| commit | 7ed7669c0d35768dbb73eb33d7dc0098e45421b1 | [log] [tgz] |
|---|---|---|
| author | Michael Anthony Knyszek <mknyszek@google.com> | Fri May 17 14:48:04 2019 +0000 |
| committer | Michael Knyszek <mknyszek@google.com> | Fri May 24 15:34:57 2019 +0000 |
| tree | 33210a5887e63784342843d563c604e3dbce1216 | |
| parent | db3255536cdbdba9d6f38da9c3bb1faf55f63277 [diff] |
runtime: ensure mheap lock stack growth invariant is maintained
Currently there's an invariant in the runtime wherein the heap lock
can only be acquired on the system stack, otherwise a self-deadlock
could occur if the stack grows while the lock is held.
This invariant is upheld and documented in a number of situations (e.g.
allocManual, freeManual) but there are other places where the invariant
is either not maintained at all which risks self-deadlock (e.g.
setGCPercent, gcResetMarkState, allocmcache) or is maintained but
undocumented (e.g. gcSweep, readGCStats_m).
This change adds go:systemstack to any function that acquires the heap
lock or adds a systemstack(func() { ... }) around the critical section,
where appropriate. It also documents the invariant on (*mheap).lock
directly and updates repetitive documentation to refer to that comment.
Fixes #32105.
Change-Id: I702b1290709c118b837389c78efde25c51a2cafb
Reviewed-on: https://go-review.googlesource.com/c/go/+/177857
Run-TryBot: Michael Knyszek <mknyszek@google.com>
Reviewed-by: Austin Clements <austin@google.com>
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