From: "Rafael J. Wysocki" <rafael@kernel.org>
To: Stanislaw Gruszka <stanislaw.gruszka@linux.intel.com>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>,
"Rafael J. Wysocki" <rjw@rjwysocki.net>,
Greg KH <gregkh@linuxfoundation.org>,
linux-pm@vger.kernel.org,
Youngmin Nam <youngmin.nam@samsung.com>,
linux-kernel@vger.kernel.org, d7271.choe@samsung.com,
janghyuck.kim@samsung.com, hyesoo.yu@samsung.com,
Alan Stern <stern@rowland.harvard.edu>,
Ulf Hansson <ulf.hansson@linaro.org>
Subject: Re: [PATCH v1 2/3] async: Introduce async_schedule_dev_nocall()
Date: Tue, 2 Jan 2024 14:15:17 +0100 [thread overview]
Message-ID: <CAJZ5v0gKJp7zuFruZm3z8QJu068kP75ngW1cMh2OftEzTm_4Jw@mail.gmail.com> (raw)
In-Reply-To: <ZZO2v0lQSZLxNV3c@linux.intel.com>
On Tue, Jan 2, 2024 at 8:10 AM Stanislaw Gruszka
<stanislaw.gruszka@linux.intel.com> wrote:
>
> On Fri, Dec 29, 2023 at 05:36:01PM +0100, Rafael J. Wysocki wrote:
> > On Fri, Dec 29, 2023 at 3:54 PM Stanislaw Gruszka
> > <stanislaw.gruszka@linux.intel.com> wrote:
> > >
> > > On Fri, Dec 29, 2023 at 02:37:36PM +0100, Rafael J. Wysocki wrote:
> > > > > > +bool async_schedule_dev_nocall(async_func_t func, struct device *dev)
> > > > > > +{
> > > > > > + struct async_entry *entry;
> > > > > > +
> > > > > > + entry = kzalloc(sizeof(struct async_entry), GFP_KERNEL);
> > > > >
> > > > > Is GFP_KERNEL intended here ?
> > > >
> > > > Yes, it is.
> > > >
> > > > PM will be the only user of this, at least for now, and it all runs in
> > > > process context.
> > > >
> > > > > I think it's not safe since will
> > > > > be called from device_resume_noirq() .
> > > >
> > > > device_resume_noirq() runs in process context too.
> > > >
> > > > The name is somewhat confusing (sorry about that) and it means that
> > > > hardirq handlers (for the majority of IRQs) don't run in that resume
> > > > phase, but interrupts are enabled locally on all CPUs (this is
> > > > required for wakeup handling, among other things).
> > >
> > > Then my concern would be: if among devices with disabled IRQs are
> > > disk devices? Seems there are disk devices as well, and because
> > > GFP_KERNEL can start reclaiming memory by doing disk IO (write
> > > dirty pages for example), with disk driver interrupts disabled
> > > reclaiming process can not finish.
> > >
> > > I do not see how such possible infinite waiting for disk IO
> > > scenario is prevented here, did I miss something?
> >
> > Well, it is not a concern, because the suspend code already prevents
> > the mm subsystem from trying too hard to find free memory. See the
> > pm_restrict_gfp_mask() call in enter_state().
>
> So that I missed :-) Thanks for explanations.
>
> Reviewed-by: Stanislaw Gruszka <stanislaw.gruszka@linux.intel.com> for the series.
Thank you!
next prev parent reply other threads:[~2024-01-02 13:15 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <CGME20231227084252epcas2p3b063f7852f81f82cd0a31afd7f404db4@epcas2p3.samsung.com>
2023-12-27 8:42 ` [BUG] mutex deadlock of dpm_resume() in low memory situation Youngmin Nam
2023-12-27 16:08 ` Greg KH
2023-12-27 17:44 ` Rafael J. Wysocki
2023-12-27 18:39 ` Rafael J. Wysocki
2023-12-27 18:58 ` Rafael J. Wysocki
2023-12-27 20:50 ` Rafael J. Wysocki
2023-12-28 6:40 ` Youngmin Nam
2023-12-27 20:35 ` [PATCH v1 0/3] PM: sleep: Fix possible device suspend-resume deadlocks Rafael J. Wysocki
2023-12-27 20:37 ` [PATCH v1 1/3] async: Split async_schedule_node_domain() Rafael J. Wysocki
2023-12-27 20:38 ` [PATCH v1 2/3] async: Introduce async_schedule_dev_nocall() Rafael J. Wysocki
2023-12-28 20:29 ` Stanislaw Gruszka
2023-12-29 13:37 ` Rafael J. Wysocki
2023-12-29 3:08 ` Stanislaw Gruszka
2023-12-29 16:36 ` Rafael J. Wysocki
2024-01-02 7:09 ` Stanislaw Gruszka
2024-01-02 13:15 ` Rafael J. Wysocki [this message]
2023-12-27 20:41 ` [PATCH v1 3/3] PM: sleep: Fix possible deadlocks in core system-wide PM code Rafael J. Wysocki
2024-01-02 13:35 ` Ulf Hansson
2024-01-02 13:53 ` Rafael J. Wysocki
2024-01-03 10:17 ` Ulf Hansson
2024-01-03 10:27 ` Rafael J. Wysocki
2024-01-03 10:33 ` Greg KH
2024-01-02 13:18 ` [PATCH v1 0/3] PM: sleep: Fix possible device suspend-resume deadlocks Rafael J. Wysocki
2024-01-03 4:39 ` Youngmin Nam
2024-01-03 10:28 ` Rafael J. Wysocki
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