Patchwork [3.8.y.z,extended,stable] Patch "blkcg: fix "scheduling while atomic" in blk_queue_bypass_start" has been added to staging queue

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Submitter Kamal Mostafa
Date May 22, 2013, 9:55 p.m.
Message ID <>
Download mbox | patch
Permalink /patch/245726/
State New
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Kamal Mostafa - May 22, 2013, 9:55 p.m.
This is a note to let you know that I have just added a patch titled

    blkcg: fix "scheduling while atomic" in blk_queue_bypass_start

to the linux-3.8.y-queue branch of the 3.8.y.z extended stable tree 
which can be found at:;a=shortlog;h=refs/heads/linux-3.8.y-queue

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.8.y.z tree, see



From 63d0dd7ca4f6d49497b5baa3e55fe5b5acdec32d Mon Sep 17 00:00:00 2001
From: Jun'ichi Nomura <>
Date: Thu, 9 May 2013 09:55:08 +0900
Subject: blkcg: fix "scheduling while atomic" in blk_queue_bypass_start

commit e5072664f8237cf53b0bd68a51aa1a7bc69061c5 upstream.

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: [<ffffffffa019fb05>] 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:
   [<ffffffff810723ae>] __schedule_bug+0x6a/0x78
   [<ffffffff81428ba2>] __schedule+0xb4/0x5e0
   [<ffffffff814291e6>] schedule+0x64/0x66
   [<ffffffff8142773a>] schedule_timeout+0x39/0xf8
   [<ffffffff8108ad5f>] ? put_lock_stats+0xe/0x29
   [<ffffffff8108ae30>] ? lock_release_holdtime+0xb6/0xbb
   [<ffffffff814289e3>] wait_for_common+0x9d/0xee
   [<ffffffff8107526c>] ? try_to_wake_up+0x206/0x206
   [<ffffffff810c0eb8>] ? kfree_call_rcu+0x1c/0x1c
   [<ffffffff81428aec>] wait_for_completion+0x1d/0x1f
   [<ffffffff810611f9>] wait_rcu_gp+0x5d/0x7a
   [<ffffffff81061216>] ? wait_rcu_gp+0x7a/0x7a
   [<ffffffff8106fb18>] ? complete+0x21/0x53
   [<ffffffff810c0556>] synchronize_rcu+0x1e/0x20
   [<ffffffff811dd903>] blk_queue_bypass_start+0x5d/0x62
   [<ffffffff811ee109>] blkcg_activate_policy+0x73/0x270
   [<ffffffff81130521>] ? kmem_cache_alloc_node_trace+0xc7/0x108
   [<ffffffff811f04b3>] cfq_init_queue+0x80/0x28e
   [<ffffffffa01a1600>] ? dm_blk_ioctl+0xa7/0xa7 [dm_mod]
   [<ffffffff811d8c41>] elevator_init+0xe1/0x115
   [<ffffffff811e229f>] ? blk_queue_make_request+0x54/0x59
   [<ffffffff811dd743>] blk_init_allocated_queue+0x8c/0x9e
   [<ffffffffa019ffcd>] dm_setup_md_queue+0x36/0xaa [dm_mod]
   [<ffffffffa01a60e6>] table_load+0x1bd/0x2c8 [dm_mod]
   [<ffffffffa01a7026>] ctl_ioctl+0x1d6/0x236 [dm_mod]
   [<ffffffffa01a5f29>] ? table_clear+0xaa/0xaa [dm_mod]
   [<ffffffffa01a7099>] dm_ctl_ioctl+0x13/0x17 [dm_mod]
   [<ffffffff811479fc>] do_vfs_ioctl+0x3fb/0x441
   [<ffffffff811b643c>] ? file_has_perm+0x8a/0x99
   [<ffffffff81147aa0>] sys_ioctl+0x5e/0x82
   [<ffffffff812010be>] ? trace_hardirqs_on_thunk+0x3a/0x3f
   [<ffffffff814310d9>] system_call_fastpath+0x16/0x1b

Signed-off-by: Jun'ichi Nomura <>
Acked-by: Vivek Goyal <>
Acked-by: Tejun Heo <>
Cc: Alasdair G Kergon <>
Signed-off-by: Jens Axboe <>
[ Jun'ichi: backport to 3.8 ]
Signed-off-by: Kamal Mostafa <>
 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 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);

+	preloaded = !radix_tree_preload(GFP_KERNEL);
 	/* make sure the root blkg exists and count the existing blkgs */