From 6b37b15d9520f9fa2b819e66a37fac4b2d08da78 Mon Sep 17 00:00:00 2001 From: Michael Pratt Date: Tue, 17 Nov 2020 11:55:53 -0500 Subject: runtime: don't take allglock in tracebackothers tracebackothers is called from fatal throw/panic. A fatal throw may be taken with allglock held (notably in the allocator when allglock is held), which would cause a deadlock in tracebackothers when we try to take allglock again. Locking allglock here is also often a lock order violation w.r.t. the locks held when throw was called. Avoid the deadlock and ordering issues by skipping locking altogether. It is OK to miss concurrently created Gs (which are generally avoided by freezetheworld(), and which were possible previously anyways if created after the loop). Fatal throw/panic freezetheworld(), which should freeze other threads that may be racing to modify allgs. However, freezetheworld() does _not_ guarantee that it stops all other threads, so we can't simply drop the lock. Fixes #42669 Updates #43175 Change-Id: I657aec46ed35fd5d1b3f1ba25b500128ab26b088 Reviewed-on: https://go-review.googlesource.com/c/go/+/270861 Reviewed-by: Michael Knyszek Trust: Michael Pratt --- src/runtime/runtime2.go | 1 - 1 file changed, 1 deletion(-) (limited to 'src/runtime/runtime2.go') diff --git a/src/runtime/runtime2.go b/src/runtime/runtime2.go index c9376827da..109f0da131 100644 --- a/src/runtime/runtime2.go +++ b/src/runtime/runtime2.go @@ -1052,7 +1052,6 @@ func (w waitReason) String() string { } var ( - allglen uintptr allm *m gomaxprocs int32 ncpu int32 -- cgit v1.3-5-g9baa