From e5072664f8237cf53b0bd68a51aa1a7bc69061c5 Mon Sep 17 00:00:00 2001 From: Jun'ichi Nomura Date: Tue, 9 Apr 2013 15:01:21 +0200 Subject: blkcg: fix "scheduling while atomic" in blk_queue_bypass_start 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/2460/0x00000002 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: G W 3.7.0-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: Alasdair G Kergon Cc: stable@kernel.org Signed-off-by: Jens Axboe --- block/blk-cgroup.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c index b2b9837f9dd3..e8918ffaf96d 100644 --- a/block/blk-cgroup.c +++ b/block/blk-cgroup.c @@ -972,10 +972,10 @@ int blkcg_activate_policy(struct request_queue *q, if (!new_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. As * @q is bypassing at this point, blkg_lookup_create() can't be -- cgit v1.2.3