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Date: Wed, 11 May 2016 20:03:46 +0200 From: Michal Hocko <mhocko@...nel.org> To: Peter Zijlstra <peterz@...radead.org> Cc: Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>, LKML <linux-kernel@...r.kernel.org>, Ingo Molnar <mingo@...hat.com>, Thomas Gleixner <tglx@...utronix.de>, "H. Peter Anvin" <hpa@...or.com>, "David S. Miller" <davem@...emloft.net>, Tony Luck <tony.luck@...el.com>, Andrew Morton <akpm@...ux-foundation.org>, Chris Zankel <chris@...kel.net>, Max Filippov <jcmvbkbc@...il.com>, Davidlohr Bueso <dave@...olabs.net>, Waiman Long <Waiman.Long@....com> Subject: Re: [PATCH 03/11] locking, rwsem: introduce basis for down_write_killable On Wed 11-05-16 15:59:38, Michal Hocko wrote: > On Wed 11-05-16 11:41:28, Peter Zijlstra wrote: > > On Wed, May 11, 2016 at 11:31:27AM +0200, Michal Hocko wrote: > > > > > Care to cook up a full patch? > > > > compile tested only, if someone could please test it? > > I have tried to run the test case from Tetsuo[1] with a small printk to > show the interrupted writer case: > [ 2753.596678] XXX: Writer interrupted. Woken waiters:0 > [ 2998.266978] XXX: Writer interrupted. Woken waiters:0 > > which means rwsem_atomic_update(-RWSEM_WAITING_BIAS, sem) path which is > the problematic case. oom_reaper was always able to succeed so I guess > the patch works as expected. I will leave the test run for longer to be > sure. And just for the reference I am able to reproduce the lockup without the patch applied and the same test case and a debugging patch [ 1522.036379] XXX interrupted. list_is_singular:1 [ 1523.040462] oom_reaper: unable to reap pid:3736 (tgid=3736) I still cannot say I would understand why the pending RWSEM_WAITING_BIAS matters but I would probably need to look at the code again with a clean head, __rwsem_wake is quite tricky... -- Michal Hocko SUSE Labs
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