linux-ext4 - Re: probable quota bug introduced in 6.6-rc1

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Message-ID: <20231004150019.j2nebmxoa7zttu4x@quack3>
Date:   Wed, 4 Oct 2023 17:00:19 +0200
From:   Jan Kara <jack@...e.cz>
To:     Eric Whitney <enwlinux@...il.com>
Cc:     linux-ext4@...r.kernel.org, jack@...e.cz, libaokun1@...wei.com,
        linux-fsdevel@...r.kernel.org
Subject: Re: probable quota bug introduced in 6.6-rc1

On Tue 03-10-23 20:11:11, Eric Whitney wrote:
> When run on my test hardware, generic/270 triggers hung task timeouts when
> run on a 6.6-rc1 (or -rc2, -rc3, -rc4) kernel with kvm-xfstests using the
> nojournal test scenario.  The test always passes, but about 60% of the time
> the running time of the test increases by an order of magnitude or more and
> one or more of the hung task timeout warnings included below can be found in
> the log.
> 
> This does not reproduce on 6.5.  Bisection leads to this patch:
> 
> dabc8b207566 ("quota: fix dqput() to follow the guarantees dquot_srcu should
> provide")

Thanks for report! Indeed I can reproduce this. Attached patch fixes the
problem for me, I'll queue it up in my tree once it passes some more
testing.

								Honza
-- 
Jan Kara <jack@...e.com>
SUSE Labs, CR

View attachment "0001-quota-Fix-slow-quotaoff.patch" of type "text/x-patch" (8406 bytes)