[PATCH repost] blkcg: fix "scheduling while atomic" in blk_queue_bypass_start
Hello Jens,
please consider to pick up this patch.
Without this patch, the warning below splats every when a multipath
device is created.
I got acks from Vivek and Tejun when I posted this for v3.7
and this same patch is still applicable to v3.8.
Since 749fefe677 in v3.7 ("block: lift the initial queue bypass mode
on blk_register_queue() instead of blk_init_allocated_queue()"),
the following warning appears when multipath is used with CONFIG_PREEMPT=y.
This patch moves blk_queue_bypass_start() before radix_tree_preload()
to avoid the sleeping call while preemption is disabled.
BUG: scheduling while atomic: multipath/2460/0x0002
1 lock held by multipath/2460:
#0: (&md->type_lock){..}, at: []
dm_lock_md_type+0x17/0x19 [dm_mod]
Modules linked in: ...
Pid: 2460, comm: multipath Tainted: GW3.7.0-rc2 #1
Call Trace:
[] __schedule_bug+0x6a/0x78
[] __schedule+0xb4/0x5e0
[] schedule+0x64/0x66
[] schedule_timeout+0x39/0xf8
[] ? put_lock_stats+0xe/0x29
[] ? lock_release_holdtime+0xb6/0xbb
[] wait_for_common+0x9d/0xee
[] ? try_to_wake_up+0x206/0x206
[] ? kfree_call_rcu+0x1c/0x1c
[] wait_for_completion+0x1d/0x1f
[] wait_rcu_gp+0x5d/0x7a
[] ? wait_rcu_gp+0x7a/0x7a
[] ? complete+0x21/0x53
[] synchronize_rcu+0x1e/0x20
[] blk_queue_bypass_start+0x5d/0x62
[] blkcg_activate_policy+0x73/0x270
[] ? kmem_cache_alloc_node_trace+0xc7/0x108
[] cfq_init_queue+0x80/0x28e
[] ? dm_blk_ioctl+0xa7/0xa7 [dm_mod]
[] elevator_init+0xe1/0x115
[] ? blk_queue_make_request+0x54/0x59
[] blk_init_allocated_queue+0x8c/0x9e
[] dm_setup_md_queue+0x36/0xaa [dm_mod]
[] table_load+0x1bd/0x2c8 [dm_mod]
[] ctl_ioctl+0x1d6/0x236 [dm_mod]
[] ? table_clear+0xaa/0xaa [dm_mod]
[] dm_ctl_ioctl+0x13/0x17 [dm_mod]
[] do_vfs_ioctl+0x3fb/0x441
[] ? file_has_perm+0x8a/0x99
[] sys_ioctl+0x5e/0x82
[] ? trace_hardirqs_on_thunk+0x3a/0x3f
[] system_call_fastpath+0x16/0x1b
Signed-off-by: Jun'ichi Nomura
Acked-by: Vivek Goyal
Acked-by: Tejun Heo
Cc: Jens Axboe
Cc: Alasdair G Kergon
---
block/blk-cgroup.c |4 ++--
1 files changed, 2 insertions(+), 2 deletions(-)
diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
index b8858fb..53628e4 100644
--- a/block/blk-cgroup.c
+++ b/block/blk-cgroup.c
@@ -790,10 +790,10 @@ int blkcg_activate_policy(struct request_queue *q,
if (!blkg)
return -ENOMEM;
- preloaded = !radix_tree_preload(GFP_KERNEL);
-
blk_queue_bypass_start(q);
+ preloaded = !radix_tree_preload(GFP_KERNEL);
+
/* make sure the root blkg exists and count the existing blkgs */
spin_lock_irq(q->queue_lock);
--
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Re: [PATCH repost] blkcg: fix "scheduling while atomic" in blk_queue_bypass_start
On Tue, Jan 08, 2013 at 04:31:30PM +0900, Jun'ichi Nomura wrote:
> With 749fefe677 in v3.7 ("block: lift the initial queue bypass mode
> on blk_register_queue() instead of blk_init_allocated_queue()"),
> the following warning appears when multipath is used with CONFIG_PREEMPT=y.
>
> This patch moves blk_queue_bypass_start() before radix_tree_preload()
> to avoid the sleeping call while preemption is disabled.
>
> BUG: scheduling while atomic: multipath/2460/0x0002
> 1 lock held by multipath/2460:
>#0: (&md->type_lock){..}, at: []
> dm_lock_md_type+0x17/0x19 [dm_mod]
> Modules linked in: ...
