3.5.0-rc3 - Issue with CFQ and cgroup

3.5.0-rc3 - Issue with CFQ and cgroup

[Paul Rolland]

Hello,

When I first booted my 3.5.0-rc3 config, I've some :
Default I/O scheduler not found. Using noop.
which surprised me. so, after the boot completed, I had a look at the
system messages, and found :

...
io scheduler noop registered
io scheduler deadline registered
------------[ cut here ]------------
WARNING: at block/blk-cgroup.c:867 blkcg_policy_register+0xb5/0xc0()
Hardware name: Vostro 1520
Modules linked in:
Pid: 1, comm: swapper/0 Not tainted 3.5.0-rc3 #1
Call Trace:
 [<ffffffff8103a59a>] warn_slowpath_common+0x7a/0xb0
 [<ffffffff81cafbed>] ? deadline_init+0x12/0x12
 [<ffffffff8103a5e5>] warn_slowpath_null+0x15/0x20
 [<ffffffff8131a6f5>] blkcg_policy_register+0xb5/0xc0
 [<ffffffff81cafc2f>] cfq_init+0x42/0x9f
 [<ffffffff810001ba>] do_one_initcall+0x3a/0x160
 [<ffffffff81c8ed08>] kernel_init+0x137/0x1bb
 [<ffffffff81c8e5c5>] ? do_early_param+0x87/0x87
 [<ffffffff8169e3d4>] kernel_thread_helper+0x4/0x10
 [<ffffffff81c8ebd1>] ? start_kernel+0x3b2/0x3b2
 [<ffffffff8169e3d0>] ? gs_change+0xb/0xb
---[ end trace 82bc55f036371117 ]---

So, at the time cfq should have registered, something went wrong.
It looks that this comes from my config defining CFQ, CGROUP but no
CFQ_CGROUP_IOSCHED.
...
CONFIG_CGROUPS=y
CONFIG_IOSCHED_CFQ=y
# CONFIG_CFQ_GROUP_IOSCHED is not set
...

as the code is :
static struct blkcg_policy blkcg_policy_cfq __maybe_unused;
...
#ifdef CONFIG_CFQ_GROUP_IOSCHED
static struct blkcg_policy blkcg_policy_cfq = {
        .pd_size                = sizeof(struct cfq_group),
        .cftypes                = cfq_blkcg_files,
        
        .pd_init_fn             = cfq_pd_init,
        .pd_reset_stats_fn      = cfq_pd_reset_stats,
};
#endif
...
static int __init cfq_init(void)
{
...
        ret = blkcg_policy_register(&blkcg_policy_cfq);


Not sure what's the best fix is... Could someone shed some light on this ?

Paul

PS: Just checked 3.5-rc4, source code there is the same.

Re: 3.5.0-rc3 - Issue with CFQ and cgroup

[Tejun Heo]

Hello,

On Wed, Jun 27, 2012 at 07:58:08PM +0200, Paul Rolland wrote:
> Hello,
> 
> When I first booted my 3.5.0-rc3 config, I've some :
> Default I/O scheduler not found. Using noop.
> which surprised me. so, after the boot completed, I had a look at the
> system messages, and found :
> 
> ...
> io scheduler noop registered
> io scheduler deadline registered
> ------------[ cut here ]------------
> WARNING: at block/blk-cgroup.c:867 blkcg_policy_register+0xb5/0xc0()
> Hardware name: Vostro 1520
> Modules linked in:
> Pid: 1, comm: swapper/0 Not tainted 3.5.0-rc3 #1
> Call Trace:
>  [<ffffffff8103a59a>] warn_slowpath_common+0x7a/0xb0
>  [<ffffffff81cafbed>] ? deadline_init+0x12/0x12
>  [<ffffffff8103a5e5>] warn_slowpath_null+0x15/0x20
>  [<ffffffff8131a6f5>] blkcg_policy_register+0xb5/0xc0
>  [<ffffffff81cafc2f>] cfq_init+0x42/0x9f
>  [<ffffffff810001ba>] do_one_initcall+0x3a/0x160
>  [<ffffffff81c8ed08>] kernel_init+0x137/0x1bb
>  [<ffffffff81c8e5c5>] ? do_early_param+0x87/0x87
>  [<ffffffff8169e3d4>] kernel_thread_helper+0x4/0x10
>  [<ffffffff81c8ebd1>] ? start_kernel+0x3b2/0x3b2
>  [<ffffffff8169e3d0>] ? gs_change+0xb/0xb
> ---[ end trace 82bc55f036371117 ]---

Can you please test the following branch?

  git://git.kernel.org/pub/scm/linux/kernel/git/axboe/linux-block.git for-linus

Thanks.

