From 575849ecf5d103ca9bbf0a6b9e89eba335d4e750 Mon Sep 17 00:00:00 2001 From: Filipe Manana Date: Wed, 11 Feb 2015 11:12:39 +0000 Subject: Btrfs: fix scheduler warning when syncing log We try to lock a mutex while the current task state is not TASK_RUNNING, which results in the following warning when CONFIG_DEBUG_LOCK_ALLOC=y: [30736.772501] ------------[ cut here ]------------ [30736.774545] WARNING: CPU: 9 PID: 19972 at kernel/sched/core.c:7300 __might_sleep+0x8b/0xa8() [30736.783453] do not call blocking ops when !TASK_RUNNING; state=2 set at [] prepare_to_wait+0x43/0x89 [30736.786261] Modules linked in: dm_flakey dm_mod crc32c_generic btrfs xor raid6_pq nfsd auth_rpcgss oid_registry nfs_acl nfs lockd grace fscache sunrpc loop parport_pc psmouse parport pcspkr microcode serio_raw evdev processor thermal_sys i2c_piix4 i2c_core button ext4 crc16 jbd2 mbcache sg sr_mod cdrom sd_mod ata_generic virtio_scsi floppy ata_piix libata virtio_pci virtio_ring e1000 virtio scsi_mod [30736.794323] CPU: 9 PID: 19972 Comm: fsstress Not tainted 3.19.0-rc7-btrfs-next-5+ #1 [30736.795821] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.7.5-0-ge51488c-20140602_164612-nilsson.home.kraxel.org 04/01/2014 [30736.798788] 0000000000000009 ffff88042743fbd8 ffffffff814248ed ffff88043d32f2d8 [30736.800504] ffff88042743fc28 ffff88042743fc18 ffffffff81045338 0000000000000001 [30736.802131] ffffffff81064514 ffffffff817c52d1 000000000000026d 0000000000000000 [30736.803676] Call Trace: [30736.804256] [] dump_stack+0x4c/0x65 [30736.805245] [] warn_slowpath_common+0xa1/0xbb [30736.806360] [] ? __might_sleep+0x8b/0xa8 [30736.807391] [] warn_slowpath_fmt+0x46/0x48 [30736.808511] [] ? prepare_to_wait+0x43/0x89 [30736.809620] [] ? prepare_to_wait+0x43/0x89 [30736.810691] [] __might_sleep+0x8b/0xa8 [30736.811703] [] mutex_lock_nested+0x2f/0x3a0 [30736.812889] [] ? trace_hardirqs_on_caller+0x18f/0x1ab [30736.814138] [] ? trace_hardirqs_on+0xd/0xf [30736.819878] [] wait_for_writer.isra.12+0x91/0xaa [btrfs] [30736.821260] [] ? signal_pending_state+0x31/0x31 [30736.822410] [] btrfs_sync_log+0x160/0x947 [btrfs] [30736.823574] [] ? trace_hardirqs_on_caller+0x18f/0x1ab [30736.824847] [] ? trace_hardirqs_on+0xd/0xf [30736.825972] [] btrfs_sync_file+0x2b0/0x319 [btrfs] [30736.827684] [] vfs_fsync_range+0x21/0x23 [30736.828932] [] vfs_fsync+0x1c/0x1e [30736.829917] [] do_fsync+0x34/0x4e [30736.830862] [] SyS_fsync+0x10/0x14 [30736.831819] [] system_call_fastpath+0x12/0x17 [30736.832982] ---[ end trace c0b57df60d32ae5c ]--- Fix this my acquiring the mutex after calling finish_wait(), which sets the task's state to TASK_RUNNING. Signed-off-by: Filipe Manana Reviewed-by: Liu Bo Signed-off-by: Chris Mason --- fs/btrfs/tree-log.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'fs/btrfs') diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c index 79f05bc9d6ec..7870bdba26b7 100644 --- a/fs/btrfs/tree-log.c +++ b/fs/btrfs/tree-log.c @@ -2448,8 +2448,8 @@ static void wait_for_writer(struct btrfs_trans_handle *trans, mutex_unlock(&root->log_mutex); if (atomic_read(&root->log_writers)) schedule(); - mutex_lock(&root->log_mutex); finish_wait(&root->log_writer_wait, &wait); + mutex_lock(&root->log_mutex); } } -- cgit v1.2.3