From: ebiederm@xmission.com (Eric W. Biederman) To: Andrey Grodzovsky <andrey.grodzovsky@amd.com> Cc: <linux-kernel@vger.kernel.org>, <amd-gfx@lists.freedesktop.org>, <Alexander.Deucher@amd.com>, <Christian.Koenig@amd.com>, <David.Panariti@amd.com>, <oleg@redhat.com>, <akpm@linux-foundation.org> Subject: Re: [PATCH 2/3] drm/scheduler: Don't call wait_event_killable for signaled process. Date: Tue, 24 Apr 2018 11:23:18 -0500 [thread overview] Message-ID: <87muxsbmkp.fsf@xmission.com> (raw) In-Reply-To: <1524583836-12130-3-git-send-email-andrey.grodzovsky@amd.com> (Andrey Grodzovsky's message of "Tue, 24 Apr 2018 11:30:35 -0400") Andrey Grodzovsky <andrey.grodzovsky@amd.com> writes: > Avoid calling wait_event_killable when you are possibly being called > from get_signal routine since in that case you end up in a deadlock > where you are alreay blocked in singla processing any trying to wait > on a new signal. I am curious what the call path that is problematic here. In general waiting seems wrong when the process has already been fatally killed as indicated by PF_SIGNALED. Returning -ERESTARTSYS seems wrong as nothing should make it back even to the edge of userspace here. Given that this is the only use of PF_SIGNALED outside of bsd process accounting I find this code very suspicious. It looks the code path that gets called during exit is buggy and needs to be sorted out. Eric > Signed-off-by: Andrey Grodzovsky <andrey.grodzovsky@amd.com> > --- > drivers/gpu/drm/scheduler/gpu_scheduler.c | 5 +++-- > 1 file changed, 3 insertions(+), 2 deletions(-) > > diff --git a/drivers/gpu/drm/scheduler/gpu_scheduler.c b/drivers/gpu/drm/scheduler/gpu_scheduler.c > index 088ff2b..09fd258 100644 > --- a/drivers/gpu/drm/scheduler/gpu_scheduler.c > +++ b/drivers/gpu/drm/scheduler/gpu_scheduler.c > @@ -227,9 +227,10 @@ void drm_sched_entity_do_release(struct drm_gpu_scheduler *sched, > return; > /** > * The client will not queue more IBs during this fini, consume existing > - * queued IBs or discard them on SIGKILL > + * queued IBs or discard them when in death signal state since > + * wait_event_killable can't receive signals in that state. > */ > - if ((current->flags & PF_SIGNALED) && current->exit_code == SIGKILL) > + if (current->flags & PF_SIGNALED) > entity->fini_status = -ERESTARTSYS; > else > entity->fini_status = wait_event_killable(sched->job_scheduled,
WARNING: multiple messages have this Message-ID (diff)
From: ebiederm@xmission.com (Eric W. Biederman) To: Andrey Grodzovsky <andrey.grodzovsky@amd.com> Cc: linux-kernel@vger.kernel.org, amd-gfx@lists.freedesktop.org, Alexander.Deucher@amd.com, Christian.Koenig@amd.com, David.Panariti@amd.com, oleg@redhat.com, akpm@linux-foundation.org Subject: Re: [PATCH 2/3] drm/scheduler: Don't call wait_event_killable for signaled process. Date: Tue, 24 Apr 2018 11:23:18 -0500 [thread overview] Message-ID: <87muxsbmkp.fsf@xmission.com> (raw) In-Reply-To: <1524583836-12130-3-git-send-email-andrey.grodzovsky@amd.com> (Andrey Grodzovsky's message of "Tue, 24 Apr 2018 11:30:35 -0400") Andrey Grodzovsky <andrey.grodzovsky@amd.com> writes: > Avoid calling wait_event_killable when you are possibly being called > from get_signal routine since in