From: Peter Zijlstra <peterz@infradead.org>
To: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: vincent.guittot@linaro.org, linux-pm@vger.kernel.org,
bigeasy@linutronix.de, amit@kernel.org, rjw@rjwysocki.net,
linux-kernel@vger.kernel.org, rostedt@goodmis.org,
mingo@kernel.org, Marc Hartmayer <mhartmay@linux.ibm.com>,
mgorman@suse.de, oleg@redhat.com, tj@kernel.org,
virtualization@lists.linux-foundation.org, will@kernel.org,
dietmar.eggemann@arm.com, ebiederm@xmission.com
Subject: Re: [PATCH v3 6/6] freezer,sched: Rewrite core freezer logic
Date: Mon, 26 Sep 2022 14:13:53 +0200 [thread overview]
Message-ID: <YzGXgbfRngNfDhoC@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <436fa401-e113-0393-f47a-ed23890364d7@linux.ibm.com>
On Mon, Sep 26, 2022 at 12:55:21PM +0200, Christian Borntraeger wrote:
>
>
> Am 26.09.22 um 10:06 schrieb Christian Borntraeger:
> >
> >
> > Am 23.09.22 um 09:53 schrieb Christian Borntraeger:
> > > Am 23.09.22 um 09:21 schrieb Christian Borntraeger:
> > > > Peter,
> > > >
> > > > as a heads-up. This commit (bisected and verified) triggers a
> > > > regression in our KVM on s390x CI. The symptom is that a specific
> > > > testcase (start a guest with next kernel and a poky ramdisk,
> > > > then ssh via vsock into the guest and run the reboot command) now
> > > > takes much longer (300 instead of 20 seconds). From a first look
> > > > it seems that the sshd takes very long to end during shutdown
> > > > but I have not looked into that yet.
> > > > Any quick idea?
> > > >
> > > > Christian
> > >
> > > the sshd seems to hang in virtio-serial (not vsock).
> >
> > FWIW, sshd does not seem to hang, instead it seems to busy loop in
> > wait_port_writable calling into the scheduler over and over again.
>
> -#define TASK_FREEZABLE 0x00002000
> +#define TASK_FREEZABLE 0x00000000
>
> "Fixes" the issue. Just have to find out which of users is responsible.
Since it's not the wait_port_writable() one -- we already tested that by
virtue of 's/wait_event_freezable/wait_event/' there, it must be on the
producing side of that port. But I'm having a wee bit of trouble
following that code.
Is there a task stuck in FROZEN state? -- then again, I thought you said
there was no actual suspend involved, so that should not be it either.
I'm curious though -- how far does it get into the scheduler? It should
call schedule() with __state == TASK_INTERRUPTIBLE|TASK_FREEZABLE, which
is quite sufficient to get it off the runqueue, who then puts it back?
Or is it bailing early in the wait_event loop?
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WARNING: multiple messages have this Message-ID (diff)
From: Peter Zijlstra <peterz@infradead.org>
To: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: bigeasy@linutronix.de, dietmar.eggemann@arm.com,
ebiederm@xmission.com, linux-kernel@vger.kernel.org,
linux-pm@vger.kernel.org, mgorman@suse.de, mingo@kernel.org,
oleg@redhat.com, rjw@rjwysocki.net, rostedt@goodmis.org,
tj@kernel.org, vincent.guittot@linaro.org, will@kernel.org,
Marc Hartmayer <mhartmay@linux.ibm.com>,
amit@kernel.org, virtualization@lists.linux-foundation.org
Subject: Re: [PATCH v3 6/6] freezer,sched: Rewrite core freezer logic
Date: Mon, 26 Sep 2022 14:13:53 +0200 [thread overview]
Message-ID: <YzGXgbfRngNfDhoC@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <436fa401-e113-0393-f47a-ed23890364d7@linux.ibm.com>
On Mon, Sep 26, 2022 at 12:55:21PM +0200, Christian Borntraeger wrote:
>
>
> Am 26.09.22 um 10:06 schrieb Christian Borntraeger:
> >
> >
> > Am 23.09.22 um 09:53 schrieb Christian Borntraeger:
> > > Am 23.09.22 um 09:21 schrieb Christian Borntraeger:
> > > > Peter,
> > > >
> > > > as a heads-up. This commit (bisected and verified) triggers a
> > > > regression in our KVM on s390x CI. The symptom is that a specific
> > > > testcase (start a guest with next kernel and a poky ramdisk,
> > > > then ssh via vsock into the guest and run the reboot command) now
> > > > takes much longer (300 instead of 20 seconds). From a first look
> > > > it seems that the sshd takes very long to end during shutdown
> > > > but I have not looked into that yet.
> > > > Any quick idea?