-- 
tejun

Re: 3.5.0-rc3 - Issue with CFQ and cgroup

[Paul Rolland]

Hello,

On Wed, 27 Jun 2012 11:22:02 -0700
Tejun Heo <tj@kernel.org> wrote:

> Hello,
> 
> > io scheduler noop registered
> Can you please test the following branch?
> 
>   git://git.kernel.org/pub/scm/linux/kernel/git/axboe/linux-block.git
> for-linus

Well code is the same.... so is the result :

[root@tux ~]# uname -a
Linux tux.DEF.witbe.net 3.5.0-rc4-g6b16351 #1 SMP PREEMPT Thu Jun 28
09:11:07 CEST 2012 x86_64 x86_64 x86_64 GNU/Linux

and

------------[ cut here ]------------
WARNING: at block/blk-cgroup.c:867 blkcg_policy_register+0xb5/0xc0()
Hardware name: Vostro 1520
Modules linked in:
Pid: 1, comm: swapper/0 Not tainted 3.5.0-rc4-g6b16351 #1
Call Trace:
 [<ffffffff8103a59a>] warn_slowpath_common+0x7a/0xb0
 [<ffffffff81cafbee>] ? deadline_init+0x12/0x12
 [<ffffffff8103a5e5>] warn_slowpath_null+0x15/0x20
 [<ffffffff8131aab5>] blkcg_policy_register+0xb5/0xc0
 [<ffffffff81cafc30>] cfq_init+0x42/0x9f
 [<ffffffff810001ba>] do_one_initcall+0x3a/0x160
 [<ffffffff81c8ed08>] kernel_init+0x137/0x1bb
 [<ffffffff81c8e5c5>] ? do_early_param+0x87/0x87
 [<ffffffff8169e954>] kernel_thread_helper+0x4/0x10
 [<ffffffff81c8ebd1>] ? start_kernel+0x3b2/0x3b2
 [<ffffffff8169e950>] ? gs_change+0xb/0xb
---[ end trace 82bc55f036371117 ]---

and of course cfq is missing in :
[root@tux ~]# cat /sys/block/sda/queue/scheduler 
[noop] deadline 

Looking at the code, it seems strange that cfq_init requires
blkcg_policy_register to be successfull, wether you have defined
CFQ_CGROUP_IOSCHED or not.

So, I applied the following patch, and I now have:
[root@tux ~]# cat /sys/block/sda/queue/scheduler 
noop deadline [cfq] 

Not sure this is the correct patch, but at least it works for me (tm) ;)

Signed-Off-by: Paul Rolland <rol@as2917.net> 

diff -urN block/cfq-iosched.orig block/cfq-iosched.c
--- block/cfq-iosched.orig      2012-06-28 09:39:06.000000000 +0200
+++ block/cfq-iosched.c 2012-06-28 09:39:31.000000000 +0200
@@ -4198,9 +4198,11 @@
                cfq_group_idle = 0;
 #endif
 
+#ifdef CONFIG_CFQ_GROUP_IOSCHED
        ret = blkcg_policy_register(&blkcg_policy_cfq);
        if (ret)
                return ret;
+#endif
 
        cfq_pool = KMEM_CACHE(cfq_queue, 0);
        if (!cfq_pool)
@@ -4215,7 +4217,9 @@
 err_free_pool:
        kmem_cache_destroy(cfq_pool);
 err_pol_unreg:
+#ifdef CONFIG_CFQ_GROUP_IOSCHED
        blkcg_policy_unregister(&blkcg_policy_cfq);
+#endif
        return ret;
 }


Paul

Re: 3.5.0-rc3 - Issue with CFQ and cgroup

[Tejun Heo]

Hello,

On Thu, Jun 28, 2012 at 09:51:03AM +0200, Paul Rolland wrote:
> >   git://git.kernel.org/pub/scm/linux/kernel/git/axboe/linux-block.git
> > for-linus
> 
> Well code is the same.... so is the result :

The code is not the same.  block/for-linus has several fixes which
haven't been pushed to mainline yet including the following commit.

Thanks.

