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From: Al Viro <viro@zeniv.linux.org.uk>
To: ltp@lists.linux.it
Subject: [LTP] 56cbb429d9: ltp.fs_fill.fail
Date: Thu, 25 Jul 2019 19:04:28 +0100	[thread overview]
Message-ID: <20190725180428.GH1131@ZenIV.linux.org.uk> (raw)
In-Reply-To: <CAHk-=wg+yRjY_AUrjbgrN59OeGAWMF_q=-Dqf2cYtVzoY01j7Q@mail.gmail.com>

On Thu, Jul 25, 2019 at 09:32:13AM -0700, Linus Torvalds wrote:
> 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?

There are several interesting issues in there, but synchronize_rcu()
should be between zeroing ->mnt_ns and dropping the final refs.
I'm digging through that crap right now; at least one bug is dealt
with by #fixes, but there's more, unfortunately.

  reply	other threads:[~2019-07-25 18:04 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-07-25 11:09 [LTP] 56cbb429d9: ltp.fs_fill.fail kernel test robot
2019-07-25 13:26 ` Cyril Hrubis
2019-07-25 16:32   ` Linus Torvalds
2019-07-25 18:04     ` Al Viro [this message]
2019-07-26  0:00       ` Al Viro

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