On 11/03/2011 05:14 PM, Tejun Heo wrote: > On Thu, Nov 03, 2011 at 05:08:40PM +0100, Jiri Slaby wrote: >> Hi, >> >> I'm seeing the NULL ptr dereference below on each boot of KVM virtual >> machine. q->elevator is NULL. This is next-20111025. >> >> I tried to apply Tejun's patch from: >> https://lkml.org/lkml/2011/4/30/87 >> but it doesn't help. Maybe I should revert something? >> >> Scanning for LVM volume groups... >> Reading all physical volumes. This may take a while... >> No volume groups found >> BUG: unable to handle kernel NULL pointer dereference at (null) >> IP: [<ffffffff8125a69c>] elv_drain_elevator+0x1c/0x70 >> PGD 46176067 PUD 452b5067 PMD 0 >> Oops: 0000 [#1] SMP >> CPU 0 >> Modules linked in: >> >> Pid: 830, comm: kworker/0:2 Not tainted 3.1.0-next-20111025_64+ #1590 >> Bochs Bochs >> RIP: 0010:[<ffffffff8125a69c>] [<ffffffff8125a69c>] >> elv_drain_elevator+0x1c/0x70 > > Heh, probably md is tearing down a queue which isn't fully setup. > Does the following fix the problem? Yes, it does. Thanks a lot. > diff --git a/block/blk-core.c b/block/blk-core.c > index f658711..5292e31 100644 > --- a/block/blk-core.c > +++ b/block/blk-core.c > @@ -408,7 +408,8 @@ void blk_cleanup_queue(struct request_queue *q) > mutex_unlock(&q->sysfs_lock); > > /* drain all requests queued before DEAD marking */ > - blk_drain_queue(q, true); > + if (q->elevator) > + blk_drain_queue(q, true); > > /* @q won't process any more request, flush async actions */ > del_timer_sync(&q->backing_dev_info.laptop_mode_wb_timer); > > -- js suse labs -- 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
