimizes away, i.e. ignores
the result and uses the original PMCR.

The issue is most easily observed by making set_pmcr_n() noinline and
wrapping the call with printf(), e.g. sans comments, for this code:

  printf("orig = %lx, next = %lx, want = %lu\n", pmcr_orig, pmcr, pmcr_n);
  set_pmcr_n(&pmcr, pmcr_n);
  printf("orig = %lx, next = %lx, want = %lu\n", pmcr_orig, pmcr, pmcr_n);

gcc-13 generates:

 0000000000401c90 <set_pmcr_n>:
  401c90:       f9400002        ldr     x2, [x0]
  401c94:       b3751022        bfi     x2, x1, torvalds#11, #5
  401c98:       f9000002        str     x2, [x0]
  401c9c:       d65f03c0        ret

 0000000000402660 <test_create_vpmu_vm_with_pmcr_n>:
  402724:       aa1403e3        mov     x3, x20
  402728:       aa1503e2        mov     x2, x21
  40272c:       aa1603e0        mov     x0, x22
  402730:       aa1503e1        mov     x1, x21
  402734:       940060ff        bl      41ab30 <_IO_printf>
  402738:       aa1403e1        mov     x1, x20
  40273c:       910183e0        add     x0, sp, #0x60
  402740:       97fffd54        bl      401c90 <set_pmcr_n>
  402744:       aa1403e3        mov     x3, x20
  402748:       aa1503e2        mov     x2, x21
  40274c:       aa1503e1        mov     x1, x21
  402750:       aa1603e0        mov     x0, x22
  402754:       940060f7        bl      41ab30 <_IO_printf>

with the value stored in [sp + 0x60] ignored by both printf() above and
in the test proper, resulting in a false failure due to vcpu_set_reg()
simply storing the original value, not the intended value.

  $ ./vpmu_counter_access
  Random seed: 0x6b8b4567
  orig = 3040, next = 3040, want = 0
  orig = 3040, next = 3040, want = 0
  ==== Test Assertion Failure ====
    aarch64/vpmu_counter_access.c:505: pmcr_n == get_pmcr_n(pmcr)
    pid=71578 tid=71578 errno=9 - Bad file descriptor
       1        0x400673: run_access_test at vpmu_counter_access.c:522
       2         (inlined by) main at vpmu_counter_access.c:643
       3        0x4132d7: __libc_start_call_main at libc-start.o:0
       4        0x413653: __libc_start_main at ??:0
       5        0x40106f: _start at ??:0
    Failed to update PMCR.N to 0 (received: 6)

Somewhat bizarrely, gcc-11 also exhibits the same behavior, but only if
set_pmcr_n() is marked noinline, whereas gcc-13 fails even if set_pmcr_n()
is inlined in its sole caller.

Cc: [email protected]
Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=116912
Signed-off-by: Sean Christopherson <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
roxell added a commit to roxell/linux that referenced this pull request Nov 20, 2024
[  123.491737][    T1] Unexpected kernel BRK exception at EL1
[  123.497593][    T1] Internal error: ptrace BRK handler: f20003e8 [#1] PREEMPT SMP
[  123.500785][    T1] Modules linked in:
[  123.502567][    T1] CPU: 0 PID: 1 Comm: swapper/0 Tainted: G        W         5.8.0-rc3-next-20200630-00003-g15e24419c239-dirty torvalds#11
[  123.507468][    T1] Hardware name: linux,dummy-virt (DT)
[  123.509826][    T1] pstate: 80400005 (Nzcv daif +PAN -UAO BTYPE=--)
[  123.512609][    T1] pc : of_unittest_untrack_overlay+0x64/0x134
[  123.515245][    T1] lr : of_unittest_untrack_overlay+0x64/0x134
[  123.517848][    T1] sp : ffff00006a65fb30
[  123.519668][    T1] x29: ffff00006a65fb30 x28: 0000000000000000
[  123.522295][    T1] x27: ffff00006a65fc30 x26: ffffa00016b86f00
[  123.524937][    T1] x25: 0000000000000000 x24: 0000000000000000
[  123.527592][    T1] x23: ffffa00014c72540 x22: ffffa00016b86000
[  123.530191][    T1] x21: 0000000000000000 x20: 00000000ffffffff
[  123.532845][    T1] x19: 00000000ffffffff x18: 0000000000002690
[  123.535547][    T1] x17: 0000000000002718 x16: 00000000000014b8
[  123.538299][    T1] x15: 0000000000000001 x14: 0080000000000000
[  123.541055][    T1] x13: 0000000000000002 x12: ffff94000298d209
[  123.543801][    T1] x11: 1ffff4000298d208 x10: ffff94000298d208
[  123.546580][    T1] x9 : dfffa00000000000 x8 : ffffa00014c69047
[  123.549247][    T1] x7 : 0000000000000001 x6 : ffffa00014c69040
[  123.552026][    T1] x5 : ffff00006a654040 x4 : 0000000000000000
[  123.554799][    T1] x3 : ffffa00011d59d04 x2 : 00000000ffffffff
[  123.557541][    T1] x1 : ffff00006a654040 x0 : 0000000000000000
[  123.560390][    T1] Call trace:
[  123.561935][    T1]  of_unittest_untrack_overlay+0x64/0x134
[  123.564469][    T1]  of_unittest+0x2220/0x2438
[  123.566585][    T1]  do_one_initcall+0x470/0xa10
[  123.568751][    T1]  kernel_init_freeable+0x510/0x5f0
[  123.571123][    T1]  kernel_init+0x18/0x1e8
[  123.573078][    T1]  ret_from_fork+0x10/0x18
[  123.575119][    T1] Code: 97978a9c d4210000 14000024 97978a99 (d4207d00)
[  123.578138][    T1] ---[ end trace c4e049fb5e3b0ba0 ]---
[  123.580449][    T1] Kernel panic - not syncing: Fatal exception
[  123.583116][    T1] Kernel Offset: disabled
[  123.585066][    T1] CPU features: 0x240002,20002004
[  123.587259][    T1] Memory Limit: none
[  123.588986][    T1] ---[ end Kernel panic - not syncing: Fatal exception ]---

