Prev: Problem with "tcp: bind() fix when many ports are bound" commit
Next: [watchdog] separate touch_nmi_watchdog code path from touch_watchdog
From: Jens Axboe on 28 Apr 2010 13:50
On Wed, Apr 28 2010, Dmitry Monakhov wrote:
> Vivek Goyal <vgoyal(a)redhat.com> writes:
>
> > On Wed, Apr 28, 2010 at 04:44:51PM +0400, Dmitry Monakhov wrote:
> >>
> >> I've had an oops on kernel boot due to NULL pointer deference
> >> linux-2.6-block/for-next HEAD:7eaed1226ab411ee5dc8c34fc0d8034e4c98e3c6
> >> I've enabled CONFIG_BLK_CGROUP, but not CFQ_GROUP_IOSCHED
> >> In this case cfq_ref_get_cfqg() defined as
> >> static inline struct cfq_group *cfq_ref_get_cfqg(struct cfq_group *cfqg)
> >> {
> >> return NULL;
> >> }
> >> So following call trace is simply NOOP
> >> cfq_set_request()
> >> rq->elevator_private3 = cfq_ref_get_cfqg(cfqq->cfqg);
> >>
> >> Which later result in OOPS on bio insertion
> >> cfq_insert_request
> >> -> blkiocg_update_io_add_stats(&(RQ_CFQG(rq))->blkg,...)
> >> -> spin_lock_irqsave(&blkg->stats_lock, flags);
> >>
> >> Bad commit.
> >> >From 7f1dc8a2d2f45fc557b27fd56115338b1d34fc24 Mon Sep 17 00:00:00 2001
> >> From: Vivek Goyal <vgoyal(a)redhat.com>
> >> Date: Wed, 21 Apr 2010 17:44:16 +0200
> >> Subject: [PATCH] blkio: Fix blkio crash during rq stat update
> >
> > Dmitry, this patch should fix the issue. Can you please give it a try.
> Yes. the issue is gone.
> >
> > Jens, I know you don't like this form of cfq_ref_get_cfqg(), but this
> > seems to be the simplest solution to fix it.
> IMHO following fix is simpler, and cleaner.

Agreed, that's much better. I'll add it, thanks.

--
Jens Axboe

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo(a)vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
First  |  Prev  | 
Pages: 1 2
Prev: Problem with "tcp: bind() fix when many ports are bound" commit
Next: [watchdog] separate touch_nmi_watchdog code path from touch_watchdog