From: Al Viro <viro@ZenIV.linux.org.uk>
To: Ian Kent <raven@themaw.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
"J. Bruce Fields" <bfields@fieldses.org>,
linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org
Subject: Re: [RFC] freeing unlinked file indefinitely delayed
Date: Sun, 12 Jul 2015 16:17:29 +0100 [thread overview]
Message-ID: <20150712151729.GK17109@ZenIV.linux.org.uk> (raw)
In-Reply-To: <1436441204.2709.10.camel@pluto.fritz.box>
On Thu, Jul 09, 2015 at 07:26:44PM +0800, Ian Kent wrote:
> > But the dentrys that will most likely face summary execution will be
> > hashed, such as was the case on that 2.6.32 kernel at dput().
> >
> > Doesn't that mean that something dropped the dentry after the dput(),
> > that will now also free the dentry, that took the refcount to 0?
>
> Oh wait, think I get it now ... perhaps it's prune_one_dentry() doing
> it ...
What, unhashing? Yes, it does.
A bit of context - the breakage that had first pointed in direction of
this bug had been a deadlock with dcache shrinker run on frozen fs was
stumbling across a hashed dentry with zero refcount *and* zero link count
of its inode, triggering its eviction, final iput(), inode freeing and
deadlock on attempt to do sb_start_intwrite() there; figuring out how could
such a dentry appear in the first place had uncovered this fun. Which
a) is a bug in its own right and
b) happens in mainline as well.
next prev parent reply other threads:[~2015-07-12 15:17 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-07-08 1:42 [RFC] freeing unliked file indefinitely delayed Al Viro
2015-07-08 2:39 ` J. Bruce Fields
2015-07-08 15:41 ` Ben Myers
2015-07-12 15:00 ` [RFC] freeing unlinked " Al Viro
2015-07-13 18:17 ` Ben Myers
2015-07-13 19:56 ` Al Viro
2015-07-14 0:54 ` Ben Myers
2015-07-09 11:17 ` [RFC] freeing unliked " Ian Kent
2015-07-09 11:26 ` Ian Kent
2015-07-12 15:17 ` Al Viro [this message]
2015-07-13 2:30 ` [RFC] freeing unlinked " Ian Kent
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