Signed-off-by: Anders Roxell <[email protected]>
intel-lab-lkp pushed a commit to intel-lab-lkp/linux that referenced this pull request Nov 21, 2024
commit cf96b8e upstream.

ASan reports a memory leak caused by evlist not being deleted on exit in
perf-report, perf-script and perf-data.
The problem is caused by evlist->session not being deleted, which is
allocated in perf_session__read_header, called in perf_session__new if
perf_data is in read mode.
In case of write mode, the session->evlist is filled by the caller.
This patch solves the problem by calling evlist__delete in
perf_session__delete if perf_data is in read mode.

Changes in v2:
 - call evlist__delete from within perf_session__delete

v1: https://lore.kernel.org/lkml/[email protected]/

ASan report follows:

$ ./perf script report flamegraph
=================================================================
==227640==ERROR: LeakSanitizer: detected memory leaks

<SNIP unrelated>

Indirect leak of 2704 byte(s) in 1 object(s) allocated from:
    #0 0x4f4137 in calloc (/home/user/linux/tools/perf/perf+0x4f4137)
    #1 0xbe3d56 in zalloc /home/user/linux/tools/lib/perf/../../lib/zalloc.c:8:9
    #2 0x7f999e in evlist__new /home/user/linux/tools/perf/util/evlist.c:77:26
    #3 0x8ad938 in perf_session__read_header /home/user/linux/tools/perf/util/header.c:3797:20
    #4 0x8ec714 in perf_session__open /home/user/linux/tools/perf/util/session.c:109:6
    #5 0x8ebe83 in perf_session__new /home/user/linux/tools/perf/util/session.c:213:10
    torvalds#6 0x60c6de in cmd_script /home/user/linux/tools/perf/builtin-script.c:3856:12
    torvalds#7 0x7b2930 in run_builtin /home/user/linux/tools/perf/perf.c:313:11
    torvalds#8 0x7b120f in handle_internal_command /home/user/linux/tools/perf/perf.c:365:8
    torvalds#9 0x7b2493 in run_argv /home/user/linux/tools/perf/perf.c:409:2
    torvalds#10 0x7b0c89 in main /home/user/linux/tools/perf/perf.c:539:3
    torvalds#11 0x7f5260654b74  (/lib64/libc.so.6+0x27b74)

Indirect leak of 568 byte(s) in 1 object(s) allocated from:
    #0 0x4f4137 in calloc (/home/user/linux/tools/perf/perf+0x4f4137)
    #1 0xbe3d56 in zalloc /home/user/linux/tools/lib/perf/../../lib/zalloc.c:8:9
    #2 0x80ce88 in evsel__new_idx /home/user/linux/tools/perf/util/evsel.c:268:24
    #3 0x8aed93 in evsel__new /home/user/linux/tools/perf/util/evsel.h:210:9
    #4 0x8ae07e in perf_session__read_header /home/user/linux/tools/perf/util/header.c:3853:11
    #5 0x8ec714 in perf_session__open /home/user/linux/tools/perf/util/session.c:109:6
    torvalds#6 0x8ebe83 in perf_session__new /home/user/linux/tools/perf/util/session.c:213:10
    torvalds#7 0x60c6de in cmd_script /home/user/linux/tools/perf/builtin-script.c:3856:12
    torvalds#8 0x7b2930 in run_builtin /home/user/linux/tools/perf/perf.c:313:11
    torvalds#9 0x7b120f in handle_internal_command /home/user/linux/tools/perf/perf.c:365:8
    torvalds#10 0x7b2493 in run_argv /home/user/linux/tools/perf/perf.c:409:2
    torvalds#11 0x7b0c89 in main /home/user/linux/tools/perf/perf.c:539:3
    torvalds#12 0x7f5260654b74  (/lib64/libc.so.6+0x27b74)

