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Date: Wed, 16 Apr 2025 13:21:26 -0700
From: "Darrick J. Wong" <djwong@kernel.org>
To: Matthew Wilcox <willy@infradead.org>
Cc: linux-fsdevel <linux-fsdevel@vger.kernel.org>,
	linux-xfs@vger.kernel.org
Subject: Re: [6.15-rc2 regression] iomap: null pointer in a bio completion
Message-ID: <20250416202126.GD25659@frogsfrogsfrogs>
References: <20250416180837.GN25675@frogsfrogsfrogs>
 <Z__5LOpee2-5rIaE@casper.infradead.org>
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In-Reply-To: <Z__5LOpee2-5rIaE@casper.infradead.org>

On Wed, Apr 16, 2025 at 07:38:36PM +0100, Matthew Wilcox wrote:
> On Wed, Apr 16, 2025 at 11:08:37AM -0700, Darrick J. Wong wrote:
> > Hi folks,
> > 
> > I upgraded my arm64 kernel to 6.15-rc2, and I also see this splat in
> > generic/363.  The fstets config is as follows:
> > 
> > MKFS_OPTIONS="-m metadir=1,autofsck=1,uquota,gquota,pquota, -b size=65536,"
> > MOUNT_OPTIONS=""
> > 
> > The VM is arm64 with 64k base pages.  I've disabled LBS to work around
> > a fair number of other strange bugs.  Does this ring a bell for anyone?
> > 
> > --D
> > 
> > list_add double add: new=ffffffff40538c88, prev=fffffc03febf8148, next=ffffffff40538c88.
> 
> Not a bell, but it's weird.  We're trying to add ffffffff40538c88 to
> the list, but next already has that value.  So this is a double-free of
> the folio?  Do you have VM_BUG_ON_FOLIO enabled with CONFIG_VM_DEBUG?

Nope, but I can go re-add it to my kconfig and see what happens.

--D