> > > >
> > > > Christian
> > >
> > > the sshd seems to hang in virtio-serial (not vsock).
> >
> > FWIW, sshd does not seem to hang, instead it seems to busy loop in
> > wait_port_writable calling into the scheduler over and over again.
>
> -#define TASK_FREEZABLE 0x00002000
> +#define TASK_FREEZABLE 0x00000000
>
> "Fixes" the issue. Just have to find out which of users is responsible.
Since it's not the wait_port_writable() one -- we already tested that by
virtue of 's/wait_event_freezable/wait_event/' there, it must be on the
producing side of that port. But I'm having a wee bit of trouble
following that code.
Is there a task stuck in FROZEN state? -- then again, I thought you said
there was no actual suspend involved, so that should not be it either.
I'm curious though -- how far does it get into the scheduler? It should
call schedule() with __state == TASK_INTERRUPTIBLE|TASK_FREEZABLE, which
is quite sufficient to get it off the runqueue, who then puts it back?
Or is it bailing early in the wait_event loop?
next prev parent reply other threads:[~2022-09-26 12:14 UTC|newest]
Thread overview: 94+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-08-22 11:18 [PATCH v3 0/6] Freezer Rewrite Peter Zijlstra
2022-08-22 11:18 ` [PATCH v3 1/6] freezer: Have {,un}lock_system_sleep() save/restore flags Peter Zijlstra
2022-08-23 17:25 ` Rafael J. Wysocki
2022-09-09 9:00 ` [tip: sched/core] " tip-bot2 for Peter Zijlstra
2022-08-22 11:18 ` [PATCH v3 2/6] freezer,umh: Clean up freezer/initrd interaction Peter Zijlstra
2022-08-23 17:28 ` Rafael J. Wysocki
2022-09-09 9:00 ` [tip: sched/core] " tip-bot2 for Peter Zijlstra
2022-08-22 11:18 ` [PATCH v3 3/6] sched: Change wait_task_inactive()s match_state Peter Zijlstra
2022-09-04 10:44 ` Ingo Molnar
2022-09-06 10:54 ` Peter Zijlstra
2022-09-07 7:23 ` Ingo Molnar
2022-09-07 9:29 ` Peter Zijlstra
2022-09-09 9:00 ` [tip: sched/core] sched: Rename task_running() to task_on_cpu() tip-bot2 for Peter Zijlstra
2022-09-07 9:30 ` [PATCH v3 3/6] sched: Change wait_task_inactive()s match_state Peter Zijlstra
2022-09-09 9:00 ` [tip: sched/core] " tip-bot2 for Peter Zijlstra
2022-08-22 11:18 ` [PATCH v3 4/6] sched/completion: Add wait_for_completion_state() Peter Zijlstra
2022-08-23 17:32 ` Rafael J. Wysocki
2022-08-26 21:54 ` Peter Zijlstra
2022-09-04 10:46 ` Ingo Molnar
2022-09-06 10:24 ` Peter Zijlstra
2022-09-07 7:35 ` Ingo Molnar
2022-09-07 9:24 ` Peter Zijlstra
2022-09-09 9:00 ` [tip: sched/core] " tip-bot2 for Peter Zijlstra
2022-08-22 11:18 ` [PATCH v3 5/6] sched/wait: Add wait_event_state() Peter Zijlstra
2022-09-04 9:54 ` Ingo Molnar
2022-09-06 11:08 ` Peter Zijlstra
2022-09-07 7:26 ` Ingo Molnar
2022-09-09 9:00 ` [tip: sched/core] " tip-bot2 for Peter Zijlstra
2022-08-22 11:18 ` [PATCH v3 6/6] freezer,sched: Rewrite core freezer logic Peter Zijlstra
2022-08-23 17:36 ` Rafael J. Wysocki
2022-09-04 10:09 ` Ingo Molnar
2022-09-06 11:23 ` Peter Zijlstra
2022-09-07 7:30 ` Ingo Molnar
2022-09-09 9:00 ` [tip: sched/core] sched: Show PF_flag holes tip-bot2 for Peter Zijlstra
2022-09-09 9:00 ` [tip: sched/core] freezer,sched: Rewrite core freezer logic tip-bot2 for Peter Zijlstra
2022-09-23 7:21 ` [PATCH v3 6/6] " Christian Borntraeger
2022-09-23 7:53 ` Christian Borntraeger