Indirect leak of 264 byte(s) in 1 object(s) allocated from:
    #0 0x4f4137 in calloc (/home/user/linux/tools/perf/perf+0x4f4137)
    #1 0xbe3d56 in zalloc /home/user/linux/tools/lib/perf/../../lib/zalloc.c:8:9
    #2 0xbe3e70 in xyarray__new /home/user/linux/tools/lib/perf/xyarray.c:10:23
    #3 0xbd7754 in perf_evsel__alloc_id /home/user/linux/tools/lib/perf/evsel.c:361:21
    #4 0x8ae201 in perf_session__read_header /home/user/linux/tools/perf/util/header.c:3871:7
    #5 0x8ec714 in perf_session__open /home/user/linux/tools/perf/util/session.c:109:6
    torvalds#6 0x8ebe83 in perf_session__new /home/user/linux/tools/perf/util/session.c:213:10
    torvalds#7 0x60c6de in cmd_script /home/user/linux/tools/perf/builtin-script.c:3856:12
    torvalds#8 0x7b2930 in run_builtin /home/user/linux/tools/perf/perf.c:313:11
    torvalds#9 0x7b120f in handle_internal_command /home/user/linux/tools/perf/perf.c:365:8
    torvalds#10 0x7b2493 in run_argv /home/user/linux/tools/perf/perf.c:409:2
    torvalds#11 0x7b0c89 in main /home/user/linux/tools/perf/perf.c:539:3
    torvalds#12 0x7f5260654b74  (/lib64/libc.so.6+0x27b74)

Indirect leak of 32 byte(s) in 1 object(s) allocated from:
    #0 0x4f4137 in calloc (/home/user/linux/tools/perf/perf+0x4f4137)
    #1 0xbe3d56 in zalloc /home/user/linux/tools/lib/perf/../../lib/zalloc.c:8:9
    #2 0xbd77e0 in perf_evsel__alloc_id /home/user/linux/tools/lib/perf/evsel.c:365:14
    #3 0x8ae201 in perf_session__read_header /home/user/linux/tools/perf/util/header.c:3871:7
    #4 0x8ec714 in perf_session__open /home/user/linux/tools/perf/util/session.c:109:6
    #5 0x8ebe83 in perf_session__new /home/user/linux/tools/perf/util/session.c:213:10
    torvalds#6 0x60c6de in cmd_script /home/user/linux/tools/perf/builtin-script.c:3856:12
    torvalds#7 0x7b2930 in run_builtin /home/user/linux/tools/perf/perf.c:313:11
    torvalds#8 0x7b120f in handle_internal_command /home/user/linux/tools/perf/perf.c:365:8
    torvalds#9 0x7b2493 in run_argv /home/user/linux/tools/perf/perf.c:409:2
    torvalds#10 0x7b0c89 in main /home/user/linux/tools/perf/perf.c:539:3
    torvalds#11 0x7f5260654b74  (/lib64/libc.so.6+0x27b74)

Indirect leak of 7 byte(s) in 1 object(s) allocated from:
    #0 0x4b8207 in strdup (/home/user/linux/tools/perf/perf+0x4b8207)
    #1 0x8b4459 in evlist__set_event_name /home/user/linux/tools/perf/util/header.c:2292:16
    #2 0x89d862 in process_event_desc /home/user/linux/tools/perf/util/header.c:2313:3
    #3 0x8af319 in perf_file_section__process /home/user/linux/tools/perf/util/header.c:3651:9
    #4 0x8aa6e9 in perf_header__process_sections /home/user/linux/tools/perf/util/header.c:3427:9
    #5 0x8ae3e7 in perf_session__read_header /home/user/linux/tools/perf/util/header.c:3886:2
    torvalds#6 0x8ec714 in perf_session__open /home/user/linux/tools/perf/util/session.c:109:6
    torvalds#7 0x8ebe83 in perf_session__new /home/user/linux/tools/perf/util/session.c:213:10
    torvalds#8 0x60c6de in cmd_script /home/user/linux/tools/perf/builtin-script.c:3856:12
    torvalds#9 0x7b2930 in run_builtin /home/user/linux/tools/perf/perf.c:313:11
    torvalds#10 0x7b120f in handle_internal_command /home/user/linux/tools/perf/perf.c:365:8
    torvalds#11 0x7b2493 in run_argv /home/user/linux/tools/perf/perf.c:409:2
    torvalds#12 0x7b0c89 in main /home/user/linux/tools/perf/perf.c:539:3
    torvalds#13 0x7f5260654b74  (/lib64/libc.so.6+0x27b74)

SUMMARY: AddressSanitizer: 3728 byte(s) leaked in 7 allocation(s).

