On Thu 24-07-14 15:29:38, Ted Tso wrote: > On Thu, Jul 24, 2014 at 05:27:22PM +0200, Pavel Machek wrote: > > Hi! > > > > Just... I know, I should not be unscrewing hard drive cover while > > operating. > > > > But on the other hand... WARN_ON() does not sound like right reply for > > a disk failure... right? > > Actually, it can be worse than that. If a hard drive disappears out > from under you while writeback is happening, it's possible to get > crashes in bdi_writeack_workfn() because you can have races between > bdi_unregister() and bdi_writeback_workfn(), since the latter requeues > itself and flush_delayed_work() can return while > bdi_writeback_workfn() is still executing. This should be fixed by 5acda9d12dcf1ad0d9a5a2a7c646de3472fa7555 I wrote in April. But there are certainly other races in that code... > This looks like it's a related problem, where the block device gets > unregistered (and this happens in the block device layer without it > telling the file system that the disk drive is about to disappear out > from under it), and occasionally, Bad Stuff Happens. :-( Yeah. Honza -- Jan Kara <jack@xxxxxxx> SUSE Labs, CR -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
