From ff2636f45e0087a1c6d8e895257d9c4729710811 Mon Sep 17 00:00:00 2001
From: Michael Pratt <mpratt@google.com>
Date: Thu, 03 Apr 2025 03:26:25 +0000
Subject: [PATCH] [release-branch.go1.24] runtime: cleanup M vgetrandom state before dropping P
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)
---
diff --git a/src/runtime/os3_solaris.go b/src/runtime/os3_solaris.go
index cf163a6..ded821b 100644
--- a/src/runtime/os3_solaris.go
+++ b/src/runtime/os3_solaris.go
@@ -234,8 +234,11 @@
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) {
}
diff --git a/src/runtime/os_aix.go b/src/runtime/os_aix.go
index 93464cb..1b483c2 100644
--- a/src/runtime/os_aix.go
+++ b/src/runtime/os_aix.go
@@ -186,8 +186,11 @@
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) {
}
diff --git a/src/runtime/os_darwin.go b/src/runtime/os_darwin.go
index 0ecbea7..6eab3b5 100644
--- a/src/runtime/os_darwin.go
+++ b/src/runtime/os_darwin.go
@@ -344,8 +344,11 @@
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) {
}
diff --git a/src/runtime/os_dragonfly.go b/src/runtime/os_dragonfly.go
index a02696e..9b32350 100644
--- a/src/runtime/os_dragonfly.go
+++ b/src/runtime/os_dragonfly.go
@@ -216,8 +216,11 @@
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) {
}
diff --git a/src/runtime/os_linux.go b/src/runtime/os_linux.go
index 8b3c4d0..fb46b81 100644
--- a/src/runtime/os_linux.go
+++ b/src/runtime/os_linux.go
@@ -412,13 +412,12 @@
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
diff --git a/src/runtime/os_netbsd.go b/src/runtime/os_netbsd.go
index 735ace2..a06e5fe 100644
--- a/src/runtime/os_netbsd.go
+++ b/src/runtime/os_netbsd.go
@@ -320,8 +320,11 @@
// 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) {
}
diff --git a/src/runtime/os_openbsd.go b/src/runtime/os_openbsd.go
index 574bfa8..4ce4c3c 100644
--- a/src/runtime/os_openbsd.go
+++ b/src/runtime/os_openbsd.go
@@ -182,8 +182,11 @@
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) {
}
diff --git a/src/runtime/os_plan9.go b/src/runtime/os_plan9.go
index 2dbb42a..3b5965a 100644
--- a/src/runtime/os_plan9.go
+++ b/src/runtime/os_plan9.go
@@ -217,8 +217,11 @@
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) {
}
diff --git a/src/runtime/os_windows.go b/src/runtime/os_windows.go
index 7183e79..54407a3 100644
--- a/src/runtime/os_windows.go
+++ b/src/runtime/os_windows.go
@@ -906,9 +906,11 @@
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 {
diff --git a/src/runtime/proc.go b/src/runtime/proc.go
index e9873e5..21bee4d 100644
--- a/src/runtime/proc.go
+++ b/src/runtime/proc.go
@@ -1935,6 +1935,9 @@
mp.gsignal = nil
}
+ // Free vgetrandom state.
+ vgetrandomDestroy(mp)
+
// Remove m from allm.
lock(&sched.lock)
for pprev := &allm; *pprev != nil; pprev = &(*pprev).alllink {
diff --git a/src/runtime/vgetrandom_linux.go b/src/runtime/vgetrandom_linux.go
index a6ec4b7..40be022 100644
--- a/src/runtime/vgetrandom_linux.go
+++ b/src/runtime/vgetrandom_linux.go
@@ -73,9 +73,16 @@
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)
}
diff --git a/src/runtime/vgetrandom_unsupported.go b/src/runtime/vgetrandom_unsupported.go
index 070392c..43c53e1 100644
--- a/src/runtime/vgetrandom_unsupported.go
+++ b/src/runtime/vgetrandom_unsupported.go
@@ -13,6 +13,6 @@
return -1, false
}
-func vgetrandomPutState(state uintptr) {}
+func vgetrandomDestroy(mp *m) {}
func vgetrandomInit() {}