On Wed, Jan 11, 2017 at 05:43:02PM +0100, Peter Zijlstra wrote: > On Mon, Jan 09, 2017 at 11:52:03AM +0000, Chris Wilson wrote: > > If we abort the mutex_lock() due to an interrupt, or other error from > > s/interrupt/signal/, right?
Yes. EINTR is ingrained. > > ww_mutex, we need to relinquish the handoff flag if we applied it. > > Otherwise, we may cause missed wakeups as the current owner may try to > > handoff to a new thread that is not expecting the handoff and so sleep > > thinking the lock is already claimed (and since the owner unlocked there > > may never be a new wakeup). > > Isn't that the exact same scenario as Nicolai fixed here: > > http://lkml.kernel.org/r/1482346000-9927-3-git-send-email-nhaeh...@gmail.com > > Did you, like Nicolai, find this by inspection, or can you reproduce? Looks like it should be. It takes about 20 minutes of running a stress test, but it is very reliably hit on the current kernel. > FWIW, I have the below patch that should also solve this problem afaict. Thanks, I shall see if makes my machines happy. -Chris -- Chris Wilson, Intel Open Source Technology Centre
