linux-kernel - Re: [PATCH 0/6] power: wire-up filesystem freeze/thaw with suspend/resume

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Message-ID: <20250401-ballen-eulen-8d074cd8ca78@brauner>
Date: Tue, 1 Apr 2025 16:40:33 +0200
From: Christian Brauner <brauner@...nel.org>
To: Peter Zijlstra <peterz@...radead.org>
Cc: linux-fsdevel@...r.kernel.org, jack@...e.cz, rafael@...nel.org, 
	Ard Biesheuvel <ardb@...nel.org>, linux-efi@...r.kernel.org, linux-kernel@...r.kernel.org, 
	James Bottomley <James.Bottomley@...senpartnership.com>, mcgrof@...nel.org, hch@...radead.org, david@...morbit.com, 
	djwong@...nel.org, pavel@...nel.org, mingo@...hat.com, will@...nel.org, 
	boqun.feng@...il.com
Subject: Re: [PATCH 0/6] power: wire-up filesystem freeze/thaw with
 suspend/resume

On Tue, Apr 01, 2025 at 04:14:07PM +0200, Peter Zijlstra wrote:
> On Tue, Apr 01, 2025 at 02:32:45AM +0200, Christian Brauner wrote:
> > The whole shebang can also be found at:
> > https://web.git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs.git/log/?h=work.freeze
> > 
> > I know nothing about power or hibernation. I've tested it as best as I
> > could. Works for me (TM).
> > 
> > I need to catch some actual sleep now...
> > 
> > ---
> > 
> > Now all the pieces are in place to actually allow the power subsystem to
> > freeze/thaw filesystems during suspend/resume. Filesystems are only
> > frozen and thawed if the power subsystem does actually own the freeze.
> 
> Urgh, I was relying on all kthreads to be freezable for live-patching:
> 
>   https://lkml.kernel.org/r/20250324134909.GA14718@noisy.programming.kicks-ass.net
> 
> So I understand the problem with freezing filesystems, but can't we
> leave the TASK_FREEZABLE in the kthreads? The way I understand it, the

Yeah, we can.

> power subsystem will first freeze the filesystems before it goes freeze
> threads anyway. So them remaining freezable should not affect anything,
> right?

Yes. I've dropped the other patches. I've discussed this later
downthread with Jan.
>