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Subject: Re: [powerpc][5.13.0-next-20210701] Kernel crash while running
 ltp(chdir01) tests
From:   Sachin Sant <sachinp@linux.vnet.ibm.com>
In-Reply-To: <YOG/5ZY1AL05jumi@mit.edu>
Date:   Mon, 5 Jul 2021 16:57:26 +0530
Cc:     Zhang Yi <yi.zhang@huawei.com>, Jan Kara <jack@suse.cz>,
        linuxppc-dev@lists.ozlabs.org,
        Guoqing Jiang <guoqing.jiang@linux.dev>,
        Ext4 Developers List <linux-ext4@vger.kernel.org>,
        "linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>
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References: <26ACA75D-E13D-405B-9BFC-691B5FB64243@linux.vnet.ibm.com>
 <bf1c5b38-92f1-65db-e210-a97a199718ba@linux.dev>
 <4cc87ab3-aaa6-ed87-b690-5e5b99de8380@huawei.com>
 <03f734bd-f36e-f55b-0448-485b8a0d5b75@huawei.com> <YN86yl5kgVaRixxQ@mit.edu>
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 <66fb56cd-f1ff-c592-0202-0691372e32f5@huawei.com> <YOG/5ZY1AL05jumi@mit.edu>
To:     "Theodore Ts'o" <tytso@mit.edu>
Precedence: bulk


> On 04-Jul-2021, at 7:34 PM, Theodore Ts'o <tytso@mit.edu> wrote:
>=20
> On Sat, Jul 03, 2021 at 12:55:09PM +0800, Zhang Yi wrote:
>> Yeah, it sounds good to me. Do you want me to send the fix patch, or =
you
>> modify your commit 8f9e16badb8fd in another email directly?
>=20
> I've gone ahead and made the changes; what do you think?
>=20
> I like how it also removes 40 lines of code.  :-)
>=20
>     	  	    	     	      	   - Ted
>=20
> =46rom ef3130d1b0b8ca769252d6a722a2e59a00141383 Mon Sep 17 00:00:00 =
2001
> From: Theodore Ts'o <tytso@mit.edu>
> Date: Fri, 2 Jul 2021 18:05:03 -0400
> Subject: [PATCH] ext4: inline jbd2_journal_[un]register_shrinker()
>=20
> The function jbd2_journal_unregister_shrinker() was getting called
> twice when the file system was getting unmounted.  On Power and ARM
> platforms this was causing kernel crash when unmounting the file
> system, when a percpu_counter was destroyed twice.
>=20
> Fix this by removing jbd2_journal_[un]register_shrinker() functions,
> and inlining the shrinker setup and teardown into
> journal_init_common() and jbd2_journal_destroy().  This means that
> ext4 and ocfs2 now no longer need to know about registering and
> unregistering jbd2's shrinker.
>=20
> Also, while we're at it, rename the percpu counter from
> j_jh_shrink_count to j_checkpoint_jh_count, since this makes it
> clearer what this counter is intended to track.
>=20
> Fixes: 4ba3fcdde7e3 ("jbd2,ext4: add a shrinker to release =
checkpointed buffers")
> Reported-by: Sachin Sant <sachinp@linux.vnet.ibm.com>
> Reported-by: Jon Hunter <jonathanh@nvidia.com>
> Signed-off-by: Theodore Ts'o <tytso@mit.edu>
> ---

This patch fixes the reported problem. Test ran to completion
without any crash.

Tested-by: Sachin Sant <sachinp@linux.vnet.ibm.com>

-Sachin