linux-kernel - Re: [PATCH 1/2] PM: runtime: Fix I/O hang due to race between resume and runtime disable

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Message-ID: <CAJZ5v0hJw0WdHpqgUc5bz5qCSUNNKHg7i5-sNYeZcDYwRj21qw@mail.gmail.com>
Date: Wed, 26 Nov 2025 16:41:24 +0100
From: "Rafael J. Wysocki" <rafael@...nel.org>
To: Bart Van Assche <bvanassche@....org>
Cc: "Rafael J. Wysocki" <rafael@...nel.org>, YangYang <yang.yang@...o.com>, Jens Axboe <axboe@...nel.dk>, 
	Pavel Machek <pavel@...nel.org>, Len Brown <lenb@...nel.org>, 
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>, Danilo Krummrich <dakr@...nel.org>, 
	linux-block@...r.kernel.org, linux-kernel@...r.kernel.org, 
	linux-pm@...r.kernel.org
Subject: Re: [PATCH 1/2] PM: runtime: Fix I/O hang due to race between resume
 and runtime disable

On Wed, Nov 26, 2025 at 4:34 PM Bart Van Assche <bvanassche@....org> wrote:
>
> On 11/26/25 4:36 AM, Rafael J. Wysocki wrote:
> > Well, the code as is now schedules an async resume of the device and
> > then waits for it to complete.  It would be more straightforward to
> > resume the device synchronously IMV.
>
> That would increase the depth of the call stack significantly. I'm not
> sure that's safe in this context.

As it stands, you have a basic problem with respect to system
suspend/hibernation.  As I said before, the PM workqueue is frozen
during system suspend/hibernation transitions, so waiting for an async
resume request to complete then is pointless.