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mm, THP, swap: fix allocating cluster for swapfile by mistake
BugLink: https://bugs.launchpad.net/bugs/1898076 commit 4166343 upstream. SWP_FS is used to make swap_{read,write}page() go through the filesystem, and it's only used for swap files over NFS. So, !SWP_FS means non NFS for now, it could be either file backed or device backed. Something similar goes with legacy SWP_FILE. So in order to achieve the goal of the original patch, SWP_BLKDEV should be used instead. FS corruption can be observed with SSD device + XFS + fragmented swapfile due to CONFIG_THP_SWAP=y. I reproduced the issue with the following details: Environment: QEMU + upstream kernel + buildroot + NVMe (2 GB) Kernel config: CONFIG_BLK_DEV_NVME=y CONFIG_THP_SWAP=y Some reproducible steps: mkfs.xfs -f /dev/nvme0n1 mkdir /tmp/mnt mount /dev/nvme0n1 /tmp/mnt bs="32k" sz="1024m" # doesn't matter too much, I also tried 16m xfs_io -f -c "pwrite -R -b $bs 0 $sz" -c "fdatasync" /tmp/mnt/sw xfs_io -f -c "pwrite -R -b $bs 0 $sz" -c "fdatasync" /tmp/mnt/sw xfs_io -f -c "pwrite -R -b $bs 0 $sz" -c "fdatasync" /tmp/mnt/sw xfs_io -f -c "pwrite -F -S 0 -b $bs 0 $sz" -c "fdatasync" /tmp/mnt/sw xfs_io -f -c "pwrite -R -b $bs 0 $sz" -c "fsync" /tmp/mnt/sw mkswap /tmp/mnt/sw swapon /tmp/mnt/sw stress --vm 2 --vm-bytes 600M # doesn't matter too much as well Symptoms: - FS corruption (e.g. checksum failure) - memory corruption at: 0xd2808010 - segfault Fixes: f0eea18 ("mm, THP, swap: Don't allocate huge cluster for file backed swap device") Fixes: 38d8b4e ("mm, THP, swap: delay splitting THP during swap out") Signed-off-by: Gao Xiang <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Reviewed-by: "Huang, Ying" <[email protected]> Reviewed-by: Yang Shi <[email protected]> Acked-by: Rafael Aquini <[email protected]> Cc: Matthew Wilcox <[email protected]> Cc: Carlos Maiolino <[email protected]> Cc: Eric Sandeen <[email protected]> Cc: Dave Chinner <[email protected]> Cc: <[email protected]> Link: https://lkml.kernel.org/r/[email protected] Signed-off-by: Linus Torvalds <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> Signed-off-by: Paolo Pisati <[email protected]>
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