Segmentation fault when yk_mt_control_point commented out
#31
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Looking at this issue I can see that two loops has been detected and locations are set here for instructions: yklocs[29] and yklocs[845] We suspect that this behaviour is caused by GC freeing the |
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And just to be clear we believe this has nothing to do with yk, per se: it's just that we haven't found quite the right places in (yk)lua to alter? |
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This is subtly different, but related to this PR. The crash we saw this morning Pavel, was with the control point uncommented. But I bet the issue of freeing with the control point commented is related to GC too... |
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If the code crashes with the control point commented out, we'd also expect/hope it to crash in the same way with the control point not commented out. [Or, in other words, I believe this issue is orthogonal to the control point.] |
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Yes, either way ( |
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Aug 25, 2023
64: Track initialised yk locations r=ltratt a=Pavel-Durov Partially fixes (only for serial compilation) - #62 # Changes - Remove reallocarray in favour of calloc - Change YkLocations to be stored as pointers - Change lyk interface to reflect its "hooks" functionality - Move tests to a separate test script and enable serialised all.lua test suite - Added logging in lyk module for ease of debugging - Updated readme `test.sh` was tested for resiliency multiple times: ```shell $ try_repeat -v 100 sh ./test.sh ``` # Issues ## Uninitialised locations memory `reallocarray` does not initialise memory with default zero bytes locations as `calloc`. Moving to `calloc` and using pointers allowed to check for NULL with default values set at initialisation time. ## Tests When lua tests are executed one by one as single files it produces different results from when it's executed via `all.lua` test suite. Example: ```shell $ YKD_SERIALISE_COMPILATION=1 ../src/lua -e"_U=true" ./main.lua ... ../src/lua: ./main.lua:343: assertion failed! stack traceback: [C]: in function 'assert' ./main.lua:343: in main chunk [C]: in ? ``` When run through `all.lua` it passes: ```shell $ YKD_SERIALISE_COMPILATION=1 ../src/lua -e"_U=true" ./all.lua ... ***** FILE 'main.lua'***** ... ***** FILE 'gc.lua'***** ... ``` Since `all.lua` is what we base the stability of yklua, I think we should include it in the tests as is, currently only serialised compilation works. Running `all.lua` prior to these changes results in error (`main/56c5787799b876f36babbae24e9afc025806b831`): ``` $ YKD_SERIALISE_COMPILATION=1 gdb -ex 'r' -ex 'bt' --args ../src/lua -e"_U=true" ./all.lua ... ***** FILE 'main.lua'***** Program received signal SIGSEGV, Segmentation fault. core::sync::atomic::AtomicUsize::fetch_sub (self=<optimised out>) at /rustc/ef85656a10657ba5e4f7fe2931a4ca6293138d51/library/core/src/sync/atomic.rs:2575 2575 /rustc/ef85656a10657ba5e4f7fe2931a4ca6293138d51/library/core/src/sync/atomic.rs: No such file or directory. #0 core::sync::atomic::AtomicUsize::fetch_sub (self=<optimised out>) at /rustc/ef85656a10657ba5e4f7fe2931a4ca6293138d51/library/core/src/sync/atomic.rs:2575 #1 alloc::sync::{impl#33}::drop<lock_api::mutex::Mutex<parking_lot::raw_mutex::RawMutex, ykrt::location::HotLocation>, alloc::alloc::Global> (self=0x7fffffffb410) at /rustc/ef85656a10657ba5e4f7fe2931a4ca6293138d51/library/alloc/src/sync.rs:2370 #2 0x00007ffff7b0d4ab in core::ptr::drop_in_place<alloc::sync::Arc<lock_api::mutex::Mutex<parking_lot::raw_mutex::RawMutex, ykrt::location::HotLocation>, alloc::alloc::Global>> () at /rustc/ef85656a10657ba5e4f7fe2931a4ca6293138d51/library/core/src/ptr/mod.rs:497 #3 0x00007ffff7b0067e in core::mem::drop<alloc::sync::Arc<lock_api::mutex::Mutex<parking_lot::raw_mutex::RawMutex, ykrt::location::HotLocation>, alloc::alloc::Global>> (_x=...) at /rustc/ef85656a10657ba5e4f7fe2931a4ca6293138d51/library/core/src/mem/mod.rs:987 #4 0x00007ffff7b121f0 in