>From ffea73fc723a12fdde4c9fb3fcce5d154d1104a1 Mon Sep 17 00:00:00 2001
From: Tejun Heo <tj@kernel.org>
Date: Mon, 4 Jun 2012 10:02:29 +0200
Subject: [PATCH] block: blkcg_policy_cfq shouldn't be used if
 !CONFIG_CFQ_GROUP_IOSCHED

cfq may be built w/ or w/o blkcg support depending on
CONFIG_CFQ_CGROUP_IOSCHED.  If blkcg support is disabled, most of
related code is ifdef'd out but some part is left dangling -
blkcg_policy_cfq is left zero-filled and blkcg_policy_[un]register()
calls are made on it.

Feeding zero filled policy to blkcg_policy_register() is incorrect and
triggers the following WARN_ON() if CONFIG_BLK_CGROUP &&
!CONFIG_CFQ_GROUP_IOSCHED.

 ------------[ cut here ]------------
 WARNING: at block/blk-cgroup.c:867
 Modules linked in:
 Modules linked in:
 CPU: 3 Not tainted 3.4.0-09547-gfb21aff #1
 Process swapper/0 (pid: 1, task: 000000003ff80000, ksp: 000000003ff7f8b8)
 Krnl PSW : 0704100180000000 00000000003d76ca (blkcg_policy_register+0xca/0xe0)
	    R:0 T:1 IO:1 EX:1 Key:0 M:1 W:0 P:0 AS:0 CC:1 PM:0 EA:3
 Krnl GPRS: 0000000000000000 00000000014b85ec 00000000014b85b0 0000000000000000
	    000000000096fb60 0000000000000000 00000000009a8e78 0000000000000048
	    000000000099c070 0000000000b6f000 0000000000000000 000000000099c0b8
	    00000000014b85b0 0000000000667580 000000003ff7fd98 000000003ff7fd70
 Krnl Code: 00000000003d76be: a7280001           lhi     %r2,1
	    00000000003d76c2: a7f4ffdf           brc     15,3d7680
	   #00000000003d76c6: a7f40001           brc     15,3d76c8
	   >00000000003d76ca: a7c8ffea           lhi     %r12,-22
	    00000000003d76ce: a7f4ffce           brc     15,3d766a
	    00000000003d76d2: a7f40001           brc     15,3d76d4
	    00000000003d76d6: a7c80000           lhi     %r12,0
	    00000000003d76da: a7f4ffc2           brc     15,3d765e
 Call Trace:
 ([<0000000000b6f000>] initcall_debug+0x0/0x4)
  [<0000000000989e8a>] cfq_init+0x62/0xd4
  [<00000000001000ba>] do_one_initcall+0x3a/0x170
  [<000000000096fb60>] kernel_init+0x214/0x2bc
  [<0000000000623202>] kernel_thread_starter+0x6/0xc
  [<00000000006231fc>] kernel_thread_starter+0x0/0xc
 no locks held by swapper/0/1.
 Last Breaking-Event-Address:
  [<00000000003d76c6>] blkcg_policy_register+0xc6/0xe0
 ---[ end trace b8ef4903fcbf9dd3 ]---

This patch fixes the problem by ensuring all blkcg support code is
inside CONFIG_CFQ_GROUP_IOSCHED.

* blkcg_policy_cfq declaration and blkg_to_cfqg() definition are moved
  inside the first CONFIG_CFQ_GROUP_IOSCHED block.  __maybe_unused is
  dropped from blkcg_policy_cfq decl.

* blkcg_deactivate_poilcy() invocation is moved inside ifdef.  This
  also makes the activation logic match cfq_init_queue().

* All blkcg_policy_[un]register() invocations are moved inside ifdef.

Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Heiko Carstens <heiko.carstens@de.ibm.com>
LKML-Reference: <20120601112954.GC3535@osiris.boeblingen.de.ibm.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
---
 block/cfq-iosched.c |   29 +++++++++++++++++------------
 1 files changed, 17 insertions(+), 12 deletions(-)

diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index ae5113d..fb52df9 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -17,8 +17,6 @@
 #include "blk.h"
 #include "blk-cgroup.h"
 
-static struct blkcg_policy blkcg_policy_cfq __maybe_unused;
-
 /*
  * tunables
  */
@@ -418,11 +416,6 @@ static inline struct cfq_group *pd_to_cfqg(struct blkg_policy_data *pd)
 	return pd ? container_of(pd, struct cfq_group, pd) : NULL;
 }
 
