runtime.bgsweep contains an infinite loop. With aggressive enough
inlining, it may not perform any CALLs on a typical iteration. If
the runtime trying to preempt this goroutine, the lack of CALLs may
prevent preemption for ever occurring.
bgsweep does happen to call goschedIfBusy. Add a preempt check there to
make sure we yield eventually.
For #55022.
Change-Id: If22eb86fd6a626094b3c56dc745c8e4243b0fb40
Reviewed-on: https://go-review.googlesource.com/c/go/+/447135
Run-TryBot: Michael Pratt <mpratt@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org> Reviewed-by: Michael Knyszek <mknyszek@google.com> Reviewed-by: Cherry Mui <cherryyz@google.com>