From mboxrd@z Thu Jan 1 00:00:00 1970 From: Wu Fengguang Subject: Re: [PATCH] mmotm: fix hang at startup Date: Sun, 1 May 2011 11:25:07 +0800 Message-ID: <20110501032507.GA21118@localhost> References: <201104300002.p3U02Ma2026266@imap1.linux-foundation.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Andrew Morton , Christoph Hellwig , "linux-kernel@vger.kernel.org" , "linux-mm@kvack.org" , "linux-fsdevel@vger.kernel.org" To: Hugh Dickins Return-path: Content-Disposition: inline In-Reply-To: Sender: owner-linux-mm@kvack.org List-Id: linux-fsdevel.vger.kernel.org On Sun, May 01, 2011 at 10:35:38AM +0800, Hugh Dickins wrote: > Yesterday's mmotm hangs at startup, and with lockdep it reports: > BUG: spinlock recursion on CPU#1, blkid/284 - with bdi_lock_two() > called from bdev_inode_switch_bdi() in the backtrace. It appears > that this function is sometimes called with new the same as old. > > Signed-off-by: Hugh Dickins Thanks! Reviewed-by: Wu Fengguang > Fix to > writeback-split-inode_wb_list_lock-into-bdi_writebacklist_lock.patch > > fs/block_dev.c | 2 ++ > 1 file changed, 2 insertions(+) > > --- 2.6.39-rc5-mm1/fs/block_dev.c 2011-04-29 18:20:09.183314733 -0700 > +++ linux/fs/block_dev.c 2011-04-30 17:55:45.718785263 -0700 > @@ -57,6 +57,8 @@ static void bdev_inode_switch_bdi(struct > { > struct backing_dev_info *old = inode->i_data.backing_dev_info; > > + if (dst == old) > + return; nitpick: it could help to add a comment /* avoid spinlock recursion */ to indicate that's not merely an optional optimization, but indeed required for correctness. Thanks, Fengguang > bdi_lock_two(&old->wb, &dst->wb); > spin_lock(&inode->i_lock); > inode->i_data.backing_dev_info = dst; -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org