btrfs: fix lockdep warning with reclaim lock inversion

When encountering memory pressure, testers have run into the following lockdep warning. It was caused by __link_block_group calling kobject_add with the groups_sem held. kobject_add calls kvasprintf with GFP_KERNEL, which gets us into reclaim context. The kobject doesn't actually need to be added under the lock -- it just needs to ensure that it's only added for the first block group to be linked.

=========================================================
[ INFO: possible irq lock inversion dependency detected ]
3.14.0-rc8-default #1 Not tainted
---------------------------------------------------------
kswapd0/169 just changed the state of lock:
(&delayed_node->mutex){+.+.-.}, at: [<ffffffffa018baea>] __btrfs_release_delayed_node+0x3a/0x200 [btrfs]
but this lock took another, RECLAIM_FS-unsafe lock in the past:
(&found->groups_sem){+++++.}

and interrupts could create inverse lock ordering between them.

other info that might help us debug this:
Possible interrupt unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&found->groups_sem);
                               local_irq_disable();
                               lock(&delayed_node->mutex);
                               lock(&found->groups_sem);
  <Interrupt>
    lock(&delayed_node->mutex);

*** DEADLOCK ***
2 locks held by kswapd0/169:
#0: (shrinker_rwsem){++++..}, at: [<ffffffff81159e8a>] shrink_slab+0x3a/0x160 #1: (&type->s_umount_key#27){++++..}, at: [<ffffffff811bac6f>] grab_super_passive+0x3f/0x90

Signed-off-by Jeff Mahoney <[email protected]>

When encountering memory pressure, testers have run into the following lockdep warning. It was caused by __link_block_group calling kobject_add with the groups_sem held. kobject_add calls kvasprintf with GFP_KERNEL, which gets us into reclaim context. The kobject doesn't actually need to be added under the lock -- it just needs to ensure that it's only added for the first block group to be linked.

=========================================================
[ INFO: possible irq lock inversion dependency detected ]
3.14.0-rc8-default #1 Not tainted
---------------------------------------------------------
kswapd0/169 just changed the state of lock:
(&delayed_node->mutex){+.+.-.}, at: [<ffffffffa018baea>] __btrfs_release_delayed_node+0x3a/0x200 [btrfs]
but this lock took another, RECLAIM_FS-unsafe lock in the past:
(&found->groups_sem){+++++.}

and interrupts could create inverse lock ordering between them.

other info that might help us debug this:
Possible interrupt unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&found->groups_sem);
                               local_irq_disable();
                               lock(&delayed_node->mutex);
                               lock(&found->groups_sem);
  <Interrupt>
    lock(&delayed_node->mutex);

*** DEADLOCK ***
2 locks held by kswapd0/169:
#0: (shrinker_rwsem){++++..}, at: [<ffffffff81159e8a>] shrink_slab+0x3a/0x160 #1: (&type->s_umount_key#27){++++..}, at: [<ffffffff811bac6f>] grab_super_passive+0x3f/0x90

Signed-off-by Jeff Mahoney <[email protected]>

---
 fs/btrfs/extent-tree.c |   10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

fs/btrfs/extent-tree.c +7 -4

@@ -8343,9 +8343,15 @@ static void __link_block_group(struct bt
                               struct btrfs_block_group_cache *cache)
 {
        int index = get_block_group_index(cache);
+       bool first = false;
 
        down_write(&space_info->groups_sem);
-       if (list_empty(&space_info->block_groups[index])) {
+       if (list_empty(&space_info->block_groups[index]))
+               first = true;
+       list_add_tail(&cache->list, &space_info->block_groups[index]);
+       up_write(&space_info->groups_sem);
+
+       if (first) {
                struct kobject *kobj = &space_info->block_group_kobjs[index];
                int ret;
 

@@ -8357,8 +8363,6 @@ static void __link_block_group(struct bt
                        kobject_put(&space_info->kobj);
                }
        }
-       list_add_tail(&cache->list, &space_info->block_groups[index]);
-       up_write(&space_info->groups_sem);
 }
 
 static struct btrfs_block_group_cache *
 
 
--

Jeff Mahoney
SUSE Labs
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Quoted 31 lines · Jeff Mahoney

When encountering memory pressure, testers have run into the following lockdep warning. It was caused by __link_block_group calling kobject_add with the groups_sem held. kobject_add calls kvasprintf with GFP_KERNEL, which gets us into reclaim context. The kobject doesn't actually need to be added under the lock -- it just needs to ensure that it's only added for the first block group to be linked.

