diff options
| author | Austin Clements <austin@google.com> | 2016-10-18 17:29:37 -0400 |
|---|---|---|
| committer | Austin Clements <austin@google.com> | 2016-10-28 18:20:13 +0000 |
| commit | f4dcc9b29b052b99b97d0e445cda589f08bfc798 (patch) | |
| tree | 1972b14266d11a91ed468880efb7a41ca84aac9f /src/runtime | |
| parent | aa581f51570b1c35dc2648226fd8de861de526d4 (diff) | |
| download | go-f4dcc9b29b052b99b97d0e445cda589f08bfc798.tar.xz | |
runtime: make _MSpanDead be the zero state
Currently the zero value of an mspan is in the "in use" state. This
seems like a bad idea in general. But it's going to wreak havoc when
we make fixalloc zero allocations: even "freed" mspan objects are
still on the allspans list and still get looked at by the garbage
collector. Hence, if we leave the mspan states the way they are,
allocating a span that reuses old memory will temporarily pass that
span (which is visible to GC!) through the "in use" state, which can
cause "unswept span" panics.
Fix all of this by making the zero state "dead".
Updates #17503.
Change-Id: I77c7ac06e297af4b9e6258bc091c37abe102acc3
Reviewed-on: https://go-review.googlesource.com/31367
Reviewed-by: Keith Randall <khr@golang.org>
Reviewed-by: Rick Hudson <rlh@golang.org>
Diffstat (limited to 'src/runtime')
| -rw-r--r-- | src/runtime/mheap.go | 8 |
1 files changed, 4 insertions, 4 deletions
diff --git a/src/runtime/mheap.go b/src/runtime/mheap.go index 9c691c6887..d17363261e 100644 --- a/src/runtime/mheap.go +++ b/src/runtime/mheap.go @@ -141,19 +141,19 @@ var mheap_ mheap type mSpanState uint8 const ( - _MSpanInUse mSpanState = iota // allocated for garbage collected heap - _MSpanStack // allocated for use by stack allocator + _MSpanDead mSpanState = iota + _MSpanInUse // allocated for garbage collected heap + _MSpanStack // allocated for use by stack allocator _MSpanFree - _MSpanDead ) // mSpanStateNames are the names of the span states, indexed by // mSpanState. var mSpanStateNames = []string{ + "_MSpanDead", "_MSpanInUse", "_MSpanStack", "_MSpanFree", - "_MSpanDead", } // mSpanList heads a linked list of spans. |