On Thu, Aug 22, 2019 at 3:21 PM Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> wrote: > > On Wed, 21 Aug 2019 11:26:25 +0800 Joseph Qi <joseph.qi@xxxxxxxxxxxxxxxxx> wrote: > > > Only when calling the poll syscall the first time can user > > receive POLLPRI correctly. After that, user always fails to > > acquire the event signal. > > > > Reproduce case: > > 1. Get the monitor code in Documentation/accounting/psi.txt > > 2. Run it, and wait for the event triggered. > > 3. Kill and restart the process. > > > > The question is why we can end up with poll_scheduled = 1 but the work > > not running (which would reset it to 0). And the answer is because the > > scheduling side sees group->poll_kworker under RCU protection and then > > schedules it, but here we cancel the work and destroy the worker. The > > cancel needs to pair with resetting the poll_scheduled flag. > > Should this be backported into -stable kernels? Adding GregKH and stable@xxxxxxxxxxxxxxx I was able to cleanly apply this patch to stable master and linux-5.2.y branches (these are the only branches that have psi triggers). Greg, Andrew got this patch into -mm tree. Please advise on how we should proceed to land it in stable 5.2.y and master. Thanks, Suren.
