diff options
| author | Dmitriy Vyukov <dvyukov@google.com> | 2014-06-28 19:20:46 -0700 |
|---|---|---|
| committer | Dmitriy Vyukov <dvyukov@google.com> | 2014-06-28 19:20:46 -0700 |
| commit | 5bfe8adee5100444cdde78d4897d1673df96c813 (patch) | |
| tree | a699f127993996488d3c1a6906b34d6d736db9a7 /src/pkg/runtime | |
| parent | 94935cb5c1fa5f5e002aa7286f5496a4dad36b5c (diff) | |
| download | go-5bfe8adee5100444cdde78d4897d1673df96c813.tar.xz | |
runtime: fix GC bitmap corruption
Fixes #8299.
R=golang-codereviews
CC=golang-codereviews, khr, rsc
https://golang.org/cl/103640044
Diffstat (limited to 'src/pkg/runtime')
| -rw-r--r-- | src/pkg/runtime/mgc0.c | 15 |
1 files changed, 13 insertions, 2 deletions
diff --git a/src/pkg/runtime/mgc0.c b/src/pkg/runtime/mgc0.c index 3eda4f4b9e..4ad8f3b08f 100644 --- a/src/pkg/runtime/mgc0.c +++ b/src/pkg/runtime/mgc0.c @@ -2731,7 +2731,7 @@ runtime·markscan(void *v) void runtime·markfreed(void *v) { - uintptr *b, off, shift; + uintptr *b, off, shift, xbits; if(0) runtime·printf("markfreed %p\n", v); @@ -2742,7 +2742,18 @@ runtime·markfreed(void *v) off = (uintptr*)v - (uintptr*)runtime·mheap.arena_start; // word offset b = (uintptr*)runtime·mheap.arena_start - off/wordsPerBitmapWord - 1; shift = off % wordsPerBitmapWord; - *b = (*b & ~(bitMask<<shift)) | (bitAllocated<<shift); + if(!g->m->gcing || work.nproc == 1) { + // During normal operation (not GC), the span bitmap is not updated concurrently, + // because either the span is cached or accesses are protected with MCentral lock. + *b = (*b & ~(bitMask<<shift)) | (bitAllocated<<shift); + } else { + // During GC other threads concurrently mark heap. + for(;;) { + xbits = *b; + if(runtime·casp((void**)b, (void*)xbits, (void*)((xbits & ~(bitMask<<shift)) | (bitAllocated<<shift)))) + break; + } + } } // check that the block at v of size n is marked freed. |