The function raid10_unplug tests the "from_schedule" variable. If the variable is true, it offloads queued bios to a thread. If the variable is false, it submits queued bios directly. The function io_schedule calls blk_flush_plug, that calls blk_flush_plug_list with "from_schedule" set to false. Consequently, raid10_unplug tries to submit the bios directly when being called from io_schedule, and that results in this warning. Fix the bug by calling blk_schedule_flush_plug instead of blk_flush_plug from io_schedule. WARNING: CPU: 0 PID: 2876 at kernel/sched/core.c:7326 __might_sleep+0xae/0xc0() md: using maximum available idle IO bandwidth (but not more than 200000 KB/sec) for resync. do not call blocking ops when !TASK_RUNNING; state=2 set at [<ffffffff81232b10>] do_blockdev_direct_IO+0x11a0/0x2e50 Modules linked in: loop dm_raid raid456 async_raid6_recov async_memcpy async_pq async_xor async_tx raid1 raid10 xor raid6_pq nfsv4 nfs nfsd auth_rpcgss oid_registry nfs_acl lockd grace sunrpc autofs4 fuse dm_crypt md_mod uhci_hcd ehci_hcd usbcore i2c_piix4 serio_raw i2c_core virtio_net usb_common floppy pvpanic evdev sym53c8xx dm_mirror dm_region_hash dm_log dm_mod md: using 128k window, over a total of 1024k. CPU: 0 PID: 2876 Comm: lvm Not tainted 3.19.0-rc7-00195-gd4cecd5 #7 Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011 ffffffff819e4eba ffff88003c493818 ffffffff8163975d 0000000000000007 ffff88003c493868 ffff88003c493858 ffffffff810587ba 00000000001d4280 ffffffffa013b2b4 00000000000002e9 0000000000000000 ffff88003a8be010 Call Trace: [<ffffffff8163975d>] dump_stack+0x4f/0x7b [<ffffffff810587ba>] warn_slowpath_common+0x8a/0xc0 [<ffffffff81058836>] warn_slowpath_fmt+0x46/0x50 [<ffffffff810af221>] ? __lock_acquire+0x411/0x1d10 [<ffffffff81232b10>] ? do_blockdev_direct_IO+0x11a0/0x2e50 [<ffffffff81232b10>] ? do_blockdev_direct_IO+0x11a0/0x2e50 [<ffffffff810842ae>] __might_sleep+0xae/0xc0 [<ffffffffa0131816>] md_super_wait+0x26/0x90 [md_mod] [<ffffffffa0138903>] bitmap_unplug+0x193/0x1a0 [md_mod] [<ffffffff8112ce33>] ? __delayacct_blkio_start+0x23/0x30 [<ffffffffa00ee940>] raid10_unplug+0xe0/0x160 [raid10] [<ffffffff8136d01a>] blk_flush_plug_list+0xaa/0x250 [<ffffffff810aeafd>] ? trace_hardirqs_on+0xd/0x10 [<ffffffff8163b602>] io_schedule+0x82/0x150 [<ffffffff81232b3a>] do_blockdev_direct_IO+0x11ca/0x2e50 [<ffffffff810914a5>] ? sched_clock_local+0x25/0x90 [<ffffffff8122ed00>] ? I_BDEV+0x10/0x10 [<ffffffff8123480c>] __blockdev_direct_IO+0x4c/0x50 [<ffffffff8122ed00>] ? I_BDEV+0x10/0x10 [<ffffffff8122f4ce>] blkdev_direct_IO+0x4e/0x50 [<ffffffff8122ed00>] ? I_BDEV+0x10/0x10 [<ffffffff8117a095>] generic_file_direct_write+0xb5/0x190 [<ffffffff8117a455>] __generic_file_write_iter+0x2e5/0x390 [<ffffffff8122f7ff>] blkdev_write_iter+0x2f/0xa0 [<ffffffff811ece11>] new_sync_write+0x81/0xb0 [<ffffffff811ed61a>] vfs_write+0xba/0x1f0 [<ffffffff811ee269>] SyS_write+0x49/0xb0 [<ffffffff81645063>] sysenter_dispatch+0x7/0x1f [<ffffffff813a24db>] ? trace_hardirqs_on_thunk+0x3a/0x3f ---[ end trace 28ea2673fb871796 ]--- Signed-off-by: Mikulas Patocka <mpatocka@xxxxxxxxxx> Reported-by: Zdenek Kabelac <zkabelac@xxxxxxxxxx> Cc: stable@xxxxxxxxxxxxxxx # 2.6.39+ --- kernel/sched/core.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) Index: linux-2.6/kernel/sched/core.c =================================================================== --- linux-2.6.orig/kernel/sched/core.c 2015-02-09 11:35:35.169156491 +0100 +++ linux-2.6/kernel/sched/core.c 2015-02-09 12:11:35.140557980 +0100 @@ -4397,7 +4397,7 @@ void __sched io_schedule(void) delayacct_blkio_start(); atomic_inc(&rq->nr_iowait); - blk_flush_plug(current); + blk_schedule_flush_plug(current); current->in_iowait = 1; schedule(); current->in_iowait = 0; @@ -4413,7 +4413,7 @@ long __sched io_schedule_timeout(long ti delayacct_blkio_start(); atomic_inc(&rq->nr_iowait); - blk_flush_plug(current); + blk_schedule_flush_plug(current); current->in_iowait = 1; ret = schedule_timeout(timeout); current->in_iowait = 0; -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
