When an M is destroyed, we put its vgetrandom state back on the shared
list for another M to reuse. This list is simply a slice, so appending
to the slice may allocate. Currently this operation is performed in
mdestroy, after the P is released, meaning allocation is not allowed.
More the cleanup earlier in mdestroy when allocation is still OK.
Also add //go:nowritebarrierrec to mdestroy since it runs without a P,
which would have caught this bug.
Fixes #73144.
For #73141.
Change-Id: I6a6a636c3fbf5c6eec09d07a260e39dbb4d2db12
Reviewed-on: https://go-review.googlesource.com/c/go/+/662455
Reviewed-by: Jason Donenfeld <Jason@zx2c4.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Keith Randall <khr@golang.org>
Reviewed-by: Keith Randall <khr@google.com>
(cherry picked from commit
0b31e6d4cc804ab76ae8ced151ee2f50657aec14)
Reviewed-on: https://go-review.googlesource.com/c/go/+/662496
getg().m.procid = 0
}
-// Called from exitm, but not from drop, to undo the effect of thread-owned
+// Called from mexit, but not from dropm, to undo the effect of thread-owned
// resources in minit, semacreate, or elsewhere. Do not take locks after calling this.
+//
+// This always runs without a P, so //go:nowritebarrierrec is required.
+//go:nowritebarrierrec
func mdestroy(mp *m) {
}
getg().m.procid = 0
}
-// Called from exitm, but not from drop, to undo the effect of thread-owned
+// Called from mexit, but not from dropm, to undo the effect of thread-owned
// resources in minit, semacreate, or elsewhere. Do not take locks after calling this.
+//
+// This always runs without a P, so //go:nowritebarrierrec is required.
+//go:nowritebarrierrec
func mdestroy(mp *m) {
}
getg().m.procid = 0
}
-// Called from exitm, but not from drop, to undo the effect of thread-owned
+// Called from mexit, but not from dropm, to undo the effect of thread-owned
// resources in minit, semacreate, or elsewhere. Do not take locks after calling this.
+//
+// This always runs without a P, so //go:nowritebarrierrec is required.
+//go:nowritebarrierrec
func mdestroy(mp *m) {
}
getg().m.procid = 0
}
-// Called from exitm, but not from drop, to undo the effect of thread-owned
+// Called from mexit, but not from dropm, to undo the effect of thread-owned
// resources in minit, semacreate, or elsewhere. Do not take locks after calling this.
+//
+// This always runs without a P, so //go:nowritebarrierrec is required.
+//go:nowritebarrierrec
func mdestroy(mp *m) {
}
getg().m.procid = 0
}
-// Called from exitm, but not from drop, to undo the effect of thread-owned
+// Called from mexit, but not from dropm, to undo the effect of thread-owned
// resources in minit, semacreate, or elsewhere. Do not take locks after calling this.
+//
+// This always runs without a P, so //go:nowritebarrierrec is required.
+//go:nowritebarrierrec
func mdestroy(mp *m) {
- if mp.vgetrandomState != 0 {
- vgetrandomPutState(mp.vgetrandomState)
- mp.vgetrandomState = 0
- }
}
// #ifdef GOARCH_386
// must continue working after unminit.
}
-// Called from exitm, but not from drop, to undo the effect of thread-owned
+// Called from mexit, but not from dropm, to undo the effect of thread-owned
// resources in minit, semacreate, or elsewhere. Do not take locks after calling this.
+//
+// This always runs without a P, so //go:nowritebarrierrec is required.
+//go:nowritebarrierrec
func mdestroy(mp *m) {
}
getg().m.procid = 0
}
-// Called from exitm, but not from drop, to undo the effect of thread-owned
+// Called from mexit, but not from dropm, to undo the effect of thread-owned
// resources in minit, semacreate, or elsewhere. Do not take locks after calling this.
+//
+// This always runs without a P, so //go:nowritebarrierrec is required.
+//go:nowritebarrierrec
func mdestroy(mp *m) {
}
func unminit() {
}
-// Called from exitm, but not from drop, to undo the effect of thread-owned
+// Called from mexit, but not from dropm, to undo the effect of thread-owned
// resources in minit, semacreate, or elsewhere. Do not take locks after calling this.
+//
+// This always runs without a P, so //go:nowritebarrierrec is required.
+//go:nowritebarrierrec
func mdestroy(mp *m) {
}
mp.procid = 0
}
-// Called from exitm, but not from drop, to undo the effect of thread-owned
+// Called from mexit, but not from dropm, to undo the effect of thread-owned
// resources in minit, semacreate, or elsewhere. Do not take locks after calling this.
//
+// This always runs without a P, so //go:nowritebarrierrec is required.
+//go:nowritebarrierrec
//go:nosplit
func mdestroy(mp *m) {
if mp.highResTimer != 0 {
mp.gsignal = nil
}
+ // Free vgetrandom state.
+ vgetrandomDestroy(mp)
+
// Remove m from allm.
lock(&sched.lock)
for pprev := &allm; *pprev != nil; pprev = &(*pprev).alllink {
return state
}
-func vgetrandomPutState(state uintptr) {
+// Free vgetrandom state from the M (if any) prior to destroying the M.
+//
+// This may allocate, so it must have a P.
+func vgetrandomDestroy(mp *m) {
+ if mp.vgetrandomState == 0 {
+ return
+ }
+
lock(&vgetrandomAlloc.statesLock)
- vgetrandomAlloc.states = append(vgetrandomAlloc.states, state)
+ vgetrandomAlloc.states = append(vgetrandomAlloc.states, mp.vgetrandomState)
unlock(&vgetrandomAlloc.statesLock)
}
return -1, false
}
-func vgetrandomPutState(state uintptr) {}
+func vgetrandomDestroy(mp *m) {}
func vgetrandomInit() {}