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	Sat, 08 Feb 2025 10:11:46 +0000
Date: Sat, 8 Feb 2025 10:11:45 +0000
From: Matthew Wilcox <willy@infradead.org>
To: Joanne Koong <joannelkoong@gmail.com>
Cc: Vlastimil Babka <vbabka@suse.cz>, Josef Bacik <josef@toxicpanda.com>,
	Miklos Szeredi <miklos@szeredi.hu>,
	Christian Heusel <christian@heusel.eu>,
	Miklos Szeredi <mszeredi@redhat.com>, regressions@lists.linux.dev,
	linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
	linux-mm <linux-mm@kvack.org>,
	Mantas =?utf-8?Q?Mikul=C4=97nas?= <grawity@gmail.com>
Subject: Re: [REGRESSION][BISECTED] Crash with Bad page state for
 FUSE/Flatpak related applications since v6.13
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On Fri, Feb 07, 2025 at 04:22:56PM -0800, Joanne Koong wrote:
> > Thanks, Josef. I guess we can at least try to confirm we're on the right track.
> > Can anyone affected see if this (only compile tested) patch fixes the issue?
> > Created on top of 6.13.1.
> 
> This fixes the crash for me on 6.14.0-rc1. I ran the repro using
> Mantas's instructions for Obfuscate. I was able to trigger the crash
> on a clean build and then with this patch, I'm not seeing the crash
> anymore.

Since this patch fixes the bug, we're looking for one call to folio_put()
too many.  Is it possibly in fuse_try_move_page()?  In particular, this
one:

        /* Drop ref for ap->pages[] array */
        folio_put(oldfolio);

I don't know fuse very well.  Maybe this isn't it.