Re: [PATCH] blkcg: fix "scheduling while atomic" in blk_queue_bypass_start
On Tue, Oct 30, 2012 at 11:25:47AM +0900, Jun'ichi Nomura wrote: [..] > 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: (>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 > Cc: Vivek Goyal > Cc: Tejun Heo > Cc: Jens Axboe > Cc: Alasdair G Kergon > --- Thanks Junichi. This patch looks good to me. Acked-by: Vivek Goyal Vivek > 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 d0b7703..954f4be 100644 > --- a/block/blk-cgroup.c > +++ b/block/blk-cgroup.c > @@ -791,10 +791,10 @@ 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/
Re: [PATCH] blkcg: fix scheduling while atomic in blk_queue_bypass_start
On Tue, Oct 30, 2012 at 11:25:47AM +0900, Jun'ichi Nomura wrote: [..] 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: [a019fb05] dm_lock_md_type+0x17/0x19 [dm_mod] Modules linked in: ... Pid: 2460, comm: multipath Tainted: GW3.7.0-rc2 #1 Call Trace: [810723ae] __schedule_bug+0x6a/0x78 [81428ba2] __schedule+0xb4/0x5e0 [814291e6] schedule+0x64/0x66 [8142773a] schedule_timeout+0x39/0xf8 [8108ad5f] ? put_lock_stats+0xe/0x29 [8108ae30] ? lock_release_holdtime+0xb6/0xbb [814289e3] wait_for_common+0x9d/0xee [8107526c] ? try_to_wake_up+0x206/0x206 [810c0eb8] ? kfree_call_rcu+0x1c/0x1c [81428aec] wait_for_completion+0x1d/0x1f [810611f9] wait_rcu_gp+0x5d/0x7a [81061216] ? wait_rcu_gp+0x7a/0x7a [8106fb18] ? complete+0x21/0x53 [810c0556] synchronize_rcu+0x1e/0x20 [811dd903] blk_queue_bypass_start+0x5d/0x62 [811ee109] blkcg_activate_policy+0x73/0x270 [81130521] ? kmem_cache_alloc_node_trace+0xc7/0x108 [811f04b3] cfq_init_queue+0x80/0x28e [a01a1600] ? dm_blk_ioctl+0xa7/0xa7 [dm_mod] [811d8c41] elevator_init+0xe1/0x115 [811e229f] ? blk_queue_make_request+0x54/0x59 [811dd743] blk_init_allocated_queue+0x8c/0x9e [a019ffcd] dm_setup_md_queue+0x36/0xaa [dm_mod] [a01a60e6] table_load+0x1bd/0x2c8 [dm_mod] [a01a7026] ctl_ioctl+0x1d6/0x236 [dm_mod] [a01a5f29] ? table_clear+0xaa/0xaa [dm_mod] [a01a7099] dm_ctl_ioctl+0x13/0x17 [dm_mod] [811479fc] do_vfs_ioctl+0x3fb/0x441 [811b643c] ? file_has_perm+0x8a/0x99 [81147aa0] sys_ioctl+0x5e/0x82 [812010be] ? trace_hardirqs_on_thunk+0x3a/0x3f [814310d9] system_call_fastpath+0x16/0x1b Signed-off-by: Jun'ichi Nomura j-nom...@ce.jp.nec.com Cc: Vivek Goyal vgo...@redhat.com Cc: Tejun Heo t...@kernel.org Cc: Jens Axboe ax...@kernel.dk Cc: Alasdair G Kergon a...@redhat.com --- Thanks Junichi. This patch looks good to me. Acked-by: Vivek Goyal vgo...@redhat.com Vivek 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 d0b7703..954f4be 100644 --- a/block/blk-cgroup.c +++ b/block/blk-cgroup.c @@ -791,10 +791,10 @@ 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/
[PATCH] blkcg: fix "scheduling while atomic" in blk_queue_bypass_start
