Hi Christof, On 2009/02/18 23:21 +0900, Christof Schmitt wrote: > > From: Christof Schmitt <christof.schmitt@xxxxxxxxxx> > > > > Testing with request based dm multipathing and lock dependency checking > > revealed this problem. Fix this by disabling interrupts when acquiring the > > map_lock from the ioctl call in __bind and __unbind. > > > > It seems that the problem has been introduced with this patch: > > http://lkml.indiana.edu/hypermail/linux/kernel/0810.0/1067.html Thank you for your testing request-based dm-multipath and the patch. Attached is a patch to fix it. Since request-based dm gets map_lock after taking queue_lock with interrupt disabled, we have to use save/restore variant. (By the way, although lockdep warns the deadlock possibility, currently there should be no such code path in request-based dm where request_fn is called from the interrupt context.) I have done simple build and boot testings, but haven't done other testings (e.g. stress testing) yet. I will include this patch to the next update after such testings. Thanks, Kiyoshi Ueda Index: linux-2.6.29-rc2/drivers/md/dm.c =================================================================== --- linux-2.6.29-rc2.orig/drivers/md/dm.c +++ linux-2.6.29-rc2/drivers/md/dm.c @@ -504,12 +504,13 @@ static int queue_io(struct mapped_device struct dm_table *dm_get_table(struct mapped_device *md) { struct dm_table *t; + unsigned long flags; - read_lock(&md->map_lock); + read_lock_irqsave(&md->map_lock, flags); t = md->map; if (t) dm_table_get(t); - read_unlock(&md->map_lock); + read_unlock_irqrestore(&md->map_lock, flags); return t; } @@ -1892,6 +1893,7 @@ static int __bind(struct mapped_device * { struct request_queue *q = md->queue; sector_t size; + unsigned long flags; size = dm_table_get_size(t); @@ -1921,10 +1923,10 @@ static int __bind(struct mapped_device * if (dm_table_request_based(t) && !blk_queue_stopped(q)) stop_queue(q); - write_lock(&md->map_lock); + write_lock_irqsave(&md->map_lock, flags); md->map = t; dm_table_set_restrictions(t, q); - write_unlock(&md->map_lock); + write_unlock_irqrestore(&md->map_lock, flags); return 0; } @@ -1932,14 +1934,15 @@ static int __bind(struct mapped_device * static void __unbind(struct mapped_device *md) { struct dm_table *map = md->map; + unsigned long flags; if (!map) return; dm_table_event_callback(map, NULL, NULL); - write_lock(&md->map_lock); + write_lock_irqsave(&md->map_lock, flags); md->map = NULL; - write_unlock(&md->map_lock); + write_unlock_irqrestore(&md->map_lock, flags); dm_table_destroy(map); } -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