========================================================= [ INFO:
possible irq lock inversion dependency detected ] 3.14.0-rc8-default #1 Not tainted
---------------------------------------------------------
kswapd0/169 just changed the state of lock:
(&delayed_node->mutex){+.+.-.}, at: [<ffffffffa018baea>] __btrfs_release_delayed_node+0x3a/0x200 [btrfs] but this lock took another, RECLAIM_FS-unsafe lock in the past:
(&found->groups_sem){+++++.}

and interrupts could create inverse lock ordering between them.

other info that might help us debug this: Possible interrupt
unsafe locking scenario: CPU0 CPU1 ----
---- lock(&found->groups_sem); local_irq_disable(); lock(&delayed_node->mutex); lock(&found->groups_sem); <Interrupt> lock(&delayed_node->mutex);

*** DEADLOCK *** 2 locks held by kswapd0/169: #0:
(shrinker_rwsem){++++..}, at: [<ffffffff81159e8a>]

shrink_slab+0x3a/0x160 #1:  (&type->s_umount_key#27){++++..}, at:
[<ffffffff811bac6f>] grab_super_passive+0x3f/0x90

Quoted 1 line

Signed-off-by Jeff Mahoney <[email protected]>

Hi Jeff,

The same kind of problem happens when deleting the kobj. See the trace below, thanks.

[23510.196996] BTRFS: device fsid
6b4518c2-60e8-4990-8c6e-fb15054b1e46 devid 1 transid 4 /dev/sdd 
[23510.203212] BTRFS info (device sdd): disk space caching is
enabled [23510.203214] BTRFS: flagging fs with big metadata
feature [23510.227365] BTRFS: creating UUID tree [23661.587069] 
[23661.587073]
========================================================= 
[23661.587074] [ INFO: possible irq lock inversion dependency
detected ] [23661.587076] 3.13.0-fdm-btrfs-next-24+ #7 Not tainted 
[23661.587077]
--------------------------------------------------------- 
[23661.587078] kswapd0/42 just changed the state of lock: 
[23661.587079]  (&delayed_node->mutex){+.+.-.}, at: 

[<ffffffffa036d73c>] __btrfs_release_delayed_node+0x4c/0x1f0 [btrfs] [23661.587095] but this lock took another, RECLAIM_FS-unsafe lock in the past: [23661.587096] (sysfs_mutex){+.+.+.} [23661.587096] [23661.587096] and interrupts could create inverse lock ordering between them. [23661.587096]

[23661.587098] [23661.587098] other info that might help us debug
this: [23661.587099] Chain exists of: [23661.587099]
&delayed_node->mutex --> &found->groups_sem --> sysfs_mutex 
[23661.587099] [23661.587102]  Possible interrupt unsafe locking
scenario: [23661.587102] [23661.587103]        CPU0
CPU1 [23661.587103]        ----                    ---- 
[23661.587104]   lock(sysfs_mutex); [23661.587105]
local_irq_disable(); [23661.587106]
lock(&delayed_node->mutex); [23661.587107]
lock(&found->groups_sem); [23661.587108]   <Interrupt> 
[23661.587109]     lock(&delayed_node->mutex); [23661.587110] 
[23661.587110]  *** DEADLOCK *** [23661.587110] [23661.587111] 2

locks held by kswapd0/42: [23661.587112] #0:
(shrinker_rwsem){++++..}, at: [<ffffffff8114d0ec>] shrink_slab+0x3c/0x3a0 [23661.587117] #1:
(&type->s_umount_key#31){+++++.}, at: [<ffffffff811a43d4>] grab_super_passive+0x44/0x90 [23661.587122] [23661.587122] the shortest dependencies between 2nd lock and 1st lock: [23661.587126] -> (sysfs_mutex){+.+.+.} ops: 12918522 { [23661.587129] HARDIRQ-ON-W at: [23661.587130]

