Fuchsia + lld page-faulting on FnOnce::call_once vtable shim

[cramertj]

After the switch to lld, even a minimal Fuchsia binary page-faults at runtime. The backtraces point to the FnOnce::call_once vtable shim added in #54183. I'm not making use of Box<dyn FnOnce> anywhere in Fuchsia directly, but it's possible an std use has snuck in (edit: but it definitely shouldn't be the first function run by the loader?). cc @petrhosek

[00028.682] 09877.09884> PageFault: 473109 free pages
[00028.682] 09877.09884> PageFault: MemoryUsed: proc  1129   10M 'fshost'
[00028.683] 09877.09884> PageFault: MemoryUsed: proc  2945   72M 'blobfs:/blob'
[00028.683] 09877.09884> PageFault: MemoryUsed: proc  3378    8M 'minfs:/data'
[00028.684] 01045.01271> devmgr: crash_analyzer_listener: analyzing exception type 0x108
[00028.684] 01105.01119> <== fatal exception: process ./connectivity_testing_lib_test[9877] thread initial-thread[9884]
[00028.684] 01105.01119> <== fatal page fault, PC at 0x1728953ca000
[00028.684] 01105.01119>  CS:                   0 RIP:     0x1728953ca000 EFL:            0x10202 CR2:         0x4c74dfa5
[00028.684] 01105.01119>  RAX:                  0 RBX:                  0 RCX:                  0 RDX:                  0
[00028.684] 01105.01119>  RSI:     0x79f30ec5a000 RDI:         0x4c74dfa5 RBP:                  0 RSP:      0x1e00e749ff8
[00028.684] 01105.01119>   R8:                  0  R9:                  0 R10:                  0 R11:                  0
[00028.684] 01105.01119>  R12:                  0 R13:                  0 R14:                  0 R15:                  0
[00028.684] 01105.01119>  errc:               0x4
[00028.684] 01105.01119> bottom of user stack:
[00028.684] 01105.01119> 0x000001e00e749ff8: 00000000 00000000                   |................|
[00028.684] 01105.01119> arch: x86_64
[00028.684] 01105.01119> read_mem @0x8 FAILED 8
[00028.684] 01105.01119> {{{reset}}}
[00028.684] 01105.01119> {{{module:0x1e8931d8:<VMO#9844=connectivity_testing_:elf:30922f7ca740fd8a}}}
[00028.684] 01105.01119> {{{mmap:0x1728953a8000:0x22000:load:0x1e8931d8:r:0}}}
[00028.684] 01105.01119> {{{mmap:0x1728953ca000:0x1000:load:0x1e8931d8:rx:0x22000}}}
[00028.684] 01105.01119> {{{mmap:0x1728953cb000:0x2000:load:0x1e8931d8:rw:0x23000}}}
[00028.684] 01105.01119> {{{module:0x1e8931d9:<VMO#1033=vdso/full>:elf:329e77f0c225f0f29e7d914d7bf2c55f89f90f43}}}
[00028.684] 01105.01119> {{{mmap:0x79f30ec[28.682] 09877.09884> 5a000:0x6000:load:0x1e8931d9:r:0}}}
[00028.684] 01105.01119> {{{mmap:0x79f30ec60000:0x1000:load:0x1e8931d9:rx:0x6000}}}
[00028.684] 01105.01119> bt#01: pc 0x1728953ca000 sp 0x1e00e749fPageFault: 473109 free pagesf8
[00028.684] 01105.01119> bt#02: end
[00028.684] 01105.01119>
 {{{bt:1:0x1728953ca000}}}
[28.682] 09877.09884> PageFault: MemoryUsed: proc  1129   10M 'fshost'
[28.683] 09877.09884> PageFault: MemoryUsed: proc  2945   72M 'blobfs:/blob'
[28.683] 09877.09884> PageFault: MemoryUsed: proc  3378    8M 'minfs:/data'
[28.684] 01045.01271> devmgr: crash_analyzer_listener: analyzing exception type 0x108
[28.684] 01105.01119> <== fatal exception: process ./connectivity_testing_lib_test[9877] thread initial-thread[9884]
[28.684] 01105.01119> <== fatal page fault, PC at 0x1728953ca000
[28.684] 01105.01119> CS:                   0 RIP:     0x1728953ca000 EFL:            0x10202 CR2:         0x4c74dfa5
[28.684] 01105.01119> RAX:                  0 RBX:                  0 RCX:                  0 RDX:                  0
[28.684] 01105.01119> RSI:     0x79f30ec5a000 RDI:         0x4c74dfa5 RBP:                  0 RSP:      0x1e00e749ff8
[28.684] 01105.01119> R8:                  0  R9:                  0 R10:                  0 R11:                  0
[28.684] 01105.01119> R12:                  0 R13:                  0 R14:                  0 R15:                  0
[28.684] 01105.01119> errc:               0x4
[28.684] 01105.01119> bottom of user stack:
[28.684] 01105.01119> 0x000001e00e749ff8: 00000000 00000000                   |................|
[28.684] 01105.01119> arch: x86_64
[28.684] 01105.01119> read_mem @0x8 FAILED 8
[28.684] 01105.01119> bt#01: pc 0x1728953ca000 sp 0x1e00e749ff8
[28.684] 01105.01119> bt#02: end
[28.684] 01105.01119>    #1    0x00001728953ca000 in core::ops::function::FnOnce::call_once::_$u7b$$u7b$vtable.shim$u7d$$u7d$::h10568ef9220c4b73 /b/s/w/ir/kitchen-workdir/rust/src/libcore/ops/function.rs:238 <<VMO#9844=connectivity_testing_>+0x22000

[workingjubilee]

Checking in: Is this still an issue in 2022?

[petrhosek]

I don't think so, it should be safe to close this.