linux-kernel - Re: [BUG] mutex deadlock of dpm_resume() in low memory situation

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Message-ID: <CAJZ5v0hGd0LzaBkiPYV3D7fnTm9aVOn6eT84q-_r1Rr-1Vupow@mail.gmail.com>
Date: Wed, 27 Dec 2023 18:44:51 +0100
From: "Rafael J. Wysocki" <rafael@...nel.org>
To: Greg KH <gregkh@...uxfoundation.org>
Cc: Youngmin Nam <youngmin.nam@...sung.com>, rafael@...nel.org, len.brown@...el.com, 
	pavel@....cz, linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org, 
	d7271.choe@...sung.com, janghyuck.kim@...sung.com, hyesoo.yu@...sung.com
Subject: Re: [BUG] mutex deadlock of dpm_resume() in low memory situation

On Wed, Dec 27, 2023 at 5:08 PM Greg KH <gregkh@...uxfoundation.org> wrote:
>
> On Wed, Dec 27, 2023 at 05:42:50PM +0900, Youngmin Nam wrote:
> > Could you look into this issue ?
>
> Can you submit a patch that resolves the issue for you, as you have a
> way to actually test this out?  That would be the quickest way to get it
> resolved, and to help confirm that this is even an issue at all.

This is a real problem, unfortunately, and the fix would require some
infra changes AFAICS.

To address it, we would need a variant of async_schedule_node_domain()
that would bail out on low memory instead of attempting to run the
stuff synchronously which is harmful (not just for the deadlock
reason) in the suspend-resume paths.

I'll try to cut a test patch shortly.