Re: [PATCH v4 05/11] mm: do not split a folio if it has minimum folio order requirement

From: Luis Chamberlain <mcgrof@kernel.org>
To: Matthew Wilcox <willy@infradead.org>
Cc: "Pankaj Raghav (Samsung)" <kernel@pankajraghav.com>,
	djwong@kernel.org, brauner@kernel.org, david@fromorbit.com,
	chandan.babu@oracle.com, akpm@linux-foundation.org,
	linux-fsdevel@vger.kernel.org, hare@suse.de,
	linux-kernel@vger.kernel.org, linux-mm@kvack.org,
	linux-xfs@vger.kernel.org, gost.dev@samsung.com,
	p.raghav@samsung.com
Subject: Re: [PATCH v4 05/11] mm: do not split a folio if it has minimum folio order requirement
Date: Fri, 26 Apr 2024 16:46:11 -0700	[thread overview]
Message-ID: <Ziw8w3P9vljrO9JV@bombadil.infradead.org> (raw)
In-Reply-To: <Zir5n6JNiX14VoPm@bombadil.infradead.org>

On Thu, Apr 25, 2024 at 05:47:28PM -0700, Luis Chamberlain wrote:
> On Thu, Apr 25, 2024 at 09:10:16PM +0100, Matthew Wilcox wrote:
> > On Thu, Apr 25, 2024 at 01:37:40PM +0200, Pankaj Raghav (Samsung) wrote:
> > > From: Pankaj Raghav <p.raghav@samsung.com>
> > > 
> > > using that API for LBS is resulting in an NULL ptr dereference
> > > error in the writeback path [1].
> > >
> > > [1] https://gist.github.com/mcgrof/d12f586ec6ebe32b2472b5d634c397df
> > 
> >  How would I go about reproducing this?
> 
> Using kdevops this is easy:
> 
> make defconfig-lbs-xfs-small -j $(nproc)
> make -j $(nproc)

I forgot after the above:

make bringup

> make fstests
> make linux
> make fstests-baseline TESTS=generic/447 COUNT=10
> tail -f guestfs/*-xfs-reflink-16k-4ks/console.log

The above tail command needs sudo prefix for now too.

> or
> sudo virsh list
> sudo virsh console ${foo}-xfs-reflink-16k-4ks
> 
> Where $foo is the value of CONFIG_KDEVOPS_HOSTS_PREFIX in .config for
> your kdevops run.
>
> I didn't have time to verify if the above commands for kdevops worked

I did now, I forgot to git push commits to kdevops yesterday but I
confirm the above steps can be used to repdroduce this issue now.

  Luis