that case you end up in a deadlock > where you are alreay blocked in singla processing any trying to wait > on a new signal. I am curious what the call path that is problematic here. In general waiting seems wrong when the process has already been fatally killed as indicated by PF_SIGNALED. Returning -ERESTARTSYS seems wrong as nothing should make it back even to the edge of userspace here. Given that this is the only use of PF_SIGNALED outside of bsd process accounting I find this code very suspicious. It looks the code path that gets called during exit is buggy and needs to be sorted out. Eric > Signed-off-by: Andrey Grodzovsky <andrey.grodzovsky@amd.com> > --- > drivers/gpu/drm/scheduler/gpu_scheduler.c | 5 +++-- > 1 file changed, 3 insertions(+), 2 deletions(-) > > diff --git a/drivers/gpu/drm/scheduler/gpu_scheduler.c b/drivers/gpu/drm/scheduler/gpu_scheduler.c > index 088ff2b..09fd258 100644 > --- a/drivers/gpu/drm/scheduler/gpu_scheduler.c > +++ b/drivers/gpu/drm/scheduler/gpu_scheduler.c > @@ -227,9 +227,10 @@ void drm_sched_entity_do_release(struct drm_gpu_scheduler *sched, > return; > /** > * The client will not queue more IBs during this fini, consume existing > - * queued IBs or discard them on SIGKILL > + * queued IBs or discard them when in death signal state since > + * wait_event_killable can't receive signals in that state. > */ > - if ((current->flags & PF_SIGNALED) && current->exit_code == SIGKILL) > + if (current->flags & PF_SIGNALED) > entity->fini_status = -ERESTARTSYS; > else > entity->fini_status = wait_event_killable(sched->job_scheduled,
next prev parent reply other threads:[~2018-04-24 16:24 UTC|newest] Thread overview: 122+ messages / expand[flat|nested] mbox.gz Atom feed top 2018-04-24 15:30 Avoid uninterruptible sleep during process exit Andrey Grodzovsky 2018-04-24 15:30 ` Andrey Grodzovsky 2018-04-24 15:30 ` [PATCH 1/3] signals: Allow generation of SIGKILL to exiting task Andrey Grodzovsky 2018-04-24 15:30 ` Andrey Grodzovsky 2018-04-24 16:10 ` Eric W. Biederman 2018-04-24 16:10 ` Eric W. Biederman 2018-04-24 16:42 ` Eric W. Biederman 2018-04-24 16:42 ` Eric W. Biederman 2018-04-24 16:51 ` Andrey Grodzovsky 2018-04-24 16:51 ` Andrey Grodzovsky 2018-04-24 17:29 ` Eric W. Biederman 2018-04-25 13:13 ` Oleg Nesterov 2018-04-24 15:30 ` [PATCH 2/3] drm/scheduler: Don't call wait_event_killable for signaled process Andrey Grodzovsky 2018-04-24 15:30 ` Andrey Grodzovsky 2018-04-24 15:46 ` Michel Dänzer 2018-04-24 15:51 ` Andrey Grodzovsky 2018-04-24 15:51 ` Andrey Grodzovsky 2018-04-24 15:52 ` Andrey Grodzovsky 2018-04-24 15:52 ` Andrey Grodzovsky 2018-04-24 19:44 ` Daniel Vetter 2018-04-24 19:44 ` Daniel Vetter 2018-04-24 21:00 ` Eric W. Biederman 2018-04-24 21:02 ` Andrey Grodzovsky 2018-04-24 21:02 ` Andrey Grodzovsky 2018-04-24 21:21 ` Eric W. Biederman 2018-04-24 21:37 ` Andrey Grodzovsky 2018-04-24 21:37 ` Andrey Grodzovsky 2018-04-24 22:11 ` Eric W. Biederman 2018-04-25 7:14 ` Daniel Vetter 2018-04-25 13:08 ` Andrey Grodzovsky 2018-04-25 13:08 ` Andrey Grodzovsky 2018-04-25 15:29 ` Eric W. Biederman 2018-04-25 16:13 ` Andrey Grodzovsky 2018-04-25 16:31 ` Eric W. Biederman 2018-04-24 21:40 ` Daniel Vetter 2018-04-24 21:40 ` Daniel Vetter 