> Pid: 2460, comm: multipath Tainted: GW3.7.0-rc2 #1
> Call Trace:
>[] __schedule_bug+0x6a/0x78
>[] __schedule+0xb4/0x5e0
>[] schedule+0x64/0x66
>[] schedule_timeout+0x39/0xf8
>[] ? put_lock_stats+0xe/0x29
>[] ? lock_release_holdtime+0xb6/0xbb
>[] wait_for_common+0x9d/0xee
>[] ? try_to_wake_up+0x206/0x206
>[] ? kfree_call_rcu+0x1c/0x1c
>[] wait_for_completion+0x1d/0x1f
>[] wait_rcu_gp+0x5d/0x7a
>[] ? wait_rcu_gp+0x7a/0x7a
>[] ? complete+0x21/0x53
>[] synchronize_rcu+0x1e/0x20
>[] blk_queue_bypass_start+0x5d/0x62
>[] blkcg_activate_policy+0x73/0x270
>[] ? kmem_cache_alloc_node_trace+0xc7/0x108
>[] cfq_init_queue+0x80/0x28e
>[] ? dm_blk_ioctl+0xa7/0xa7 [dm_mod]
>[] elevator_init+0xe1/0x115
>[] ? blk_queue_make_request+0x54/0x59
>[] blk_init_allocated_queue+0x8c/0x9e
>[] dm_setup_md_queue+0x36/0xaa [dm_mod]
>[] table_load+0x1bd/0x2c8 [dm_mod]
>[] ctl_ioctl+0x1d6/0x236 [dm_mod]
>[] ? table_clear+0xaa/0xaa [dm_mod]
>[] dm_ctl_ioctl+0x13/0x17 [dm_mod]
>[] do_vfs_ioctl+0x3fb/0x441
>[] ? file_has_perm+0x8a/0x99
>[] sys_ioctl+0x5e/0x82
>[] ? trace_hardirqs_on_thunk+0x3a/0x3f
>[] system_call_fastpath+0x16/0x1b
>
> Signed-off-by: Jun'ichi Nomura
> Acked-by: Vivek Goyal
> Cc: Tejun Heo
> Cc: Jens Axboe
> Cc: Alasdair G Kergon
Acked-by: Tejun Heo
Thanks.
--
tejun
--
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Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH repost] blkcg: fix "scheduling while atomic" in blk_queue_bypass_start
On Tue, Jan 08, 2013 at 04:31:30PM +0900, Jun'ichi Nomura wrote:
> With 749fefe677 in v3.7 ("block: lift the initial queue bypass mode
> on blk_register_queue() instead of blk_init_allocated_queue()"),
> the following warning appears when multipath is used with CONFIG_PREEMPT=y.
>
> This patch moves blk_queue_bypass_start() before radix_tree_preload()
> to avoid the sleeping call while preemption is disabled.
Ok, raix_tree_preload() disabled preemption and blk_queue_bypass_start()
calls synchronize_rcu() which in turn leads to schedule(), hence the
warning.
We also call __blkg_lookup_create() with preemption disabled and this
can do blkg allocation. But allocation currently is GFP_ATOMIC, so not
sleeping and scheduling here. So it should be fine.
So fix looks good to me.
Acked-by: Vivek Goyal
Vivek
>
> BUG: scheduling while atomic: multipath/2460/0x0002
> 1 lock held by multipath/2460:
>#0: (&md->type_lock){..}, at: []
> dm_lock_md_type+0x17/0x19 [dm_mod]
> Modules linked in: ...
> Pid: 2460, comm: multipath Tainted: GW3.7.0-rc2 #1
> Call Trace:
>[] __schedule_bug+0x6a/0x78
>[] __schedule+0xb4/0x5e0
>[] schedule+0x64/0x66
>[] schedule_timeout+0x39/0xf8
>[] ? put_lock_stats+0xe/0x29
>[] ? lock_release_holdtime+0xb6/0xbb
>[] wait_for_common+0x9d/0xee
>[] ? try_to_wake_up+0x206/0x206
>[] ? kfree_call_rcu+0x1c/0x1c
>[] wait_for_completion+0x1d/0x1f
>[] wait_rcu_gp+0x5d/0x7a
>[] ? wait_rcu_gp+0x7a/0x7a
>[] ? complete+0x21/0x53
>[] synchronize_rcu+0x1e/0x20
>[] blk_queue_bypass_start+0x5d/0x62
>[] blkcg_activate_policy+0x73/0x270
>[] ? kmem_cache_alloc_node_trace+0xc7/0x108
>[] cfq_init_queue+0x80/0x28e
>[] ? dm_blk_ioctl+0xa7/0xa7 [dm_mod]
>[] elevator_init+0xe1/0x115
>[] ? blk_queue_make_request+0x54/0x59
>[] blk_init_allocated_queue+0x8c/0x9e
>[] dm_setup_md_queue+0x36/0xaa [dm_mod]
>[] table_load+0x1bd/0x2c8 [dm_mod]
>[] ctl_ioctl+0x1d6/0x236 [dm_mod]
