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| author | Simon Marlow <marlowsd@gmail.com> | 2013-02-19 09:58:31 +0000 |
|---|---|---|
| committer | Simon Marlow <marlowsd@gmail.com> | 2013-02-19 15:55:22 +0000 |
| commit | a5879a6c2412452fbda8c96e9d921c35279b9d9d (patch) | |
| tree | 0009b9435fb8685b0e016c11de90c07224aad4c8 /rts/sm/Evac.c | |
| parent | 99c80a09f4f0a583545134a098887ef6d194d1ab (diff) | |
| download | haskell-a5879a6c2412452fbda8c96e9d921c35279b9d9d.tar.gz | |
Fix segfault in retainer profiling when using multiple cores (#5909)
Thanks to @akio on the ticket for the diagnosis and the patch. I
modified the comments a bit.
Diffstat (limited to 'rts/sm/Evac.c')
| -rw-r--r-- | rts/sm/Evac.c | 17 |
1 files changed, 15 insertions, 2 deletions
diff --git a/rts/sm/Evac.c b/rts/sm/Evac.c index 4dfbad7e37..35d849e005 100644 --- a/rts/sm/Evac.c +++ b/rts/sm/Evac.c @@ -35,7 +35,7 @@ StgWord64 whitehole_spin = 0; #define HEAP_ALLOCED_GC(p) HEAP_ALLOCED(p) #endif -#if !defined(PARALLEL_GC) +#if !defined(PARALLEL_GC) || defined(PROFILING) #define copy_tag_nolock(p, info, src, size, stp, tag) \ copy_tag(p, info, src, size, stp, tag) #endif @@ -113,6 +113,17 @@ copy_tag(StgClosure **p, const StgInfoTable *info, const StgInfoTable *new_info; new_info = (const StgInfoTable *)cas((StgPtr)&src->header.info, (W_)info, MK_FORWARDING_PTR(to)); if (new_info != info) { +#ifdef PROFILING + // We copied this object at the same time as another + // thread. We'll evacuate the object again and the copy + // we just made will be discarded at the next GC, but we + // may have copied it after the other thread called + // SET_EVACUAEE_FOR_LDV(), which would confuse the LDV + // profiler when it encounters this closure in + // processHeapClosureForDead. So we reset the LDVW field + // here. + LDVW(to) = 0; +#endif return evacuate(p); // does the failed_to_evac stuff } else { *p = TAG_CLOSURE(tag,(StgClosure*)to); @@ -126,11 +137,13 @@ copy_tag(StgClosure **p, const StgInfoTable *info, #ifdef PROFILING // We store the size of the just evacuated object in the LDV word so that // the profiler can guess the position of the next object later. + // This is safe only if we are sure that no other thread evacuates + // the object again, so we cannot use copy_tag_nolock when PROFILING. SET_EVACUAEE_FOR_LDV(from, size); #endif } -#if defined(PARALLEL_GC) +#if defined(PARALLEL_GC) && !defined(PROFILING) STATIC_INLINE void copy_tag_nolock(StgClosure **p, const StgInfoTable *info, StgClosure *src, nat size, nat gen_no, StgWord tag) |