When running generic/475, we may get the following warning in the dmesg.
[ 6902.102154] WARNING: CPU: 3 PID: 18013 at fs/btrfs/extent-tree.c:9776
btrfs_free_block_groups+0x2af/0x3b0 [btrfs]
[ 6902.104886] Modules linked in: btrfs(O) xor zstd_decompress zstd_compress
xxhash raid6_pq efivarfs xfs nvme nvme_core [last unloaded: btrfs]
[ 6902.109160] CPU: 3 PID: 18013 Comm: umount Tainted: G W O
4.19.0-rc8+ #8
[ 6902.110971] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0
02/06/2015
[ 6902.112857] RIP: 0010:btrfs_free_block_groups+0x2af/0x3b0 [btrfs]
[ 6902.114377] Code: c6 48 89 04 24 48 8b 83 50 17 00 00 48 39 c6 0f 84 ab 00
00 00 4c 8b ab 50 17 00 00 49 83 bd 50 ff ff ff 00 0f 84 b4 00 00 00 <0f> 0b 31
c9 49 8d b5 f8 fe ff ff 31 d2 48
89 df e8 fc 76 ff ff 49
[ 6902.118921] RSP: 0018:ffffc9000459bdb0 EFLAGS: 00010286
[ 6902.120315] RAX: ffff880175050bb0 RBX: ffff8801124a8000 RCX: 0000000000170007
[ 6902.121969] RDX: 0000000000000002 RSI: 0000000000170007 RDI: ffffffff8125fb74
[ 6902.123716] RBP: ffff880175055d10 R08: 0000000000000000 R09: 0000000000000000
[ 6902.125417] R10: 0000000000000000 R11: 0000000000000000 R12: ffff880175055d88
[ 6902.127129] R13: ffff880175050bb0 R14: 0000000000000000 R15: dead000000000100
[ 6902.129060] FS: 00007f4507223780(0000) GS:ffff88017ba00000(0000)
knlGS:0000000000000000
[ 6902.130996] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 6902.132558] CR2: 00005623599cac78 CR3: 000000014b700001 CR4: 00000000003606e0
[ 6902.134270] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[ 6902.135981] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[ 6902.137836] Call Trace:
[ 6902.138939] close_ctree+0x171/0x330 [btrfs]
[ 6902.140181] ? kthread_stop+0x146/0x1f0
[ 6902.141277] generic_shutdown_super+0x6c/0x100
[ 6902.142517] kill_anon_super+0x14/0x30
[ 6902.143554] btrfs_kill_super+0x13/0x100 [btrfs]
[ 6902.144790] deactivate_locked_super+0x2f/0x70
[ 6902.146014] cleanup_mnt+0x3b/0x70
[ 6902.147020] task_work_run+0x9e/0xd0
[ 6902.148036] do_syscall_64+0x470/0x600
[ 6902.149142] ? trace_hardirqs_off_thunk+0x1a/0x1c
[ 6902.150375] entry_SYSCALL_64_after_hwframe+0x49/0xbe
[ 6902.151640] RIP: 0033:0x7f45077a6a7b
[ 6902.152782] Code: 23 0c 00 f7 d8 64 89 01 48 83 c8 ff c3 66 90 f3 0f 1e fa
31 f6 e9 05 00 00 00 90 0f 1f 40 00 f3 0f 1e fa b8 a6 00 00 00 0f 05 <48> 3d 01
f0 ff ff 73 01 c3 48 8b 0d b5 23
0c 00 f7 d8 64 89 01 48
[ 6902.157324] RSP: 002b:00007ffd589f3e68 EFLAGS: 00000246 ORIG_RAX:
00000000000000a6
[ 6902.159187] RAX: 0000000000000000 RBX: 000055e8eec732b0 RCX: 00007f45077a6a7b
[ 6902.160834] RDX: 0000000000000001 RSI: 0000000000000000 RDI: 000055e8eec73490
[ 6902.162526] RBP: 0000000000000000 R08: 000055e8eec734b0 R09: 00007ffd589f26c0
[ 6902.164141] R10: 0000000000000000 R11: 0000000000000246 R12: 000055e8eec73490
[ 6902.165815] R13: 00007f4507ac61a4 R14: 0000000000000000 R15: 00007ffd589f40d8
[ 6902.167553] irq event stamp: 0
[ 6902.168998] hardirqs last enabled at (0): [<0000000000000000>]
(null)
[ 6902.170731] hardirqs last disabled at (0): [<ffffffff810cd810>]
copy_process.part.55+0x3b0/0x1f00
[ 6902.172773] softirqs last enabled at (0): [<ffffffff810cd810>]
copy_process.part.55+0x3b0/0x1f00
[ 6902.174671] softirqs last disabled at (0): [<0000000000000000>]
(null)
[ 6902.176407] ---[ end trace 463138c2986b275c ]---
[ 6902.177636] BTRFS info (device dm-3): space_info 4 has 273465344 free, is
not full
[ 6902.179453] BTRFS info (device dm-3): space_info total=276824064,
used=4685824, pinned=18446744073708158976, reserved=0, may_use=0, readonly=65536
^^^
obviously underflow
When transaction_kthread is running cleanup_transaction(), another
fsstress is running btrfs_commit_transaction(). The
btrfs_finish_extent_commit() may get the same range as
btrfs_destroy_pinned_extent() got, which causes the pinned underflow.
Signed-off-by: Lu Fengqi <lufq.f...@cn.fujitsu.com>
---
fs/btrfs/disk-io.c | 12 +++++++++++-
1 file changed, 11 insertions(+), 1 deletion(-)
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index b0ab41da91d1..00ee5e37e989 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -4359,13 +4359,23 @@ static int btrfs_destroy_pinned_extent(struct
btrfs_fs_info *fs_info,
unpin = pinned_extents;
again:
while (1) {
+ /*
+ * The btrfs_finish_extent_commit() may get the same range as
+ * ours between find_first_extent_bit and clear_extent_dirty.
+ * Hence, hold the unused_bg_unpin_mutex to avoid double unpin
+ * the same extent range.
+ */
+ mutex_lock(&fs_info->unused_bg_unpin_mutex);
ret = find_first_extent_bit(unpin, 0, &start, &end,
EXTENT_DIRTY, NULL);
- if (ret)
+ if (ret) {
+ mutex_unlock(&fs_info->unused_bg_unpin_mutex);
break;
+ }
clear_extent_dirty(unpin, start, end);
btrfs_error_unpin_extent_range(fs_info, start, end);
+ mutex_unlock(&fs_info->unused_bg_unpin_mutex);
cond_resched();
}
--
2.19.1