>[] ? table_clear+0xaa/0xaa [dm_mod]
>[] dm_ctl_ioctl+0x13/0x17 [dm_mod]
>[] do_vfs_ioctl+0x3fb/0x441
>[] ? file_has_perm+0x8a/0x99
>[] sys_ioctl+0x5e/0x82
>[] ? trace_hardirqs_on_thunk+0x3a/0x3f
>[] system_call_fastpath+0x16/0x1b
>
> Signed-off-by: Jun'ichi Nomura
> Acked-by: Vivek Goyal
> Cc: Tejun Heo
> Cc: Jens Axboe
> Cc: Alasdair G Kergon
> ---
> block/blk-cgroup.c |4 ++--
> 1 files changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
> index b8858fb..53628e4 100644
> --- a/block/blk-cgroup.c
> +++ b/block/blk-cgroup.c
> @@ -790,10 +790,10 @@ int blkcg_activate_policy(struct request_queue *q,
> if (!blkg)
> return -ENOMEM;
>
> - preloaded = !radix_tree_preload(GFP_KERNEL);
> -
> blk_queue_bypass_start(q);
>
> + preloaded = !radix_tree_preload(GFP_KERNEL);
> +
> /* make sure the root blkg exists and count the existing blkgs */
> spin_lock_irq(q->queue_lock);
>
--
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Please read the FAQ at http://www.tux.org/lkml/
[PATCH repost] blkcg: fix "scheduling while atomic" in blk_queue_bypass_start
With 749fefe677 in v3.7 ("block: lift the initial queue bypass mode
on blk_register_queue() instead of blk_init_allocated_queue()"),
the following warning appears when multipath is used with CONFIG_PREEMPT=y.
This patch moves blk_queue_bypass_start() before radix_tree_preload()
to avoid the sleeping call while preemption is disabled.
BUG: scheduling while atomic: multipath/2460/0x0002
1 lock held by multipath/2460:
#0: (&md->type_lock){..}, at: []
dm_lock_md_type+0x17/0x19 [dm_mod]
Modules linked in: ...
Pid: 2460, comm: multipath Tainted: GW3.7.0-rc2 #1
Call Trace:
[] __schedule_bug+0x6a/0x78
[] __schedule+0xb4/0x5e0
[] schedule+0x64/0x66
[] schedule_timeout+0x39/0xf8
[] ? put_lock_stats+0xe/0x29
[] ? lock_release_holdtime+0xb6/0xbb
[] wait_for_common+0x9d/0xee
[] ? try_to_wake_up+0x206/0x206
[] ? kfree_call_rcu+0x1c/0x1c
[] wait_for_completion+0x1d/0x1f
[] wait_rcu_gp+0x5d/0x7a
[] ? wait_rcu_gp+0x7a/0x7a
[] ? complete+0x21/0x53
[] synchronize_rcu+0x1e/0x20
[] blk_queue_bypass_start+0x5d/0x62
[] blkcg_activate_policy+0x73/0x270
[] ? kmem_cache_alloc_node_trace+0xc7/0x108
[] cfq_init_queue+0x80/0x28e
[] ? dm_blk_ioctl+0xa7/0xa7 [dm_mod]
[] elevator_init+0xe1/0x115
[] ? blk_queue_make_request+0x54/0x59
[] blk_init_allocated_queue+0x8c/0x9e
[] dm_setup_md_queue+0x36/0xaa [dm_mod]
[] table_load+0x1bd/0x2c8 [dm_mod]
[] ctl_ioctl+0x1d6/0x236 [dm_mod]
[] ? table_clear+0xaa/0xaa [dm_mod]
[] dm_ctl_ioctl+0x13/0x17 [dm_mod]
[] do_vfs_ioctl+0x3fb/0x441
[] ? file_has_perm+0x8a/0x99
[] sys_ioctl+0x5e/0x82
[] ? trace_hardirqs_on_thunk+0x3a/0x3f
[] system_call_fastpath+0x16/0x1b
Signed-off-by: Jun'ichi Nomura
Acked-by: Vivek Goyal
Cc: Tejun Heo
Cc: Jens Axboe
Cc: Alasdair G Kergon
---
block/blk-cgroup.c |4 ++--
1 files changed, 2 insertions(+), 2 deletions(-)
diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
index b8858fb..53628e4 100644
--- a/block/blk-cgroup.c
+++ b/block/blk-cgroup.c
@@ -790,10 +790,10 @@ int blkcg_activate_policy(struct request_queue *q,
if (!blkg)
return -ENOMEM;
- preloaded = !radix_tree_preload(GFP_KERNEL);
-
blk_queue_bypass_start(q);
+ preloaded = !radix_tree_preload(GFP_KERNEL);
+
/* make sure the root blkg exists and count the existing blkgs */
spin_lock_irq(q->queue_lock);
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
