diff --git a/src/runtime/mgcwork.go b/src/runtime/mgcwork.go index f2c16d7d8c..927b06c3f9 100644 --- a/src/runtime/mgcwork.go +++ b/src/runtime/mgcwork.go @@ -126,12 +126,12 @@ func (w *gcWork) checkPut(ptr uintptr, ptrs []uintptr) { if debugCachedWork { alreadyFailed := w.putGen == w.pauseGen w.putGen = w.pauseGen - if m := getg().m; m.locks > 0 || m.mallocing != 0 || m.preemptoff != "" || m.p.ptr().status != _Prunning { + if !canPreemptM(getg().m) { // If we were to spin, the runtime may - // deadlock: the condition above prevents - // preemption (see newstack), which could - // prevent gcMarkDone from finishing the - // ragged barrier and releasing the spin. + // deadlock. Since we can't be preempted, the + // spin could prevent gcMarkDone from + // finishing the ragged barrier, which is what + // releases us from the spin. return } for atomic.Load(&gcWorkPauseGen) == w.pauseGen { diff --git a/src/runtime/preempt.go b/src/runtime/preempt.go index 0565fd6360..96eaa3488b 100644 --- a/src/runtime/preempt.go +++ b/src/runtime/preempt.go @@ -223,3 +223,12 @@ func resumeG(state suspendGState) { ready(gp, 0, true) } } + +// canPreemptM reports whether mp is in a state that is safe to preempt. +// +// It is nosplit because it has nosplit callers. +// +//go:nosplit +func canPreemptM(mp *m) bool { + return mp.locks == 0 && mp.mallocing == 0 && mp.preemptoff == "" && mp.p.ptr().status == _Prunning +} diff --git a/src/runtime/proc.go b/src/runtime/proc.go index 9a553a5f88..60a15c1e9c 100644 --- a/src/runtime/proc.go +++ b/src/runtime/proc.go @@ -2703,7 +2703,7 @@ func gosched_m(gp *g) { // goschedguarded is a forbidden-states-avoided version of gosched_m func goschedguarded_m(gp *g) { - if gp.m.locks != 0 || gp.m.mallocing != 0 || gp.m.preemptoff != "" || gp.m.p.ptr().status != _Prunning { + if !canPreemptM(gp.m) { gogo(&gp.sched) // never return } diff --git a/src/runtime/stack.go b/src/runtime/stack.go index 825826cacd..ecefce1e32 100644 --- a/src/runtime/stack.go +++ b/src/runtime/stack.go @@ -975,7 +975,7 @@ func newstack() { // it needs a lock held by the goroutine), that small preemption turns // into a real deadlock. if preempt { - if thisg.m.locks != 0 || thisg.m.mallocing != 0 || thisg.m.preemptoff != "" || thisg.m.p.ptr().status != _Prunning { + if !canPreemptM(thisg.m) { // Let the goroutine keep running for now. // gp->preempt is set, so it will be preempted next time. gp.stackguard0 = gp.stack.lo + _StackGuard