On Wed, 21 Aug 2019 11:26:25 +0800 Joseph Qi <joseph...@linux.alibaba.com> 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?