Signed-off-by: Riccardo Mancini <[email protected]>
Acked-by: Ian Rogers <[email protected]>
Acked-by: Jiri Olsa <[email protected]>
Cc: Adrian Hunter <[email protected]>
Cc: Alexander Shishkin <[email protected]>
Cc: Ian Rogers <[email protected]>
Cc: Kan Liang <[email protected]>
Cc: Leo Yan <[email protected]>
Cc: Mark Rutland <[email protected]>
Cc: Namhyung Kim <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Link: http://lore.kernel.org/lkml/[email protected]
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>
Cc: [email protected] # 5.10.228
Signed-off-by: Shuai Xue <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
mj22226 pushed a commit to mj22226/linux that referenced this pull request Nov 21, 2024
commit 5b188cc upstream.

Disable strict aliasing, as has been done in the kernel proper for decades
(literally since before git history) to fix issues where gcc will optimize
away loads in code that looks 100% correct, but is _technically_ undefined
behavior, and thus can be thrown away by the compiler.

E.g. arm64's vPMU counter access test casts a uint64_t (unsigned long)
pointer to a u64 (unsigned long long) pointer when setting PMCR.N via
u64p_replace_bits(), which gcc-13 detects and optimizes away, i.e. ignores
the result and uses the original PMCR.

The issue is most easily observed by making set_pmcr_n() noinline and
wrapping the call with printf(), e.g. sans comments, for this code:

  printf("orig = %lx, next = %lx, want = %lu\n", pmcr_orig, pmcr, pmcr_n);
  set_pmcr_n(&pmcr, pmcr_n);
  printf("orig = %lx, next = %lx, want = %lu\n", pmcr_orig, pmcr, pmcr_n);

gcc-13 generates:

 0000000000401c90 <set_pmcr_n>:
  401c90:       f9400002        ldr     x2, [x0]
  401c94:       b3751022        bfi     x2, x1, torvalds#11, #5
  401c98:       f9000002        str     x2, [x0]
  401c9c:       d65f03c0        ret

 0000000000402660 <test_create_vpmu_vm_with_pmcr_n>:
  402724:       aa1403e3        mov     x3, x20
  402728:       aa1503e2        mov     x2, x21
  40272c:       aa1603e0        mov     x0, x22
  402730:       aa1503e1        mov     x1, x21
  402734:       940060ff        bl      41ab30 <_IO_printf>
  402738:       aa1403e1        mov     x1, x20
  40273c:       910183e0        add     x0, sp, #0x60
  402740:       97fffd54        bl      401c90 <set_pmcr_n>
  402744:       aa1403e3        mov     x3, x20
  402748:       aa1503e2        mov     x2, x21
  40274c:       aa1503e1        mov     x1, x21
  402750:       aa1603e0        mov     x0, x22
  402754:       940060f7        bl      41ab30 <_IO_printf>

with the value stored in [sp + 0x60] ignored by both printf() above and
in the test proper, resulting in a false failure due to vcpu_set_reg()
simply storing the original value, not the intended value.

  $ ./vpmu_counter_access
  Random seed: 0x6b8b4567
  orig = 3040, next = 3040, want = 0
  orig = 3040, next = 3040, want = 0
  ==== Test Assertion Failure ====
    aarch64/vpmu_counter_access.c:505: pmcr_n == get_pmcr_n(pmcr)
    pid=71578 tid=71578 errno=9 - Bad file descriptor
       1        0x400673: run_access_test at vpmu_counter_access.c:522
       2         (inlined by) main at vpmu_counter_access.c:643
       3        0x4132d7: __libc_start_call_main at libc-start.o:0
       4        0x413653: __libc_start_main at ??:0
       5        0x40106f: _start at ??:0
    Failed to update PMCR.N to 0 (received: 6)

Somewhat bizarrely, gcc-11 also exhibits the same behavior, but only if
set_pmcr_n() is marked noinline, whereas gcc-13 fails even if set_pmcr_n()
is inlined in its sole caller.

Cc: [email protected]
Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=116912
Signed-off-by: Sean Christopherson <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
Kaz205 pushed a commit to Kaz205/linux that referenced this pull request Nov 22, 2024
commit 5b188cc upstream.

Disable strict aliasing, as has been done in the kernel proper for decades
(literally since before git history) to fix issues where gcc will optimize
away loads in code that looks 100% correct, but is _technically_ undefined
behavior, and thus can be thrown away by the compiler.

E.g. arm64's vPMU counter access test casts a uint64_t (unsigned long)
pointer to a u64 (unsigned long long) pointer when setting PMCR.N via
u64p_replace_bits(), which gcc-13 detects and optimizes away, i.e. ignores
the result and uses the original PMCR.

