diff options
Diffstat (limited to 'src/runtime/mbitmap.go')
| -rw-r--r-- | src/runtime/mbitmap.go | 9 |
1 files changed, 7 insertions, 2 deletions
diff --git a/src/runtime/mbitmap.go b/src/runtime/mbitmap.go index a1d5d8fc81..c97bf0a450 100644 --- a/src/runtime/mbitmap.go +++ b/src/runtime/mbitmap.go @@ -118,15 +118,20 @@ func subtract1(p *byte) *byte { // mHeap_MapBits is called each time arena_used is extended. // It maps any additional bitmap memory needed for the new arena memory. +// It must be called with the expected new value of arena_used, +// *before* h.arena_used has been updated. +// Waiting to update arena_used until after the memory has been mapped +// avoids faults when other threads try access the bitmap immediately +// after observing the change to arena_used. // //go:nowritebarrier -func mHeap_MapBits(h *mheap) { +func mHeap_MapBits(h *mheap, arena_used uintptr) { // Caller has added extra mappings to the arena. // Add extra mappings of bitmap words as needed. // We allocate extra bitmap pieces in chunks of bitmapChunk. const bitmapChunk = 8192 - n := (mheap_.arena_used - mheap_.arena_start) / heapBitmapScale + n := (arena_used - mheap_.arena_start) / heapBitmapScale n = round(n, bitmapChunk) n = round(n, _PhysPageSize) if h.bitmap_mapped >= n { |