2022-09-26 8:06 ` Christian Borntraeger
2022-09-26 10:55 ` Christian Borntraeger
2022-09-26 12:13 ` Peter Zijlstra [this message]
2022-09-26 12:13 ` Peter Zijlstra
2022-09-26 12:32 ` Christian Borntraeger
2022-09-26 12:32 ` Christian Borntraeger
2022-09-26 12:55 ` Peter Zijlstra
2022-09-26 12:55 ` Peter Zijlstra
2022-09-26 13:23 ` Christian Borntraeger
2022-09-26 13:23 ` Christian Borntraeger
2022-09-26 13:37 ` Peter Zijlstra
2022-09-26 13:37 ` Peter Zijlstra
2022-09-26 13:54 ` Christian Borntraeger
2022-09-26 13:54 ` Christian Borntraeger
2022-09-26 15:49 ` Christian Borntraeger
2022-09-26 15:49 ` Christian Borntraeger
2022-09-26 18:06 ` Peter Zijlstra
2022-09-26 18:06 ` Peter Zijlstra
2022-09-26 18:22 ` Peter Zijlstra
2022-09-26 18:22 ` Peter Zijlstra
2022-09-27 5:35 ` Christian Borntraeger
2022-09-27 5:35 ` Christian Borntraeger
2022-09-28 5:44 ` Christian Borntraeger
2022-09-28 5:44 ` Christian Borntraeger
2022-10-21 17:22 ` Ville Syrjälä
2022-10-21 17:22 ` [Intel-gfx] [PATCH v3 6/6] freezer, sched: " Ville Syrjälä
2022-10-25 4:52 ` [PATCH v3 6/6] freezer,sched: " Ville Syrjälä
2022-10-25 4:52 ` [Intel-gfx] [PATCH v3 6/6] freezer, sched: " Ville Syrjälä
2022-10-25 10:49 ` [PATCH v3 6/6] freezer,sched: " Peter Zijlstra
2022-10-25 10:49 ` [Intel-gfx] [PATCH v3 6/6] freezer, sched: " Peter Zijlstra
2022-10-26 10:32 ` [PATCH v3 6/6] freezer,sched: " Ville Syrjälä
2022-10-26 10:32 ` [Intel-gfx] [PATCH v3 6/6] freezer, sched: " Ville Syrjälä
2022-10-26 11:43 ` Peter Zijlstra
2022-10-26 11:43 ` [PATCH v3 6/6] freezer,sched: " Peter Zijlstra
2022-10-26 12:12 ` [Intel-gfx] [PATCH v3 6/6] freezer, sched: " Peter Zijlstra
2022-10-26 12:12 ` [PATCH v3 6/6] freezer,sched: " Peter Zijlstra
2022-10-26 12:14 ` Peter Zijlstra
2022-10-26 12:14 ` [Intel-gfx] [PATCH v3 6/6] freezer, sched: " Peter Zijlstra
2022-10-27 5:58 ` [PATCH v3 6/6] freezer,sched: " Chen Yu
2022-10-27 5:58 ` [Intel-gfx] [PATCH v3 6/6] freezer, sched: " Chen Yu
2022-10-27 7:39 ` [PATCH v3 6/6] freezer,sched: " Peter Zijlstra
2022-10-27 7:39 ` [Intel-gfx] [PATCH v3 6/6] freezer, sched: " Peter Zijlstra
2022-10-27 13:09 ` [PATCH v3 6/6] freezer,sched: " Ville Syrjälä
2022-10-27 13:09 ` [Intel-gfx] [PATCH v3 6/6] freezer, sched: " Ville Syrjälä
2022-10-27 16:53 ` [PATCH v3 6/6] freezer,sched: " Peter Zijlstra
2022-10-27 16:53 ` [Intel-gfx] [PATCH v3 6/6] freezer, sched: " Peter Zijlstra
2022-11-02 16:57 ` [PATCH v3 6/6] freezer,sched: " Ville Syrjälä
2022-11-02 16:57 ` [Intel-gfx] [PATCH v3 6/6] freezer, sched: " Ville Syrjälä
2022-11-02 22:16 ` [PATCH v3 6/6] freezer,sched: " Peter Zijlstra
2022-11-02 22:16 ` [Intel-gfx] [PATCH v3 6/6] freezer, sched: " Peter Zijlstra
2022-11-07 11:47 ` [PATCH v3 6/6] freezer,sched: " Ville Syrjälä
2022-11-07 11:47 ` [Intel-gfx] [PATCH v3 6/6] freezer, sched: " Ville Syrjälä
2022-11-10 20:27 ` Ville Syrjälä
2022-11-10 20:27 ` Ville Syrjälä
2022-11-14 9:10 ` [tip: sched/urgent] sched: Fix race in task_call_func() tip-bot2 for Peter Zijlstra
-- strict thread matches above, loose matches on Subject: below --
2021-10-09 10:07 [PATCH v3 0/6] Freezer rewrite Peter Zijlstra
2021-10-09 10:08 ` [PATCH v3 6/6] freezer,sched: Rewrite core freezer logic Peter Zijlstra
2021-10-18 13:36 ` Peter Zijlstra
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