The issue is most easily observed by making set_pmcr_n() noinline and
wrapping the call with printf(), e.g. sans comments, for this code:

  printf("orig = %lx, next = %lx, want = %lu\n", pmcr_orig, pmcr, pmcr_n);
  set_pmcr_n(&pmcr, pmcr_n);
  printf("orig = %lx, next = %lx, want = %lu\n", pmcr_orig, pmcr, pmcr_n);

gcc-13 generates:

 0000000000401c90 <set_pmcr_n>:
  401c90:       f9400002        ldr     x2, [x0]
  401c94:       b3751022        bfi     x2, x1, torvalds#11, #5
  401c98:       f9000002        str     x2, [x0]
  401c9c:       d65f03c0        ret

 0000000000402660 <test_create_vpmu_vm_with_pmcr_n>:
  402724:       aa1403e3        mov     x3, x20
  402728:       aa1503e2        mov     x2, x21
  40272c:       aa1603e0        mov     x0, x22
  402730:       aa1503e1        mov     x1, x21
  402734:       940060ff        bl      41ab30 <_IO_printf>
  402738:       aa1403e1        mov     x1, x20
  40273c:       910183e0        add     x0, sp, #0x60
  402740:       97fffd54        bl      401c90 <set_pmcr_n>
  402744:       aa1403e3        mov     x3, x20
  402748:       aa1503e2        mov     x2, x21
  40274c:       aa1503e1        mov     x1, x21
  402750:       aa1603e0        mov     x0, x22
  402754:       940060f7        bl      41ab30 <_IO_printf>

with the value stored in [sp + 0x60] ignored by both printf() above and
in the test proper, resulting in a false failure due to vcpu_set_reg()
simply storing the original value, not the intended value.

  $ ./vpmu_counter_access
  Random seed: 0x6b8b4567
  orig = 3040, next = 3040, want = 0
  orig = 3040, next = 3040, want = 0
  ==== Test Assertion Failure ====
    aarch64/vpmu_counter_access.c:505: pmcr_n == get_pmcr_n(pmcr)
    pid=71578 tid=71578 errno=9 - Bad file descriptor
       1        0x400673: run_access_test at vpmu_counter_access.c:522
       2         (inlined by) main at vpmu_counter_access.c:643
       3        0x4132d7: __libc_start_call_main at libc-start.o:0
       4        0x413653: __libc_start_main at ??:0
       5        0x40106f: _start at ??:0
    Failed to update PMCR.N to 0 (received: 6)

Somewhat bizarrely, gcc-11 also exhibits the same behavior, but only if
set_pmcr_n() is marked noinline, whereas gcc-13 fails even if set_pmcr_n()
is inlined in its sole caller.

Cc: [email protected]
Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=116912
Signed-off-by: Sean Christopherson <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
roxell added a commit to roxell/linux that referenced this pull request Nov 23, 2024
[  123.491737][    T1] Unexpected kernel BRK exception at EL1
[  123.497593][    T1] Internal error: ptrace BRK handler: f20003e8 [#1] PREEMPT SMP
[  123.500785][    T1] Modules linked in:
[  123.502567][    T1] CPU: 0 PID: 1 Comm: swapper/0 Tainted: G        W         5.8.0-rc3-next-20200630-00003-g15e24419c239-dirty torvalds#11
[  123.507468][    T1] Hardware name: linux,dummy-virt (DT)
[  123.509826][    T1] pstate: 80400005 (Nzcv daif +PAN -UAO BTYPE=--)
[  123.512609][    T1] pc : of_unittest_untrack_overlay+0x64/0x134
[  123.515245][    T1] lr : of_unittest_untrack_overlay+0x64/0x134
[  123.517848][    T1] sp : ffff00006a65fb30
[  123.519668][    T1] x29: ffff00006a65fb30 x28: 0000000000000000
[  123.522295][    T1] x27: ffff00006a65fc30 x26: ffffa00016b86f00
[  123.524937][    T1] x25: 0000000000000000 x24: 0000000000000000
[  123.527592][    T1] x23: ffffa00014c72540 x22: ffffa00016b86000
[  123.530191][    T1] x21: 0000000000000000 x20: 00000000ffffffff
[  123.532845][    T1] x19: 00000000ffffffff x18: 0000000000002690
[  123.535547][    T1] x17: 0000000000002718 x16: 00000000000014b8
[  123.538299][    T1] x15: 0000000000000001 x14: 0080000000000000
[  123.541055][    T1] x13: 0000000000000002 x12: ffff94000298d209
[  123.543801][    T1] x11: 1ffff4000298d208 x10: ffff94000298d208
[  123.546580][    T1] x9 : dfffa00000000000 x8 : ffffa00014c69047
[  123.549247][    T1] x7 : 0000000000000001 x6 : ffffa00014c69040
[  123.552026][    T1] x5 : ffff00006a654040 x4 : 0000000000000000
[  123.554799][    T1] x3 : ffffa00011d59d04 x2 : 00000000ffffffff
[  123.557541][    T1] x1 : ffff00006a654040 x0 : 0000000000000000
[  123.560390][    T1] Call trace:
[  123.561935][    T1]  of_unittest_untrack_overlay+0x64/0x134
[  123.564469][    T1]  of_unittest+0x2220/0x2438
[  123.566585][    T1]  do_one_initcall+0x470/0xa10
[  123.568751][    T1]  kernel_init_freeable+0x510/0x5f0
[  123.571123][    T1]  kernel_init+0x18/0x1e8
[  123.573078][    T1]  ret_from_fork+0x10/0x18
[  123.575119][    T1] Code: 97978a9c d4210000 14000024 97978a99 (d4207d00)
[  123.578138][    T1] ---[ end trace c4e049fb5e3b0ba0 ]---
[  123.580449][    T1] Kernel panic - not syncing: Fatal exception
[  123.583116][    T1] Kernel Offset: disabled
[  123.585066][    T1] CPU features: 0x240002,20002004
[  123.587259][    T1] Memory Limit: none
[  123.588986][    T1] ---[ end Kernel panic - not syncing: Fatal exception ]---

