Re: [PATCH] mmotm: fix hang at startup
From: Wu Fengguang <hidden>
Date: 2011-05-01 03:25:07
Also in:
linux-fsdevel, lkml
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 <hughd@google.com>
Thanks! Reviewed-by: Wu Fengguang <redacted>
quoted hunk ↗ jump to hunk
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;
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