From: Al Viro <viro@zeniv.linux.org.uk>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Cyril Hrubis <chrubis@suse.cz>,
kernel test robot <rong.a.chen@intel.com>, LKP <lkp@01.org>,
LKML <linux-kernel@vger.kernel.org>,
ltp@lists.linux.it
Subject: Re: [LTP] 56cbb429d9: ltp.fs_fill.fail
Date: Fri, 26 Jul 2019 01:00:32 +0100 [thread overview]
Message-ID: <20190726000032.GK1131@ZenIV.linux.org.uk> (raw)
In-Reply-To: <20190725180428.GH1131@ZenIV.linux.org.uk>
On Thu, Jul 25, 2019 at 07:04:28PM +0100, Al Viro wrote:
> 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.
No, it's not synchronize_rcu(). It's a bug dealt with in vfs.git #fixes,
triggering the struct mount leak in mount_subtree(), which is used
by btrfs. Immediately prior to vfat in their list...
(oh, and AFAICS "more" in the above had been a mismerge in -next, so
it might really be all there is to it)
Folks, see if vfs.git #fixes solves that one.
prev parent reply other threads:[~2019-07-26 0:00 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-25 11:09 56cbb429d9: ltp.fs_fill.fail kernel test robot
2019-07-25 13:26 ` [LTP] " Cyril Hrubis
2019-07-25 16:32 ` Linus Torvalds
2019-07-25 18:04 ` Al Viro
2019-07-26 0:00 ` Al Viro [this message]
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