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Date: Mon, 4 Jun 2012 13:31:12 +0900
From: Tejun Heo <tj@...nel.org>
To: Jens Axboe <jaxboe@...ionio.com>,
Heiko Carstens <heiko.carstens@...ibm.com>
Cc: linux-kernel@...r.kernel.org
Subject: [PATCH 2/2] 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@...nel.org>
Reported-by: Heiko Carstens <heiko.carstens@...ibm.com>
LKML-Reference: <20120601112954.GC3535@...ris.boeblingen.de.ibm.com>
---
block/cfq-iosched.c | 29 +++++++++++++++++------------
1 file changed, 17 insertions(+), 12 deletions(-)
--- 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_cf
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
#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 elevat
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);
}
--
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