-static inline struct cfq_group *blkg_to_cfqg(struct blkcg_gq *blkg)
-{
-	return pd_to_cfqg(blkg_to_pd(blkg, &blkcg_policy_cfq));
-}
-
 static inline struct blkcg_gq *cfqg_to_blkg(struct cfq_group *cfqg)
 {
 	return pd_to_blkg(&cfqg->pd);
@@ -572,6 +565,13 @@ static inline void cfqg_stats_update_avg_queue_size(struct cfq_group *cfqg) { }
 
 #ifdef CONFIG_CFQ_GROUP_IOSCHED
 
+static struct blkcg_policy blkcg_policy_cfq;
+
+static inline struct cfq_group *blkg_to_cfqg(struct blkcg_gq *blkg)
+{
+	return pd_to_cfqg(blkg_to_pd(blkg, &blkcg_policy_cfq));
+}
+
 static inline void cfqg_get(struct cfq_group *cfqg)
 {
 	return blkg_get(cfqg_to_blkg(cfqg));
@@ -3951,10 +3951,11 @@ static void cfq_exit_queue(struct elevator_queue *e)
 
 	cfq_shutdown_timer_wq(cfqd);
 
-#ifndef CONFIG_CFQ_GROUP_IOSCHED
+#ifdef CONFIG_CFQ_GROUP_IOSCHED
+	blkcg_deactivate_policy(q, &blkcg_policy_cfq);
+#else
 	kfree(cfqd->root_group);
 #endif
-	blkcg_deactivate_policy(q, &blkcg_policy_cfq);
 	kfree(cfqd);
 }
 
@@ -4194,13 +4195,13 @@ static int __init cfq_init(void)
 #ifdef CONFIG_CFQ_GROUP_IOSCHED
 	if (!cfq_group_idle)
 		cfq_group_idle = 1;
-#else
-		cfq_group_idle = 0;
-#endif
 
 	ret = blkcg_policy_register(&blkcg_policy_cfq);
 	if (ret)
 		return ret;
+#else
+	cfq_group_idle = 0;
+#endif
 
 	ret = -ENOMEM;
 	cfq_pool = KMEM_CACHE(cfq_queue, 0);
@@ -4216,13 +4217,17 @@ static int __init cfq_init(void)
 err_free_pool:
 	kmem_cache_destroy(cfq_pool);
 err_pol_unreg:
+#ifdef CONFIG_CFQ_GROUP_IOSCHED
 	blkcg_policy_unregister(&blkcg_policy_cfq);
+#endif
 	return ret;
 }
 
 static void __exit cfq_exit(void)
 {
+#ifdef CONFIG_CFQ_GROUP_IOSCHED
 	blkcg_policy_unregister(&blkcg_policy_cfq);
+#endif
 	elv_unregister(&iosched_cfq);
 	kmem_cache_destroy(cfq_pool);
 }
-- 
1.7.7.3

Re: 3.5.0-rc3 - Issue with CFQ and cgroup

[Paul Rolland]

Hello,

On Thu, 28 Jun 2012 08:57:54 -0700
Tejun Heo <tj@kernel.org> wrote:

> Hello,
> 
> On Thu, Jun 28, 2012 at 09:51:03AM +0200, Paul Rolland wrote:
> > >   git://git.kernel.org/pub/scm/linux/kernel/git/axboe/linux-block.git
> > > for-linus
> > 
> > Well code is the same.... so is the result :
> 
> The code is not the same.  block/for-linus has several fixes which
> haven't been pushed to mainline yet including the following commit.

Then something is wrong, because the following commit doesn't seem to be
applied in the working copy I have :( 
For example, line 418, the code is :
static inline struct cfq_group *blkg_to_cfqg(struct blkcg_gq *blkg)
{
        return pd_to_cfqg(blkg_to_pd(blkg, &blkcg_policy_cfq));
}

which shouldn't be possible had the following commit been applied :(

What I did :
mkdir tejun
cd tejun
git init
git clone
git://git.kernel.org/pub/scm/linux/kernel/git/axboe/linux-block.git
for-linus

and then I chdir'ed into for-linus and rebuild a kernel locally...

Should I apply manually the patch below and retest ?

