diff options
Diffstat (limited to 'src/runtime')
| -rw-r--r-- | src/runtime/preempt.go | 1 | ||||
| -rw-r--r-- | src/runtime/runtime2.go | 39 | ||||
| -rw-r--r-- | src/runtime/stack.go | 23 |
3 files changed, 47 insertions, 16 deletions
diff --git a/src/runtime/preempt.go b/src/runtime/preempt.go index c41c355835..364929f635 100644 --- a/src/runtime/preempt.go +++ b/src/runtime/preempt.go @@ -173,6 +173,7 @@ func suspendG(gp *g) suspendGState { // _Gscan bit and thus own the stack. gp.preemptStop = false gp.preempt = false + gp.preemptRecent = true gp.stackguard0 = gp.stack.lo + stackGuard // The goroutine was already at a safe-point diff --git a/src/runtime/runtime2.go b/src/runtime/runtime2.go index 05cf345baf..f42c940b8e 100644 --- a/src/runtime/runtime2.go +++ b/src/runtime/runtime2.go @@ -466,22 +466,29 @@ type g struct { runnableTime int64 // the amount of time spent runnable, cleared when running, only used when tracking lockedm muintptr fipsIndicator uint8 - sig uint32 - writebuf []byte - sigcode0 uintptr - sigcode1 uintptr - sigpc uintptr - parentGoid uint64 // goid of goroutine that created this goroutine - gopc uintptr // pc of go statement that created this goroutine - ancestors *[]ancestorInfo // ancestor information goroutine(s) that created this goroutine (only used if debug.tracebackancestors) - startpc uintptr // pc of goroutine function - racectx uintptr - waiting *sudog // sudog structures this g is waiting on (that have a valid elem ptr); in lock order - cgoCtxt []uintptr // cgo traceback context - labels unsafe.Pointer // profiler labels - timer *timer // cached timer for time.Sleep - sleepWhen int64 // when to sleep until - selectDone atomic.Uint32 // are we participating in a select and did someone win the race? + + // preemptRecent is set when a goroutine is preempted. It is + // reset by code passing through the synchronous preemption + // path. It is used to avoid growing the stack when we were + // just preempting, see issue 35470. + preemptRecent bool + + sig uint32 + writebuf []byte + sigcode0 uintptr + sigcode1 uintptr + sigpc uintptr + parentGoid uint64 // goid of goroutine that created this goroutine + gopc uintptr // pc of go statement that created this goroutine + ancestors *[]ancestorInfo // ancestor information goroutine(s) that created this goroutine (only used if debug.tracebackancestors) + startpc uintptr // pc of goroutine function + racectx uintptr + waiting *sudog // sudog structures this g is waiting on (that have a valid elem ptr); in lock order + cgoCtxt []uintptr // cgo traceback context + labels unsafe.Pointer // profiler labels + timer *timer // cached timer for time.Sleep + sleepWhen int64 // when to sleep until + selectDone atomic.Uint32 // are we participating in a select and did someone win the race? // goroutineProfiled indicates the status of this goroutine's stack for the // current in-progress goroutine profile diff --git a/src/runtime/stack.go b/src/runtime/stack.go index 2fedaa9421..67a394cd12 100644 --- a/src/runtime/stack.go +++ b/src/runtime/stack.go @@ -1075,6 +1075,29 @@ func newstack() { gopreempt_m(gp) // never return } + if stackguard0 == gp.stack.lo+stackGuard && gp.preemptRecent { + // The case happens because of an interaction between synchronous + // and asynchronous preemption. First, we set the cooperative + // preemption signal (g.stackguard0 = stackPreempt), and as a + // result the function fails the stack check and enters its + // morestack path. If it gets suspended at that point, we might + // give up waiting for it and send an async preempt. That async + // preempt gets processed and clears the cooperative preemption + // signal (g.stackguard0 = g.stack.lo+stackGuard) and resumes + // the function. But even though the cooperative preemption + // signal is cleared, we're already on the morestack path and + // can't avoid calling morestack. See issue 35470. + // + // To avoid this problem, if we've been preempted recently, + // clear the "preempted recently" flag and resume the G. + // If we really did need more stack, the morestack check will + // immediately fail and we'll get back here to try again (with + // preemptRecent==false, so we don't take this case the + // second time). + gp.preemptRecent = false + gogo(&gp.sched) // never return + } + // Allocate a bigger segment and move the stack. oldsize := gp.stack.hi - gp.stack.lo newsize := oldsize * 2 |