2018-04-25 13:22 ` Oleg Nesterov 2018-04-25 13:36 ` Daniel Vetter 2018-04-25 14:18 ` Oleg Nesterov 2018-04-25 14:18 ` Oleg Nesterov 2018-04-25 13:43 ` Andrey Grodzovsky 2018-04-25 13:43 ` Andrey Grodzovsky 2018-04-24 16:23 ` Eric W. Biederman [this message] 2018-04-24 16:23 ` Eric W. Biederman 2018-04-24 16:43 ` Andrey Grodzovsky 2018-04-24 16:43 ` Andrey Grodzovsky 2018-04-24 17:12 ` Eric W. Biederman 2018-04-25 13:55 ` Oleg Nesterov 2018-04-25 14:21 ` Andrey Grodzovsky 2018-04-25 14:21 ` Andrey Grodzovsky 2018-04-25 17:17 ` Oleg Nesterov 2018-04-25 18:40 ` Andrey Grodzovsky 2018-04-25 18:40 ` Andrey Grodzovsky 2018-04-26 0:01 ` Eric W. Biederman 2018-04-26 12:34 ` Andrey Grodzovsky 2018-04-26 12:34 ` Andrey Grodzovsky 2018-04-26 12:52 ` Andrey Grodzovsky 2018-04-26 12:52 ` Andrey Grodzovsky 2018-04-26 15:57 ` Eric W. Biederman 2018-04-26 20:43 ` Andrey Grodzovsky 2018-04-26 20:43 ` Andrey Grodzovsky 2018-04-30 12:08 ` Christian König 2018-04-30 12:08 ` Christian König 2018-04-30 14:32 ` Andrey Grodzovsky 2018-04-30 14:32 ` Andrey Grodzovsky 2018-04-30 15:25 ` Christian König 2018-04-30 15:25 ` Christian König 2018-04-30 16:00 ` Oleg Nesterov 2018-04-30 16:10 ` Andrey Grodzovsky 2018-04-30 16:10 ` Andrey Grodzovsky 2018-04-30 18:29 ` Christian König 2018-04-30 18:29 ` Christian König 2018-04-30 19:28 ` Andrey Grodzovsky 2018-04-30 19:28 ` Andrey Grodzovsky 2018-05-02 11:48 ` Christian König 2018-05-02 11:48 ` Christian König 2018-05-17 11:18 ` Andrey Grodzovsky 2018-05-17 14:48 ` Michel Dänzer 2018-05-17 15:33 ` Andrey Grodzovsky 2018-05-17 15:52 ` Michel Dänzer 2018-05-17 19:05 ` Andrey Grodzovsky 2018-05-18 8:46 ` Michel Dänzer 2018-05-18 9:42 ` Christian König 2018-05-18 14:44 ` Michel Dänzer 2018-05-18 14:50 ` Christian König 2018-05-18 15:02 ` Andrey Grodzovsky 2018-05-22 12:58 ` Christian König 2018-05-22 15:49 ` Andrey Grodzovsky 2018-05-22 16:09 ` Michel Dänzer 2018-05-22 16:30 ` Andrey Grodzovsky 2018-05-22 16:33 ` Michel Dänzer 2018-05-22 16:37 ` Andrey Grodzovsky 2018-05-01 14:35 ` Oleg Nesterov 2018-05-23 15:08 ` Andrey Grodzovsky 2018-05-23 15:08 ` Andrey Grodzovsky 2018-04-30 15:29 ` Oleg Nesterov 2018-04-30 16:25 ` Eric W. Biederman 2018-04-30 17:18 ` Andrey Grodzovsky 2018-04-30 17:18 ` Andrey Grodzovsky 2018-04-25 13:05 ` Oleg Nesterov 2018-04-24 15:30 ` [PATCH 3/3] drm/amdgpu: Switch to interrupted wait to recover from ring hang Andrey Grodzovsky 2018-04-24 15:30 ` Andrey Grodzovsky 2018-04-24 15:52 ` Panariti, David 2018-04-24 15:52 ` Panariti, David 2018-04-24 15:58 ` Andrey Grodzovsky 2018-04-24 15:58 ` Andrey Grodzovsky 2018-04-24 16:20 ` Panariti, David 2018-04-24 16:20 ` Panariti, David 2018-04-24 16:30 ` Eric W. Biederman 2018-04-24 16:30 ` Eric W. Biederman 2018-04-25 17:17 ` Andrey Grodzovsky 2018-04-25 17:17 ` Andrey Grodzovsky 2018-04-25 20:55 ` Eric W. Biederman 2018-04-25 20:55 ` Eric W. Biederman 2018-04-26 12:28 ` Andrey Grodzovsky 2018-04-26 12:28 ` Andrey Grodzovsky 2018-04-24 16:14 ` Eric W. Biederman 2018-04-24 16:14 ` Eric W. Biederman 2018-04-24 16:38 ` Andrey Grodzovsky 2018-04-24 16:38 ` Andrey Grodzovsky 2018-04-30 11:34 ` Christian König 2018-04-30 11:34 ` Christian König
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