Signed-off-by: Anders Roxell <[email protected]>
roxell added a commit to roxell/linux that referenced this pull request Nov 25, 2024
[  123.491737][    T1] Unexpected kernel BRK exception at EL1
[  123.497593][    T1] Internal error: ptrace BRK handler: f20003e8 [#1] PREEMPT SMP
[  123.500785][    T1] Modules linked in:
[  123.502567][    T1] CPU: 0 PID: 1 Comm: swapper/0 Tainted: G        W         5.8.0-rc3-next-20200630-00003-g15e24419c239-dirty torvalds#11
[  123.507468][    T1] Hardware name: linux,dummy-virt (DT)
[  123.509826][    T1] pstate: 80400005 (Nzcv daif +PAN -UAO BTYPE=--)
[  123.512609][    T1] pc : of_unittest_untrack_overlay+0x64/0x134
[  123.515245][    T1] lr : of_unittest_untrack_overlay+0x64/0x134
[  123.517848][    T1] sp : ffff00006a65fb30
[  123.519668][    T1] x29: ffff00006a65fb30 x28: 0000000000000000
[  123.522295][    T1] x27: ffff00006a65fc30 x26: ffffa00016b86f00
[  123.524937][    T1] x25: 0000000000000000 x24: 0000000000000000
[  123.527592][    T1] x23: ffffa00014c72540 x22: ffffa00016b86000
[  123.530191][    T1] x21: 0000000000000000 x20: 00000000ffffffff
[  123.532845][    T1] x19: 00000000ffffffff x18: 0000000000002690
[  123.535547][    T1] x17: 0000000000002718 x16: 00000000000014b8
[  123.538299][    T1] x15: 0000000000000001 x14: 0080000000000000
[  123.541055][    T1] x13: 0000000000000002 x12: ffff94000298d209
[  123.543801][    T1] x11: 1ffff4000298d208 x10: ffff94000298d208
[  123.546580][    T1] x9 : dfffa00000000000 x8 : ffffa00014c69047
[  123.549247][    T1] x7 : 0000000000000001 x6 : ffffa00014c69040
[  123.552026][    T1] x5 : ffff00006a654040 x4 : 0000000000000000
[  123.554799][    T1] x3 : ffffa00011d59d04 x2 : 00000000ffffffff
[  123.557541][    T1] x1 : ffff00006a654040 x0 : 0000000000000000
[  123.560390][    T1] Call trace:
[  123.561935][    T1]  of_unittest_untrack_overlay+0x64/0x134
[  123.564469][    T1]  of_unittest+0x2220/0x2438
[  123.566585][    T1]  do_one_initcall+0x470/0xa10
[  123.568751][    T1]  kernel_init_freeable+0x510/0x5f0
[  123.571123][    T1]  kernel_init+0x18/0x1e8
[  123.573078][    T1]  ret_from_fork+0x10/0x18
[  123.575119][    T1] Code: 97978a9c d4210000 14000024 97978a99 (d4207d00)
[  123.578138][    T1] ---[ end trace c4e049fb5e3b0ba0 ]---
[  123.580449][    T1] Kernel panic - not syncing: Fatal exception
[  123.583116][    T1] Kernel Offset: disabled
[  123.585066][    T1] CPU features: 0x240002,20002004
[  123.587259][    T1] Memory Limit: none
[  123.588986][    T1] ---[ end Kernel panic - not syncing: Fatal exception ]---

