| Message ID | 1391844788-14517-1-git-send-email-bo.li.liu@oracle.com (mailing list archive) |
|---|---|
| State | Accepted |
| Headers | show |
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c index de6a48f..735738b 100644 --- a/fs/btrfs/disk-io.c +++ b/fs/btrfs/disk-io.c @@ -3853,7 +3853,6 @@ static int btrfs_destroy_delayed_refs(struct btrfs_transaction *trans, rb_erase(&ref->rb_node, &head->ref_root); atomic_dec(&delayed_refs->num_entries); btrfs_put_delayed_ref(ref); - cond_resched_lock(&head->lock); } if (head->must_insert_reserved) pin_bytes = true;
Given now we have 2 spinlock for management of delayed refs, CONFIG_DEBUG_SPINLOCK=y helped me find this, [ 4723.413809] BUG: spinlock wrong CPU on CPU#1, btrfs-transacti/2258 [ 4723.414882] lock: 0xffff880048377670, .magic: dead4ead, .owner: btrfs-transacti/2258, .owner_cpu: 2 [ 4723.417146] CPU: 1 PID: 2258 Comm: btrfs-transacti Tainted: G W O 3.12.0+ #4 [ 4723.421321] Call Trace: [ 4723.421872] [<ffffffff81680fe7>] dump_stack+0x54/0x74 [ 4723.422753] [<ffffffff81681093>] spin_dump+0x8c/0x91 [ 4723.424979] [<ffffffff816810b9>] spin_bug+0x21/0x26 [ 4723.425846] [<ffffffff81323956>] do_raw_spin_unlock+0x66/0x90 [ 4723.434424] [<ffffffff81689bf7>] _raw_spin_unlock+0x27/0x40 [ 4723.438747] [<ffffffffa015da9e>] btrfs_cleanup_one_transaction+0x35e/0x710 [btrfs] [ 4723.443321] [<ffffffffa015df54>] btrfs_cleanup_transaction+0x104/0x570 [btrfs] [ 4723.444692] [<ffffffff810c1b5d>] ? trace_hardirqs_on_caller+0xfd/0x1c0 [ 4723.450336] [<ffffffff810c1c2d>] ? trace_hardirqs_on+0xd/0x10 [ 4723.451332] [<ffffffffa015e5ee>] transaction_kthread+0x22e/0x270 [btrfs] [ 4723.452543] [<ffffffffa015e3c0>] ? btrfs_cleanup_transaction+0x570/0x570 [btrfs] [ 4723.457833] [<ffffffff81079efa>] kthread+0xea/0xf0 [ 4723.458990] [<ffffffff81079e10>] ? kthread_create_on_node+0x140/0x140 [ 4723.460133] [<ffffffff81692aac>] ret_from_fork+0x7c/0xb0 [ 4723.460865] [<ffffffff81079e10>] ? kthread_create_on_node+0x140/0x140 [ 4723.496521] ------------[ cut here ]------------ ---------------------------------------------------------------------- The reason is that we get to call cond_resched_lock(&head_ref->lock) while still holding @delayed_refs->lock. So it's different with __btrfs_run_delayed_refs(), where we do drop-acquire dance before and after actually processing delayed refs. Here we don't drop the lock, others are not able to add new delayed refs to head_ref, so cond_resched_lock(&head_ref->lock) is not necessary here. Signed-off-by: Liu Bo <bo.li.liu@oracle.com> --- fs/btrfs/disk-io.c | 1 - 1 file changed, 1 deletion(-)