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

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Message-ID: <20250402-radstand-neufahrzeuge-198b40c2d073@brauner>
Date: Wed, 2 Apr 2025 09:46:29 +0200
From: Christian Brauner <brauner@...nel.org>
To: James Bottomley <James.Bottomley@...senpartnership.com>
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, 
	mcgrof@...nel.org, hch@...radead.org, david@...morbit.com, djwong@...nel.org, 
	pavel@...nel.org, peterz@...radead.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 01:02:07PM -0400, James Bottomley wrote:
> On Tue, 2025-04-01 at 02:32 +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'm testing the latest you have in work.freeze and it doesn't currently
> work for me.  Patch 7b315c39b67d ("power: freeze filesystems during
> suspend/resume") doesn't set filesystems_freeze_ptr so it ends up being
> NULL and tripping over this check 

I haven't pushed the new version there. Sorry about that. I only have it
locally.

> 
> +static inline bool may_unfreeze(struct super_block *sb, enum
> freeze_holder who,
> +                               const void *freeze_owner)
> +{
> +       WARN_ON_ONCE((who & ~FREEZE_FLAGS));
> +       WARN_ON_ONCE(hweight32(who & FREEZE_HOLDERS) > 1);
> +
> +       if (who & FREEZE_EXCL) {
> +               if (WARN_ON_ONCE(sb->s_writers.freeze_owner == NULL))
> +                       return false;
> 
> 
> in f15a9ae05a71 ("fs: add owner of freeze/thaw") and failing to resume
> from hibernate.  Setting it to __builtin_return_address(0) in
> filesystems_freeze() makes everything work as expected, so that's what
> I'm testing now.

+1

I'll send the final version out in a bit.