Signed-off-by: Anders Roxell <[email protected]>
roxell added a commit to roxell/linux that referenced this pull request Nov 26, 2024
[  123.491737][    T1] Unexpected kernel BRK exception at EL1
[  123.497593][    T1] Internal error: ptrace BRK handler: f20003e8 [#1] PREEMPT SMP
[  123.500785][    T1] Modules linked in:
[  123.502567][    T1] CPU: 0 PID: 1 Comm: swapper/0 Tainted: G        W         5.8.0-rc3-next-20200630-00003-g15e24419c239-dirty torvalds#11
[  123.507468][    T1] Hardware name: linux,dummy-virt (DT)
[  123.509826][    T1] pstate: 80400005 (Nzcv daif +PAN -UAO BTYPE=--)
[  123.512609][    T1] pc : of_unittest_untrack_overlay+0x64/0x134
[  123.515245][    T1] lr : of_unittest_untrack_overlay+0x64/0x134
[  123.517848][    T1] sp : ffff00006a65fb30
[  123.519668][    T1] x29: ffff00006a65fb30 x28: 0000000000000000
[  123.522295][    T1] x27: ffff00006a65fc30 x26: ffffa00016b86f00
[  123.524937][    T1] x25: 0000000000000000 x24: 0000000000000000
[  123.527592][    T1] x23: ffffa00014c72540 x22: ffffa00016b86000
[  123.530191][    T1] x21: 0000000000000000 x20: 00000000ffffffff
[  123.532845][    T1] x19: 00000000ffffffff x18: 0000000000002690
[  123.535547][    T1] x17: 0000000000002718 x16: 00000000000014b8
[  123.538299][    T1] x15: 0000000000000001 x14: 0080000000000000
[  123.541055][    T1] x13: 0000000000000002 x12: ffff94000298d209
[  123.543801][    T1] x11: 1ffff4000298d208 x10: ffff94000298d208
[  123.546580][    T1] x9 : dfffa00000000000 x8 : ffffa00014c69047
[  123.549247][    T1] x7 : 0000000000000001 x6 : ffffa00014c69040
[  123.552026][    T1] x5 : ffff00006a654040 x4 : 0000000000000000
[  123.554799][    T1] x3 : ffffa00011d59d04 x2 : 00000000ffffffff
[  123.557541][    T1] x1 : ffff00006a654040 x0 : 0000000000000000
[  123.560390][    T1] Call trace:
[  123.561935][    T1]  of_unittest_untrack_overlay+0x64/0x134
[  123.564469][    T1]  of_unittest+0x2220/0x2438
[  123.566585][    T1]  do_one_initcall+0x470/0xa10
[  123.568751][    T1]  kernel_init_freeable+0x510/0x5f0
[  123.571123][    T1]  kernel_init+0x18/0x1e8
[  123.573078][    T1]  ret_from_fork+0x10/0x18
[  123.575119][    T1] Code: 97978a9c d4210000 14000024 97978a99 (d4207d00)
[  123.578138][    T1] ---[ end trace c4e049fb5e3b0ba0 ]---
[  123.580449][    T1] Kernel panic - not syncing: Fatal exception
[  123.583116][    T1] Kernel Offset: disabled
[  123.585066][    T1] CPU features: 0x240002,20002004
[  123.587259][    T1] Memory Limit: none
[  123.588986][    T1] ---[ end Kernel panic - not syncing: Fatal exception ]---

Signed-off-by: Anders Roxell <[email protected]>
sean-jc added a commit to sean-jc/linux that referenced this pull request Nov 27, 2024
Disable strict aliasing, as has been done in the kernel proper for decades
(literally since before git history) to fix issues where gcc will optimize
away loads in code that looks 100% correct, but is _technically_ undefined
behavior, and thus can be thrown away by the compiler.

E.g. arm64's vPMU counter access test casts a uint64_t (unsigned long)
pointer to a u64 (unsigned long long) pointer when setting PMCR.N via
u64p_replace_bits(), which gcc-13 detects and optimizes away, i.e. ignores
the result and uses the original PMCR.

The issue is most easily observed by making set_pmcr_n() noinline and
wrapping the call with printf(), e.g. sans comments, for this code:

  printf("orig = %lx, next = %lx, want = %lu\n", pmcr_orig, pmcr, pmcr_n);
  set_pmcr_n(&pmcr, pmcr_n);
  printf("orig = %lx, next = %lx, want = %lu\n", pmcr_orig, pmcr, pmcr_n);

gcc-13 generates:

 0000000000401c90 <set_pmcr_n>:
  401c90:       f9400002        ldr     x2, [x0]
  401c94:       b3751022        bfi     x2, x1, torvalds#11, #5
  401c98:       f9000002        str     x2, [x0]
  401c9c:       d65f03c0        ret

 0000000000402660 <test_create_vpmu_vm_with_pmcr_n>:
  402724:       aa1403e3        mov     x3, x20
  402728:       aa1503e2        mov     x2, x21
  40272c:       aa1603e0        mov     x0, x22
  402730:       aa1503e1        mov     x1, x21
  402734:       940060ff        bl      41ab30 <_IO_printf>
  402738:       aa1403e1        mov     x1, x20
  40273c:       910183e0        add     x0, sp, #0x60
  402740:       97fffd54        bl      401c90 <set_pmcr_n>
  402744:       aa1403e3        mov     x3, x20
  402748:       aa1503e2        mov     x2, x21
  40274c:       aa1503e1        mov     x1, x21
  402750:       aa1603e0        mov     x0, x22
  402754:       940060f7        bl      41ab30 <_IO_printf>

with the value stored in [sp + 0x60] ignored by both printf() above and
in the test proper, resulting in a false failure due to vcpu_set_reg()
simply storing the original value, not the intended value.

