BACKPORT: workqueue: skip nr_running sanity check in worker_enter_idle() if trustee is active
worker_enter_idle() has WARN_ON_ONCE() which triggers if nr_running
isn't zero when every worker is idle. This can trigger spuriously
while a cpu is going down due to the way trustee sets %WORKER_ROGUE
and zaps nr_running.
It first sets %WORKER_ROGUE on all workers without updating
nr_running, releases gcwq->lock, schedules, regrabs gcwq->lock and
then zaps nr_running. If the last running worker enters idle
inbetween, it would see stale nr_running which hasn't been zapped yet
and trigger the WARN_ON_ONCE().
Fix it by performing the sanity check iff the trustee is idle.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: stable@vger.kernel.org
(cherry picked from commit 544ecf310f0e7f51fa057ac2a295fc1b3b35a9d3)
Signed-off-by: Stéphane Marchesin <marcheu@chromium.org>
BUG=chromium:367862
TEST=builds and runs on stumpy
Change-Id: Iad3094edcd35f589ac73714d1cbe52e7b08b9fe5
Reviewed-on: https://chromium-review.googlesource.com/197923
Tested-by: Stéphane Marchesin <marcheu@chromium.org>
Reviewed-by: Olof Johansson <olofj@chromium.org>
Commit-Queue: Stéphane Marchesin <marcheu@chromium.org>
1 file changed
