From: Ted Ts'o <tytso@mit.edu>
To: Minchan Kim <minchan.kim@gmail.com>
Cc: linux-ext4@vger.kernel.org, linux-mm@kvack.org,
linux-kernel@vger.kernel.org,
Andreas Dilger <adilger.kernel@dilger.ca>,
Paul McKenney <paulmck@linux.vnet.ibm.com>,
Eric Sandeen <sandeen@redhat.com>
Subject: Re: [BUG?] [Ext4] INFO: suspicious rcu_dereference_check() usage
Date: Sun, 21 Nov 2010 12:37:26 -0500 [thread overview]
Message-ID: <20101121173726.GG23423@thunk.org> (raw)
In-Reply-To: <20101121153949.GD20947@barrios-desktop>
On Mon, Nov 22, 2010 at 12:39:49AM +0900, Minchan Kim wrote:
>
> I think it's no problem.
>
> That's because migration always holds lock_page on the file page.
> So the page couldn't remove from radix.
It may be "ok" in that it won't cause a race, but it still leaves an
unsightly warning if LOCKDEP is enabled, and LOCKDEP warnings will
cause /proc_lock_stat to be disabled. So I think it still needs to be
fixed by adding rcu_read_lock()/rcu_read_unlock() to
migrate_page_move_mapping().
- Ted
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WARNING: multiple messages have this Message-ID (diff)
From: "Ted Ts'o" <tytso@mit.edu>
To: Minchan Kim <minchan.kim@gmail.com>
Cc: linux-ext4@vger.kernel.org, linux-mm@kvack.org,
linux-kernel@vger.kernel.org,
Andreas Dilger <adilger.kernel@dilger.ca>,
Paul McKenney <paulmck@linux.vnet.ibm.com>,
Eric Sandeen <sandeen@redhat.com>
Subject: Re: [BUG?] [Ext4] INFO: suspicious rcu_dereference_check() usage
Date: Sun, 21 Nov 2010 12:37:26 -0500 [thread overview]
Message-ID: <20101121173726.GG23423@thunk.org> (raw)
In-Reply-To: <20101121153949.GD20947@barrios-desktop>
On Mon, Nov 22, 2010 at 12:39:49AM +0900, Minchan Kim wrote:
>
> I think it's no problem.
>
> That's because migration always holds lock_page on the file page.
> So the page couldn't remove from radix.
It may be "ok" in that it won't cause a race, but it still leaves an
unsightly warning if LOCKDEP is enabled, and LOCKDEP warnings will
cause /proc_lock_stat to be disabled. So I think it still needs to be
fixed by adding rcu_read_lock()/rcu_read_unlock() to
migrate_page_move_mapping().
- Ted
next prev parent reply other threads:[~2010-11-21 17:37 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-11-21 11:26 [BUG?] [Ext4] INFO: suspicious rcu_dereference_check() usage Arun Bhanu
2010-11-21 13:30 ` Ted Ts'o
2010-11-21 13:30 ` Ted Ts'o
2010-11-21 13:30 ` Ted Ts'o
2010-11-21 15:39 ` Minchan Kim
2010-11-21 15:39 ` Minchan Kim
2010-11-21 15:39 ` Minchan Kim
2010-11-21 17:37 ` Ted Ts'o [this message]
2010-11-21 17:37 ` Ted Ts'o
2010-11-22 0:38 ` Minchan Kim
2010-11-22 0:38 ` Minchan Kim
2010-11-22 0:38 ` Minchan Kim
2010-11-22 3:31 ` Milton Miller
2010-11-22 6:16 ` Paul E. McKenney
2010-12-07 19:01 ` [BUG?] memory hotplug: include/linux/radix-tree.h:145 invoked rcu_dereference_check() without protection! Gerald Schaefer
2010-12-08 1:19 ` KAMEZAWA Hiroyuki
2010-12-16 13:50 ` Gerald Schaefer
2010-12-17 0:04 ` Minchan Kim
2010-12-17 0:04 ` Minchan Kim
2010-12-17 5:47 ` Paul E. McKenney
2010-12-17 5:47 ` Paul E. McKenney
2010-12-17 5:59 ` Eric Dumazet
2010-12-17 5:59 ` Eric Dumazet
2010-12-17 15:08 ` Minchan Kim
2010-12-17 16:03 ` Paul E. McKenney
2010-12-17 16:03 ` Paul E. McKenney
2010-12-17 8:39 ` Mel Gorman
2010-12-17 8:39 ` Mel Gorman
2010-12-17 9:28 ` Mel Gorman
2010-12-17 15:22 ` Minchan Kim
2010-12-17 15:13 ` Minchan Kim
2010-12-17 15:13 ` Minchan Kim
2010-12-17 16:01 ` Paul E. McKenney
2010-12-17 16:01 ` Paul E. McKenney
2010-11-23 7:16 ` [BUG?] [Ext4] INFO: suspicious rcu_dereference_check() usage KOSAKI Motohiro
2010-11-23 7:16 ` KOSAKI Motohiro
2010-11-23 7:16 ` KOSAKI Motohiro
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