  $ ./vpmu_counter_access
  Random seed: 0x6b8b4567
  orig = 3040, next = 3040, want = 0
  orig = 3040, next = 3040, want = 0
  ==== Test Assertion Failure ====
    aarch64/vpmu_counter_access.c:505: pmcr_n == get_pmcr_n(pmcr)
    pid=71578 tid=71578 errno=9 - Bad file descriptor
       1        0x400673: run_access_test at vpmu_counter_access.c:522
       2         (inlined by) main at vpmu_counter_access.c:643
       3        0x4132d7: __libc_start_call_main at libc-start.o:0
       4        0x413653: __libc_start_main at ??:0
       5        0x40106f: _start at ??:0
    Failed to update PMCR.N to 0 (received: 6)

Somewhat bizarrely, gcc-11 also exhibits the same behavior, but only if
set_pmcr_n() is marked noinline, whereas gcc-13 fails even if set_pmcr_n()
is inlined in its sole caller.

Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=116912
Signed-off-by: Sean Christopherson <[email protected]>
roxell added a commit to roxell/linux that referenced this pull request Nov 28, 2024
[  123.491737][    T1] Unexpected kernel BRK exception at EL1
[  123.497593][    T1] Internal error: ptrace BRK handler: f20003e8 [#1] PREEMPT SMP
[  123.500785][    T1] Modules linked in:
[  123.502567][    T1] CPU: 0 PID: 1 Comm: swapper/0 Tainted: G        W         5.8.0-rc3-next-20200630-00003-g15e24419c239-dirty torvalds#11
[  123.507468][    T1] Hardware name: linux,dummy-virt (DT)
[  123.509826][    T1] pstate: 80400005 (Nzcv daif +PAN -UAO BTYPE=--)
[  123.512609][    T1] pc : of_unittest_untrack_overlay+0x64/0x134
[  123.515245][    T1] lr : of_unittest_untrack_overlay+0x64/0x134
[  123.517848][    T1] sp : ffff00006a65fb30
[  123.519668][    T1] x29: ffff00006a65fb30 x28: 0000000000000000
[  123.522295][    T1] x27: ffff00006a65fc30 x26: ffffa00016b86f00
[  123.524937][    T1] x25: 0000000000000000 x24: 0000000000000000
[  123.527592][    T1] x23: ffffa00014c72540 x22: ffffa00016b86000
[  123.530191][    T1] x21: 0000000000000000 x20: 00000000ffffffff
[  123.532845][    T1] x19: 00000000ffffffff x18: 0000000000002690
[  123.535547][    T1] x17: 0000000000002718 x16: 00000000000014b8
[  123.538299][    T1] x15: 0000000000000001 x14: 0080000000000000
[  123.541055][    T1] x13: 0000000000000002 x12: ffff94000298d209
[  123.543801][    T1] x11: 1ffff4000298d208 x10: ffff94000298d208
[  123.546580][    T1] x9 : dfffa00000000000 x8 : ffffa00014c69047
[  123.549247][    T1] x7 : 0000000000000001 x6 : ffffa00014c69040
[  123.552026][    T1] x5 : ffff00006a654040 x4 : 0000000000000000
[  123.554799][    T1] x3 : ffffa00011d59d04 x2 : 00000000ffffffff
[  123.557541][    T1] x1 : ffff00006a654040 x0 : 0000000000000000
[  123.560390][    T1] Call trace:
[  123.561935][    T1]  of_unittest_untrack_overlay+0x64/0x134
[  123.564469][    T1]  of_unittest+0x2220/0x2438
[  123.566585][    T1]  do_one_initcall+0x470/0xa10
[  123.568751][    T1]  kernel_init_freeable+0x510/0x5f0
[  123.571123][    T1]  kernel_init+0x18/0x1e8
[  123.573078][    T1]  ret_from_fork+0x10/0x18
[  123.575119][    T1] Code: 97978a9c d4210000 14000024 97978a99 (d4207d00)
[  123.578138][    T1] ---[ end trace c4e049fb5e3b0ba0 ]---
[  123.580449][    T1] Kernel panic - not syncing: Fatal exception
[  123.583116][    T1] Kernel Offset: disabled
[  123.585066][    T1] CPU features: 0x240002,20002004
[  123.587259][    T1] Memory Limit: none
[  123.588986][    T1] ---[ end Kernel panic - not syncing: Fatal exception ]---

Signed-off-by: Anders Roxell <[email protected]>
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7 participants