diff --git a/src/runtime/proc.go b/src/runtime/proc.go index ded406cc28..59160c6525 100644 --- a/src/runtime/proc.go +++ b/src/runtime/proc.go @@ -4083,8 +4083,16 @@ func exitsyscall0(gp *g) { if schedEnabled(gp) { _p_ = pidleget() } + var locked bool if _p_ == nil { globrunqput(gp) + + // Below, we stoplockedm if gp is locked. globrunqput releases + // ownership of gp, so we must check if gp is locked prior to + // committing the release by unlocking sched.lock, otherwise we + // could race with another M transitioning gp from unlocked to + // locked. + locked = gp.lockedm != 0 } else if atomic.Load(&sched.sysmonwait) != 0 { atomic.Store(&sched.sysmonwait, 0) notewakeup(&sched.sysmonnote) @@ -4094,7 +4102,7 @@ func exitsyscall0(gp *g) { acquirep(_p_) execute(gp, false) // Never returns. } - if gp.lockedm != 0 { + if locked { // Wait until another thread schedules gp and so m again. // // N.B. lockedm must be this M, as this g was running on this M