Paul
 
> Thanks.
> 
> >From ffea73fc723a12fdde4c9fb3fcce5d154d1104a1 Mon Sep 17 00:00:00 2001
> From: Tejun Heo <tj@kernel.org>
> Date: Mon, 4 Jun 2012 10:02:29 +0200
> Subject: [PATCH] block: blkcg_policy_cfq shouldn't be used if
>  !CONFIG_CFQ_GROUP_IOSCHED
> 
> cfq may be built w/ or w/o blkcg support depending on
> CONFIG_CFQ_CGROUP_IOSCHED.  If blkcg support is disabled, most of
> related code is ifdef'd out but some part is left dangling -
> blkcg_policy_cfq is left zero-filled and blkcg_policy_[un]register()
> calls are made on it.
> 
> Feeding zero filled policy to blkcg_policy_register() is incorrect and
> triggers the following WARN_ON() if CONFIG_BLK_CGROUP &&
> !CONFIG_CFQ_GROUP_IOSCHED.
> 
>  ------------[ cut here ]------------
>  WARNING: at block/blk-cgroup.c:867
>  Modules linked in:
>  Modules linked in:
>  CPU: 3 Not tainted 3.4.0-09547-gfb21aff #1
>  Process swapper/0 (pid: 1, task: 000000003ff80000, ksp: 000000003ff7f8b8)
>  Krnl PSW : 0704100180000000 00000000003d76ca
> (blkcg_policy_register+0xca/0xe0) R:0 T:1 IO:1 EX:1 Key:0 M:1 W:0 P:0
> AS:0 CC:1 PM:0 EA:3 Krnl GPRS: 0000000000000000 00000000014b85ec
> 00000000014b85b0 0000000000000000 000000000096fb60 0000000000000000
> 00000000009a8e78 0000000000000048 000000000099c070 0000000000b6f000
> 0000000000000000 000000000099c0b8 00000000014b85b0 0000000000667580
> 000000003ff7fd98 000000003ff7fd70 Krnl Code: 00000000003d76be:
> a7280001           lhi     %r2,1 00000000003d76c2: a7f4ffdf
> brc     15,3d7680 #00000000003d76c6: a7f40001           brc     15,3d76c8
> 	   >00000000003d76ca: a7c8ffea           lhi     %r12,-22
> 	    00000000003d76ce: a7f4ffce           brc     15,3d766a
> 	    00000000003d76d2: a7f40001           brc     15,3d76d4
> 	    00000000003d76d6: a7c80000           lhi     %r12,0
> 	    00000000003d76da: a7f4ffc2           brc     15,3d765e
>  Call Trace:
>  ([<0000000000b6f000>] initcall_debug+0x0/0x4)
>   [<0000000000989e8a>] cfq_init+0x62/0xd4
>   [<00000000001000ba>] do_one_initcall+0x3a/0x170
>   [<000000000096fb60>] kernel_init+0x214/0x2bc
>   [<0000000000623202>] kernel_thread_starter+0x6/0xc
>   [<00000000006231fc>] kernel_thread_starter+0x0/0xc
>  no locks held by swapper/0/1.
>  Last Breaking-Event-Address:
>   [<00000000003d76c6>] blkcg_policy_register+0xc6/0xe0
>  ---[ end trace b8ef4903fcbf9dd3 ]---
> 
> This patch fixes the problem by ensuring all blkcg support code is
> inside CONFIG_CFQ_GROUP_IOSCHED.
> 
> * blkcg_policy_cfq declaration and blkg_to_cfqg() definition are moved
>   inside the first CONFIG_CFQ_GROUP_IOSCHED block.  __maybe_unused is
>   dropped from blkcg_policy_cfq decl.
> 
> * blkcg_deactivate_poilcy() invocation is moved inside ifdef.  This
>   also makes the activation logic match cfq_init_queue().
> 
> * All blkcg_policy_[un]register() invocations are moved inside ifdef.
> 
> Signed-off-by: Tejun Heo <tj@kernel.org>
> Reported-by: Heiko Carstens <heiko.carstens@de.ibm.com>
> LKML-Reference: <20120601112954.GC3535@osiris.boeblingen.de.ibm.com>
> Signed-off-by: Jens Axboe <axboe@kernel.dk>
> ---
>  block/cfq-iosched.c |   29 +++++++++++++++++------------
>  1 files changed, 17 insertions(+), 12 deletions(-)
> 
> diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
> index ae5113d..fb52df9 100644
> --- a/block/cfq-iosched.c
> +++ b/block/cfq-iosched.c
> @@ -17,8 +17,6 @@
>  #include "blk.h"
>  #include "blk-cgroup.h"
>  
> -static struct blkcg_policy blkcg_policy_cfq __maybe_unused;
> -
>  /*
>   * tunables
>   */
> @@ -418,11 +416,6 @@ static inline struct cfq_group *pd_to_cfqg(struct
> blkg_policy_data *pd) return pd ? container_of(pd, struct cfq_group,
> pd) : NULL; }
>  
> -static inline struct cfq_group *blkg_to_cfqg(struct blkcg_gq *blkg)
> -{
> -	return pd_to_cfqg(blkg_to_pd(blkg, &blkcg_policy_cfq));
> -}
> -
>  static inline struct blkcg_gq *cfqg_to_blkg(struct cfq_group *cfqg)
>  {
>  	return pd_to_blkg(&cfqg->pd);
> @@ -572,6 +565,13 @@ static inline void
> cfqg_stats_update_avg_queue_size(struct cfq_group *cfqg) { } 
>  #ifdef CONFIG_CFQ_GROUP_IOSCHED
>  
> +static struct blkcg_policy blkcg_policy_cfq;
> +
> +static inline struct cfq_group *blkg_to_cfqg(struct blkcg_gq *blkg)
> +{
> +	return pd_to_cfqg(blkg_to_pd(blkg, &blkcg_policy_cfq));
> +}
> +
>  static inline void cfqg_get(struct cfq_group *cfqg)
>  {
>  	return blkg_get(cfqg_to_blkg(cfqg));
> @@ -3951,10 +3951,11 @@ static void cfq_exit_queue(struct elevator_queue
> *e) 
>  	cfq_shutdown_timer_wq(cfqd);
>  
> -#ifndef CONFIG_CFQ_GROUP_IOSCHED
> +#ifdef CONFIG_CFQ_GROUP_IOSCHED
> +	blkcg_deactivate_policy(q, &blkcg_policy_cfq);
> +#else
>  	kfree(cfqd->root_group);
>  #endif
> -	blkcg_deactivate_policy(q, &blkcg_policy_cfq);
>  	kfree(cfqd);
>  }
>  
> @@ -4194,13 +4195,13 @@ static int __init cfq_init(void)
>  #ifdef CONFIG_CFQ_GROUP_IOSCHED
>  	if (!cfq_group_idle)
>  		cfq_group_idle = 1;
> -#else
> -		cfq_group_idle = 0;
> -#endif
>  
>  	ret = blkcg_policy_register(&blkcg_policy_cfq);
>  	if (ret)
>  		return ret;
> +#else
> +	cfq_group_idle = 0;
> +#endif
>  
>  	ret = -ENOMEM;
>  	cfq_pool = KMEM_CACHE(cfq_queue, 0);
> @@ -4216,13 +4217,17 @@ static int __init cfq_init(void)
>  err_free_pool:
>  	kmem_cache_destroy(cfq_pool);
>  err_pol_unreg:
> +#ifdef CONFIG_CFQ_GROUP_IOSCHED
>  	blkcg_policy_unregister(&blkcg_policy_cfq);
> +#endif
>  	return ret;
>  }
>  
>  static void __exit cfq_exit(void)
>  {
> +#ifdef CONFIG_CFQ_GROUP_IOSCHED
>  	blkcg_policy_unregister(&blkcg_policy_cfq);
> +#endif
>  	elv_unregister(&iosched_cfq);
>  	kmem_cache_destroy(cfq_pool);
>  }


