On Thu, 2011-09-22 at 14:26 +0200, Hannes Reinecke wrote: > On 09/20/2011 09:32 AM, Jun'ichi Nomura wrote: > > On 09/19/11 08:00, Ben Hutchings wrote: > [ .. ] > >> > >> There have been reports of this in Debian going back to 2.6.39: > >> > >> http://bugs.debian.org/631187 > >> http://bugs.debian.org/636263 > >> http://bugs.debian.org/642043 > >> > >> Plus possibly related crashes in elv_put_request after CD-ROM removal: > >> > >> http://bugs.debian.org/633890 > >> http://bugs.debian.org/634681 > >> http://bugs.debian.org/636103 > >> > >> The former was also reported in Ubuntu since their 2.6.38-10: > >> > >> https://bugs.launchpad.net/debian/+source/linux-2.6/+bug/793796 > >> > >> The result of the discussion there was that it appeared to be a > >> regression due to commit 86cbfb5607d4b81b1a993ff689bbd2addd5d3a9b > >> ("[SCSI] put stricter guards on queue dead checks") which was also > >> included in a stable update for 2.6.38. > >> > >> There was also a report on bugzilla.kernel.org, though no-one can see > >> quite what that says now: > >> > >> https://bugzilla.kernel.org/show_bug.cgi?id=38842 > >> > >> I also reported most of the above to James Bottomley and linux-scsi > >> nearly 2 months ago, to no response. > > > > I've reported a similar oops related to the above commit: > > [BUG] Oops when SCSI device under multipath is removed > > https://lkml.org/lkml/2011/8/10/11 > > > > Elevator being removed is the core of the problem. > > And the essential issue seems 2 different models of queue/driver relation > > implied by queue_lock. > > > > If reverting the commit is not an option, > > until somebody comes up to fix the essential issue, > > the patch below should close the regressions introduced by the commit. > > > Why do you have to do it that complicated? > Couldn't we just state that any external lock is being disconnected from > queue_lock after blk_cleanup_queue()? > > Then something like this should suffice here: > > diff --git a/block/blk-core.c b/block/blk-core.c > index 90e1ffd..a4ac005 100644 > --- a/block/blk-core.c > +++ b/block/blk-core.c > @@ -367,10 +367,8 @@ void blk_cleanup_queue(struct request_queue *q) > queue_flag_set_unlocked(QUEUE_FLAG_DEAD, q); > mutex_unlock(&q->sysfs_lock); > > - if (q->elevator) > - elevator_exit(q->elevator); > - > - blk_throtl_exit(q); > + if (q->queue_lock != q->__queue_lock) > + q->queue_lock = q->__queue_lock; > > blk_put_queue(q); > } > diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c > index 0ee17b5..a5a756b 100644 > --- a/block/blk-sysfs.c > +++ b/block/blk-sysfs.c > @@ -477,6 +477,11 @@ static void blk_release_queue(struct kobject *kobj) > > blk_sync_queue(q); > > + if (q->elevator) > + elevator_exit(q->elevator); > + > + blk_throtl_exit(q); > + OK, I'll buy this one (when you fix the whitespace issue ... you have spaces instead of tabs). The fact that the lock check/replacement doesn't actually need any locking is probably worthy of a comment. James -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
