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From: Al Viro <viro@ZenIV.linux.org.uk>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Matthew Wilcox <matthew@wil.cx>,
	LKML <linux-kernel@vger.kernel.org>,
	linux-fsdevel@vger.kernel.org,
	Stephen Smalley <sds@tycho.nsa.gov>,
	Christoph Hellwig <hch@infradead.org>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Eric Paris <eparis@parisplace.org>, Theodore Ts'o <tytso@mit.edu>,
	Dave Chinner <david@fromorbit.com>,
	James Morris <james.l.morris@oracle.com>,
	Paul Moore <paul@paul-moore.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
	stable <stable@vger.kernel.org>
Subject: Re: [PATCH] vfs: Fix possible NULL pointer dereference in inode_permission()
Date: Thu, 9 Jan 2014 22:31:27 +0000	[thread overview]
Message-ID: <20140109223127.GM10323@ZenIV.linux.org.uk> (raw)
In-Reply-To: <20140109165012.391db81e@gandalf.local.home>

On Thu, Jan 09, 2014 at 04:50:12PM -0500, Steven Rostedt wrote:

> > We'd then have to get rid of all the call_rcu() invocations in individual
> > filesystems' destroy_inode methods, but that doesn't sound like a bad
> > thing to me.

Check what e.g. XFS is doing...

> Which is another reason that I didn't do it, as I didn't know all the
> happenings inside the ->destroy_inode() calls. But yeah, I agree with
> this.
> 
> Also, can iput() sleep? If not then we are OK. Otherwise, we need to be
> careful about any mutex being grabbed in those call backs, as the
> rcu_callback can't sleep either.

iput() definitely can sleep (that's when actual truncation and inode
freeing is done for opened-and-unlinked files - on the final iput() after
close()), but that' irrelevant here - fsnotify_delete_inode() grabs
a bunch of mutexes, which makes calling it from rcu callback no-go.

  reply	other threads:[~2014-01-09 22:31 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-01-09 21:27 [PATCH] vfs: Fix possible NULL pointer dereference in inode_permission() Steven Rostedt
2014-01-09 21:42 ` Matthew Wilcox
2014-01-09 21:50   ` Steven Rostedt
2014-01-09 22:31     ` Al Viro [this message]
     [not found]       ` <CA+55aFzCTPYEQCPnLBi1CwmMTocVqCFiCuJ391HkVx1CMw61ug@mail.gmail.com>
2014-01-09 23:10         ` Paul E. McKenney
2014-01-09 23:25         ` Steven Rostedt
2014-01-09 23:27           ` Steven Rostedt
2014-01-09 23:37             ` Eric Paris
2014-01-09 23:45               ` Steven Rostedt
2014-01-09 23:53               ` Linus Torvalds
2014-01-10  0:06                 ` Al Viro
2014-01-10  0:09                   ` Al Viro
2014-01-10  0:18                   ` Linus Torvalds
2014-01-10  2:36                     ` James Morris
2014-01-10  9:31                   ` Christoph Hellwig
2014-01-10 18:14                     ` Ben Myers
2014-01-11 10:32                       ` Christoph Hellwig
2014-01-09 23:45             ` Paul E. McKenney
2014-01-09 23:59               ` Steven Rostedt
2014-01-10  0:44                 ` Paul E. McKenney

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