-- 
Paul Rolland                                E-Mail : rol(at)witbe.net
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or 15 years from now, she will come to me and say 'Daddy, where were you
when they took freedom of the press away from the Internet?'"
--Mike Godwin, Electronic Frontier Foundation 

Re: 3.5.0-rc3 - Issue with CFQ and cgroup

[Tejun Heo]

On Thu, Jun 28, 2012 at 06:04:43PM +0200, Paul Rolland wrote:
> What I did :
> mkdir tejun
> cd tejun
> git init
> git clone
> git://git.kernel.org/pub/scm/linux/kernel/git/axboe/linux-block.git
> for-linus

You cloned block tree into for-linus directory and then implicitly
used the master branch of the block tree, which is mainline.  What
should have been done are...

* git clone git://git.kernel....block.git block
* cd block
* git checkout for-linus

Thanks.

-- 
tejun

Re: 3.5.0-rc3 - Issue with CFQ and cgroup

[Paul Rolland]

Hello,

On Thu, 28 Jun 2012 09:08:55 -0700
Tejun Heo <tj@kernel.org> wrote:

> You cloned block tree into for-linus directory and then implicitly
> used the master branch of the block tree, which is mainline.  What
> should have been done are...
> 
> * git clone git://git.kernel....block.git block
> * cd block
> * git checkout for-linus

OK, just boot that version and it's fixing the issue (BTW, your patch is
nicer than mine ;)

Thanks,
Paul