On 10/30/12 02:13, Vivek Goyal wrote: > On Mon, Oct 29, 2012 at 05:45:15PM +0100, Peter Zijlstra wrote: >> int radix_tree_preload(gfp_t gfp_mask) >> { >> struct radix_tree_preload *rtp; >> struct radix_tree_node *node; >> int ret = -ENOMEM; >> >> preempt_disable(); >> >> >> Seems obvious why it explodes.. > > Oh right. Thanks Peter. So just calling blk_queue_bypass_start() before > radix_tree_preload() should fix it. Junichi, can you please give it > a try. Thank you! It just works. This is a revised patch. With 749fefe677 ("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: (>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 Cc: 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 d0b7703..954f4be 100644 --- a/block/blk-cgroup.c +++ b/block/blk-cgroup.c @@ -791,10 +791,10 @@ 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/
[PATCH] blkcg: fix scheduling while atomic in blk_queue_bypass_start
On 10/30/12 02:13, Vivek Goyal wrote: On Mon, Oct 29, 2012 at 05:45:15PM +0100, Peter Zijlstra wrote: int radix_tree_preload(gfp_t gfp_mask) { struct radix_tree_preload *rtp; struct radix_tree_node *node; int ret = -ENOMEM; preempt_disable(); Seems obvious why it explodes.. Oh right. Thanks Peter. So just calling blk_queue_bypass_start() before radix_tree_preload() should fix it. Junichi, can you please give it a try. Thank you! It just works. This is a revised patch. With 749fefe677 (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: [a019fb05] dm_lock_md_type+0x17/0x19 [dm_mod] Modules linked in: ... Pid: 2460, comm: multipath Tainted: GW3.7.0-rc2 #1 Call Trace: [810723ae] __schedule_bug+0x6a/0x78 [81428ba2] __schedule+0xb4/0x5e0 [814291e6] schedule+0x64/0x66 [8142773a] schedule_timeout+0x39/0xf8 [8108ad5f] ? put_lock_stats+0xe/0x29 [8108ae30] ? lock_release_holdtime+0xb6/0xbb [814289e3] wait_for_common+0x9d/0xee [8107526c] ? try_to_wake_up+0x206/0x206 [810c0eb8] ? kfree_call_rcu+0x1c/0x1c [81428aec] wait_for_completion+0x1d/0x1f [810611f9] wait_rcu_gp+0x5d/0x7a [81061216] ? wait_rcu_gp+0x7a/0x7a [8106fb18] ? complete+0x21/0x53 [810c0556] synchronize_rcu+0x1e/0x20 [811dd903] blk_queue_bypass_start+0x5d/0x62 [811ee109] blkcg_activate_policy+0x73/0x270 [81130521] ? kmem_cache_alloc_node_trace+0xc7/0x108 [811f04b3] cfq_init_queue+0x80/0x28e [a01a1600] ? dm_blk_ioctl+0xa7/0xa7 [dm_mod] [811d8c41] elevator_init+0xe1/0x115 [811e229f] ? blk_queue_make_request+0x54/0x59 [811dd743] blk_init_allocated_queue+0x8c/0x9e [a019ffcd] dm_setup_md_queue+0x36/0xaa [dm_mod] [a01a60e6] table_load+0x1bd/0x2c8 [dm_mod] [a01a7026] ctl_ioctl+0x1d6/0x236 [dm_mod] [a01a5f29] ? table_clear+0xaa/0xaa [dm_mod] [a01a7099] dm_ctl_ioctl+0x13/0x17 [dm_mod] [811479fc] do_vfs_ioctl+0x3fb/0x441 [811b643c] ? file_has_perm+0x8a/0x99 [81147aa0] sys_ioctl+0x5e/0x82 [812010be] ? trace_hardirqs_on_thunk+0x3a/0x3f [814310d9] system_call_fastpath+0x16/0x1b Signed-off-by: Jun'ichi Nomura j-nom...@ce.jp.nec.com Cc: Vivek Goyal vgo...@redhat.com Cc: Tejun Heo t...@kernel.org Cc: Jens Axboe ax...@kernel.dk Cc: Alasdair G Kergon a...@redhat.com --- 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 d0b7703..954f4be 100644 --- a/block/blk-cgroup.c +++ b/block/blk-cgroup.c @@ -791,10 +791,10 @@ 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/