ykrt::location::{impl#1}::drop (self=0x7fffffffb468) at ykrt/src/location.rs:197 #5 0x00007ffff7affa9b in core::ptr::drop_in_place<ykrt::location::Location> () at /rustc/ef85656a10657ba5e4f7fe2931a4ca6293138d51/library/core/src/ptr/mod.rs:497 #6 0x00007ffff7aff6bd in core::mem::drop<ykrt::location::Location> (_x=...) at /rustc/ef85656a10657ba5e4f7fe2931a4ca6293138d51/library/core/src/mem/mod.rs:987 #7 0x00007ffff7b004bd in ykcapi::yk_location_drop (loc=...) at ykcapi/src/lib.rs:90 #8 0x000000000088aa0e in free_loc (f=<optimised out>, i=<optimised out>, idx=<optimised out>) at lyk.c:66 #9 0x000000000088aba5 in yk_free_locactions (f=0x928cc0) at lyk.c:76 --Type <RET> for more, q to quit, c to continue without paging-- #10 0x0000000000807738 in luaF_freeproto (L=0x916e38, f=0x928cc0) at lfunc.c:276 #11 0x0000000000809fde in freeobj (L=0x916e38, o=0x928cc0) at lgc.c:767 #12 0x0000000000817145 in sweepgen (L=0x916e38, g=<optimised out>, p=<optimised out>, limit=<optimised out>, pfirstold1=<optimised out>) at lgc.c:1106 #13 0x0000000000816713 in youngcollection (L=0x916e38, g=0x916f00) at lgc.c:1239 #14 0x000000000081557d in genstep (L=0x916e38, g=0x916f00) at lgc.c:1434 #15 0x0000000000815044 in luaC_step (L=0x916e38) at lgc.c:1686 #16 0x00000000007e4447 in lua_pushstring (L=0x916e38, s=<optimised out>) at lapi.c:553 #17 0x000000000089e60c in findloader (L=0x916e38, name=0x928df8 "tracegc") at loadlib.c:641 #18 0x000000000089de0a in ll_require (L=0x916e38) at loadlib.c:666 #19 0x00000000007fda75 in precallC (L=0x916e38, func=<optimised out>, nresults=<optimised out>, f=0x89db80 <ll_require>) at ldo.c:506 #20 0x00000000007fe016 in luaD_precall (L=0x916e38, func=0x923780, nresults=1) at ldo.c:569 #21 0x0000000000883f68 in luaV_execute (L=0x916e38, ci=<optimised out>) at lvm.c:1655 #22 0x00000000007feb3b in ccall (L=0x916e38, func=<optimised out>, nResults=<optimised out>, inc=<optimised out>) at ldo.c:609 #23 0x00000000007fec61 in luaD_callnoyield (L=0x916e38, func=0x917730, nResults=-1) at ldo.c:627 #24 0x00000000007eaf03 in f_call (L=0x916e38, ud=<optimised out>) at lapi.c:1041 #25 0x00000000007f8be7 in luaD_rawrunprotected (L=0x916e38, f=0x7eae40 <f_call>, ud=0x7ffff2487308) at ldo.c:144 #26 0x0000000000801406 in luaD_pcall (L=0x916e38, func=0x7eae40 <f_call>, u=0x7ffff2487308, old_top=<optimised out>, ef=<optimised out>) at ldo.c:926 #27 0x00000000007ea9ec in lua_pcallk (L=0x916e38, nargs=<optimised out>, nresults=<optimised out>, errfunc=<optimised out>, ctx=<optimised out>, k=<optimised out>) at lapi.c:1067 #28 0x00000000007dc623 in docall (L=0x916e38, narg=0, nres=-1) at lua.c:160 #29 0x00000000007dbd24 in handle_script (L=0x916e38, argv=<optimised out>) at lua.c:255 #30 0x00000000007d9fe3 in pmain (L=0x916e38) at lua.c:634 #31 0x00000000007fda75 in precallC (L=0x916e38, func=<optimised out>, nresults=<optimised out>, f=0x7d97f0 <pmain>) at ldo.c:506 #32 0x00000000007fe0c8 in luaD_precall (L=0x916e38, func=0x9176f0, nresults=1) at ldo.c:572 #33 0x00000000007fea7f in ccall (L=0x916e38, func=0x9176f0, nResults=1, inc=<optimised out>) at ldo.c:607 #34 0x00000000007fec61 in luaD_callnoyield (L=0x916e38, func=0x9176f0, nResults=1) at ldo.c:627 #35 0x00000000007eaf03 in f_call (L=0x916e38, ud=<optimised out>) at lapi.c:1041 #36 0x00000000007f8be7 in luaD_rawrunprotected (L=0x916e38, f=0x7eae40 <f_call>, ud=0x7ffff2487058) at ldo.c:144 #37 0x0000000000801406 in luaD_pcall (L=0x916e38, func=0x7eae40 <f_call>, u=0x7ffff2487058, old_top=<optimised out>, ef=<optimised out>) at ldo.c:926 #38 0x00000000007ea9ec in lua_pcallk (L=0x916e38, nargs=<optimised out>, nresults=<optimised out>, errfunc=<optimised out>, ctx=<optimised out>, k=<optimised out>) at lapi.c:1067 #39 0x00000000007d94b0 in main (argc=<optimised out>, argv=<optimised out>) at lua.c:660 ``` That's cause we're freeing uninitialised yk locations. Co-authored-by: Pavel Durov <[email protected]>
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When I comment out the
yk_mt_control_point:I get a segment fault at
yk_location_drop:Yk commit:
5bcd2c575e0c59ea964e1bf6b11eb4c85142b140The text was updated successfully, but these errors were encountered: