From: Filipe Manana <fdman...@suse.com>
We are holding a btree path with spinning locks and then we attempt to
clone an extent buffer, which calls kmem_cache_alloc() and this function
can sleep, causing the following trace to be reported on a debug kernel:
[107118.218536] BUG: sleeping function called from invalid context at
mm/slab.c:2871
[107118.224110] in_atomic(): 1, irqs_disabled(): 0, pid: 19148, name:
kworker/u32:3
[107118.226120] INFO: lockdep is turned off.
[107118.226843] Preemption disabled at:[<ffffffffa05ffa22>]
btrfs_clear_lock_blocking_rw+0x96/0xea [btrfs]
[107118.229175] CPU: 3 PID: 19148 Comm: kworker/u32:3 Tainted: G W
4.3.0-rc5-btrfs-next-17+ #1
[107118.231326] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
rel-1.8.1-0-g4adadbd-20150316_085822-nilsson.home.kraxel.org 04/01/2014
[107118.233687] Workqueue: btrfs-qgroup-rescan btrfs_qgroup_rescan_helper
[btrfs]
[107118.236835] 0000000000000000 ffff880424bf3b78 ffffffff812566f4
0000000000000000
[107118.238369] ffff880424bf3ba0 ffffffff81070664 ffffffff817f1cd5
0000000000000b37
[107118.239769] 0000000000000000 ffff880424bf3bc8 ffffffff8107070a
0000000000008850
[107118.241244] Call Trace:
[107118.241729] [<ffffffff812566f4>] dump_stack+0x4e/0x79
[107118.242602] [<ffffffff81070664>] ___might_sleep+0x23a/0x241
[107118.243586] [<ffffffff8107070a>] __might_sleep+0x9f/0xa6
[107118.244532] [<ffffffff8115af70>] cache_alloc_debugcheck_before+0x25/0x36
[107118.245939] [<ffffffff8115d52b>] kmem_cache_alloc+0x50/0x215
[107118.246930] [<ffffffffa05e627e>] __alloc_extent_buffer+0x2a/0x11f [btrfs]
[107118.248121] [<ffffffffa05ecb1a>] btrfs_clone_extent_buffer+0x3d/0xdd
[btrfs]
[107118.249451] [<ffffffffa06239ea>] btrfs_qgroup_rescan_worker+0x16d/0x434
[btrfs]
[107118.250755] [<ffffffff81087481>] ? arch_local_irq_save+0x9/0xc
[107118.251754] [<ffffffffa05f7952>] normal_work_helper+0x14c/0x32a [btrfs]
[107118.252899] [<ffffffffa05f7952>] ? normal_work_helper+0x14c/0x32a [btrfs]
[107118.254195] [<ffffffffa05f7c82>] btrfs_qgroup_rescan_helper+0x12/0x14
[btrfs]
[107118.255436] [<ffffffff81063b23>] process_one_work+0x24a/0x4ac
[107118.263690] [<ffffffff81064285>] worker_thread+0x206/0x2c2
[107118.264888] [<ffffffff8106407f>] ? rescuer_thread+0x2cb/0x2cb
[107118.267413] [<ffffffff8106904d>] kthread+0xef/0xf7
[107118.268417] [<ffffffff81068f5e>] ? kthread_parkme+0x24/0x24
[107118.269505] [<ffffffff8147d10f>] ret_from_fork+0x3f/0x70
[107118.270491] [<ffffffff81068f5e>] ? kthread_parkme+0x24/0x24
So just use blocking locks for our path to solve this.
This fixes the patch titled:
"btrfs: qgroup: Don't copy extent buffer to do qgroup rescan"
Signed-off-by: Filipe Manana <fdman...@suse.com>
---
fs/btrfs/qgroup.c | 1 -
1 file changed, 1 deletion(-)
diff --git a/fs/btrfs/qgroup.c b/fs/btrfs/qgroup.c
index 75bb4af9..93e12c1 100644
--- a/fs/btrfs/qgroup.c
+++ b/fs/btrfs/qgroup.c
@@ -2198,7 +2198,6 @@ qgroup_rescan_leaf(struct btrfs_fs_info *fs_info, struct
btrfs_path *path,
int slot;
int ret;
- path->leave_spinning = 1;
mutex_lock(&fs_info->qgroup_rescan_lock);
ret = btrfs_search_slot_for_read(fs_info->extent_root,
&fs_info->qgroup_rescan_progress,
--
2.1.3
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