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From:   Linus Torvalds <torvalds@linux-foundation.org>
Date:   Thu, 25 Jul 2019 09:32:13 -0700
Message-ID: <CAHk-=wg+yRjY_AUrjbgrN59OeGAWMF_q=-Dqf2cYtVzoY01j7Q@mail.gmail.com>
Subject: Re: [LTP] 56cbb429d9: ltp.fs_fill.fail
To:     Cyril Hrubis <chrubis@suse.cz>
Cc:     kernel test robot <rong.a.chen@intel.com>,
        Al Viro <viro@zeniv.linux.org.uk>, LKP <lkp@01.org>,
        LKML <linux-kernel@vger.kernel.org>, ltp@lists.linux.it
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On Thu, Jul 25, 2019 at 6:26 AM Cyril Hrubis <chrubis@suse.cz> wrote:
>
> This looks like mkfs.vfat got EBUSY after the loop device was
> succesfully umounted.

Hmm. Smells like the RCU-delaying got triggered again.

We have that "synchronize_rcu_expedited()" in namespace_unlock(),
which is so that everything should be done by the time we return to
user space.

Al, maybe that RCU synchronization should be after the mntput()s?

               Linus