linux-kernel - Re: [PATCH v1] PM: suspend: clean up redundant filesystems

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Message-ID: <CAJZ5v0jKwHZUpsYLzUkcL4=FDnewXoTeJo5e+ccyHw2bZ+ghTg@mail.gmail.com>
Date: Tue, 15 Jul 2025 14:48:24 +0200
From: "Rafael J. Wysocki" <rafael@...nel.org>
To: Zihuan Zhang <zhangzihuan@...inos.cn>
Cc: "Rafael J. Wysocki" <rafael@...nel.org>, Christian Brauner <brauner@...nel.org>, 
	Len Brown <len.brown@...el.com>, Pavel Machek <pavel@...nel.org>, linux-pm@...r.kernel.org, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v1] PM: suspend: clean up redundant filesystems_freeze/thaw
 handling

On Tue, Jul 15, 2025 at 8:12 AM Zihuan Zhang <zhangzihuan@...inos.cn> wrote:
>
> Hi Rafael,
>
> 在 2025/7/15 01:57, Rafael J. Wysocki 写道:
> > Hi,
> >
> > On Mon, Jul 14, 2025 at 10:44 AM Zihuan Zhang <zhangzihuan@...inos.cn> wrote:
> >> Hi Rafael,
> >>
> >> Just a gentle ping on this patch.
> > I've lost track of it for some reason, sorry.
> >
> >> I realized I forgot to mention an important motivation in the changelog:
> >> calling filesystems_freeze() twice (from both suspend_prepare() and
> >> enter_state()) lead to a black screen and make the system unable to resume..
> >>
> >> This patch avoids the duplicate call and resolves that issue.
> > Now applied as a fix for 6.16-rc7, thank you!
>
>
> Thanks for the reply!
>
> Just a quick follow-up question — we noticed that even when the “freeze
> filesystems” feature is not enabled, the current code still calls
> filesystems_thaw().
>
> Do you think it would make sense to guard this with a static key (or
> another mechanism) to avoid unnecessary overhead?

Possibly, if this overhead is significant, but is it?