* CFQ is broken for CONFIG_BLK_CGROUP=y, CFQ_GROUP_IOSCHED=n
@ 2010-04-28 12:44 Dmitry Monakhov
2010-04-28 13:48 ` Vivek Goyal
2010-04-28 15:09 ` Vivek Goyal
0 siblings, 2 replies; 6+ messages in thread
From: Dmitry Monakhov @ 2010-04-28 12:44 UTC (permalink / raw)
To: linux-kernel; +Cc: jens.axboe, Vivek Goyal
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@redhat.com>
Date: Wed, 21 Apr 2010 17:44:16 +0200
Subject: [PATCH] blkio: Fix blkio crash during rq stat update
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: CFQ is broken for CONFIG_BLK_CGROUP=y, CFQ_GROUP_IOSCHED=n 2010-04-28 12:44 CFQ is broken for CONFIG_BLK_CGROUP=y, CFQ_GROUP_IOSCHED=n Dmitry Monakhov @ 2010-04-28 13:48 ` Vivek Goyal 2010-04-28 15:09 ` Vivek Goyal 1 sibling, 0 replies; 6+ messages in thread From: Vivek Goyal @ 2010-04-28 13:48 UTC (permalink / raw) To: Dmitry Monakhov; +Cc: linux-kernel, jens.axboe 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@redhat.com> > Date: Wed, 21 Apr 2010 17:44:16 +0200 > Subject: [PATCH] blkio: Fix blkio crash during rq stat update Hi Dmitry, Thanks for reporting the issue. I am cooking up a patch now. Vivek ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: CFQ is broken for CONFIG_BLK_CGROUP=y, CFQ_GROUP_IOSCHED=n 2010-04-28 12:44 CFQ is broken for CONFIG_BLK_CGROUP=y, CFQ_GROUP_IOSCHED=n Dmitry Monakhov 2010-04-28 13:48 ` Vivek Goyal @ 2010-04-28 15:09 ` Vivek Goyal 2010-04-28 15:36 ` Dmitry Monakhov 1 sibling, 1 reply; 6+ messages in thread From: Vivek Goyal @ 2010-04-28 15:09 UTC (permalink / raw) To: Dmitry Monakhov; +Cc: linux-kernel, jens.axboe 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@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. 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. cfq-iosched: fix cfq crash with CFQ_GROUP_IOSCHED=n Dmitry reported an oops with CFQ when booted with BLK_CGROUP=y and CFQ_GROUP_IOSCHED=n. This patch fixes it. We maintain a root group even if group ioscheduling is not enabled. Hence don't store NULL in elevator_private3 in that case. Signed-off-by: Vivek Goyal <vgoyal@redhat.com> --- block/cfq-iosched.c | 11 ++++------- 1 files changed, 4 insertions(+), 7 deletions(-) diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c index 286008c..5aa5364 100644 --- a/block/cfq-iosched.c +++ b/block/cfq-iosched.c @@ -1002,10 +1002,9 @@ static struct cfq_group *cfq_get_cfqg(struct cfq_data *cfqd, int create) return cfqg; } -static inline struct cfq_group *cfq_ref_get_cfqg(struct cfq_group *cfqg) +static inline void cfq_ref_get_cfqg(struct cfq_group *cfqg) { atomic_inc(&cfqg->ref); - return cfqg; } static void cfq_link_cfqq_cfqg(struct cfq_queue *cfqq, struct cfq_group *cfqg) @@ -1092,10 +1091,7 @@ static struct cfq_group *cfq_get_cfqg(struct cfq_data *cfqd, int create) return &cfqd->root_group; } -static inline struct cfq_group *cfq_ref_get_cfqg(struct cfq_group *cfqg) -{ - return NULL; -} +static inline void cfq_ref_get_cfqg(struct cfq_group *cfqg) {} static inline void cfq_link_cfqq_cfqg(struct cfq_queue *cfqq, struct cfq_group *cfqg) { @@ -3574,7 +3570,8 @@ new_queue: rq->elevator_private = cic; rq->elevator_private2 = cfqq; - rq->elevator_private3 = cfq_ref_get_cfqg(cfqq->cfqg); + rq->elevator_private3 = cfqq->cfqg; + cfq_ref_get_cfqg(cfqq->cfqg); return 0; queue_fail: -- 1.6.2.5 ^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: CFQ is broken for CONFIG_BLK_CGROUP=y, CFQ_GROUP_IOSCHED=n 2010-04-28 15:09 ` Vivek Goyal @ 2010-04-28 15:36 ` Dmitry Monakhov 2010-04-28 15:44 ` Vivek Goyal 2010-04-28 17:43 ` Jens Axboe 0 siblings, 2 replies; 6+ messages in thread From: Dmitry Monakhov @ 2010-04-28 15:36 UTC (permalink / raw) To: Vivek Goyal; +Cc: linux-kernel, jens.axboe [-- Attachment #1: Type: text/plain, Size: 1285 bytes --] Vivek Goyal <vgoyal@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@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. [-- Attachment #2: diff --] [-- Type: text/plain, Size: 366 bytes --] diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c index 286008c..0f3eb70 100644 --- a/block/cfq-iosched.c +++ b/block/cfq-iosched.c @@ -1094,7 +1094,7 @@ static struct cfq_group *cfq_get_cfqg(struct cfq_data *cfqd, int create) static inline struct cfq_group *cfq_ref_get_cfqg(struct cfq_group *cfqg) { - return NULL; + return cfqg; } static inline void ^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: CFQ is broken for CONFIG_BLK_CGROUP=y, CFQ_GROUP_IOSCHED=n 2010-04-28 15:36 ` Dmitry Monakhov @ 2010-04-28 15:44 ` Vivek Goyal 2010-04-28 17:43 ` Jens Axboe 1 sibling, 0 replies; 6+ messages in thread From: Vivek Goyal @ 2010-04-28 15:44 UTC (permalink / raw) To: Dmitry Monakhov; +Cc: linux-kernel, jens.axboe On Wed, Apr 28, 2010 at 07:36:02PM +0400, Dmitry Monakhov wrote: > Vivek Goyal <vgoyal@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@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. > diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c > index 286008c..0f3eb70 100644 > --- a/block/cfq-iosched.c > +++ b/block/cfq-iosched.c > @@ -1094,7 +1094,7 @@ static struct cfq_group *cfq_get_cfqg(struct cfq_data *cfqd, int create) > > static inline struct cfq_group *cfq_ref_get_cfqg(struct cfq_group *cfqg) > { > - return NULL; > + return cfqg; > } Thanks Dmitry. I like it. simpler. Vivek ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: CFQ is broken for CONFIG_BLK_CGROUP=y, CFQ_GROUP_IOSCHED=n 2010-04-28 15:36 ` Dmitry Monakhov 2010-04-28 15:44 ` Vivek Goyal @ 2010-04-28 17:43 ` Jens Axboe 1 sibling, 0 replies; 6+ messages in thread From: Jens Axboe @ 2010-04-28 17:43 UTC (permalink / raw) To: Dmitry Monakhov; +Cc: Vivek Goyal, linux-kernel On Wed, Apr 28 2010, Dmitry Monakhov wrote: > Vivek Goyal <vgoyal@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@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 ^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2010-04-28 17:43 UTC | newest] Thread overview: 6+ messages (download: mbox.gz follow: Atom feed -- links below jump to the message on this page -- 2010-04-28 12:44 CFQ is broken for CONFIG_BLK_CGROUP=y, CFQ_GROUP_IOSCHED=n Dmitry Monakhov 2010-04-28 13:48 ` Vivek Goyal 2010-04-28 15:09 ` Vivek Goyal 2010-04-28 15:36 ` Dmitry Monakhov 2010-04-28 15:44 ` Vivek Goyal 2010-04-28 17:43 ` Jens Axboe
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