[<ffffffff81099900>] __lock_acquire+0x670/0x1e40 [23661.587133]
[<ffffffff8109b6e5>] lock_acquire+0x85/0x110 [23661.587134]
[<ffffffff816f7f36>] mutex_lock_nested+0x76/0x390 [23661.587137]
[<ffffffff8121f1b6>] sysfs_mount+0x166/0x210 [23661.587140]
[<ffffffff811a4d53>] mount_fs+0x43/0x1b0 [23661.587142]
[<ffffffff811c2403>] vfs_kern_mount+0x73/0x160 [23661.587144]
[<ffffffff811c2509>] kern_mount_data+0x19/0x30 [23661.587145]
[<ffffffff81f16082>] sysfs_init+0x55/0xb5 [23661.587148]
[<ffffffff81f13435>] mnt_init+0xcd/0x1d8 [23661.587149]
[<ffffffff81f130d7>] vfs_caches_init+0x99/0x11c [23661.587151]
[<ffffffff81eebe1e>] start_kernel+0x3ab/0x40c [23661.587154]
[<ffffffff81eeb579>] x86_64_start_reservations+0x2a/0x2c 
[23661.587155]                         [<ffffffff81eeb672>] 
x86_64_start_kernel+0xf7/0xfb [23661.587157]      SOFTIRQ-ON-W at: 
[23661.587158]                         [<ffffffff8109993c>] 
__lock_acquire+0x6ac/0x1e40 [23661.587160]
[<ffffffff8109b6e5>] lock_acquire+0x85/0x110 [23661.587162]
[<ffffffff816f7f36>] mutex_lock_nested+0x76/0x390 [23661.587164]
[<ffffffff8121f1b6>] sysfs_mount+0x166/0x210 [23661.587166]
[<ffffffff811a4d53>] mount_fs+0x43/0x1b0 [23661.587167]
[<ffffffff811c2403>] vfs_kern_mount+0x73/0x160 [23661.587169]
[<ffffffff811c2509>] kern_mount_data+0x19/0x30 [23661.587171]
[<ffffffff81f16082>] sysfs_init+0x55/0xb5 [23661.587173]
[<ffffffff81f13435>] mnt_init+0xcd/0x1d8 [23661.587174]
[<ffffffff81f130d7>] vfs_caches_init+0x99/0x11c [23661.587175]
[<ffffffff81eebe1e>] start_kernel+0x3ab/0x40c [23661.587177]
[<ffffffff81eeb579>] x86_64_start_reservations+0x2a/0x2c 
[23661.587178]                         [<ffffffff81eeb672>] 
x86_64_start_kernel+0xf7/0xfb [23661.587180]      RECLAIM_FS-ON-W
at: [23661.587181]                            [<ffffffff8109c039>] 
mark_held_locks+0xb9/0x140 [23661.587183]
[<ffffffff8109c7c5>] lockdep_trace_alloc+0x65/0xd0 [23661.587185]
[<ffffffff8118e7e3>] kmem_cache_alloc+0x33/0x1e0 [23661.587187]
[<ffffffff811bcc51>] alloc_inode+0x61/0xa0 [23661.587190]
[<ffffffff811be178>] iget_locked+0xd8/0x1d0 [23661.587192]
[<ffffffff8121b54a>] sysfs_get_inode+0x1a/0x170 [23661.587193]
[<ffffffff8121f1c5>] sysfs_mount+0x175/0x210 [23661.587195]
[<ffffffff811a4d53>] mount_fs+0x43/0x1b0 [23661.587196]
[<ffffffff811c2403>] vfs_kern_mount+0x73/0x160 [23661.587198]
[<ffffffff811c4d49>] do_mount+0x259/0xb70 [23661.587199]
[<ffffffff811c594e>] SyS_mount+0x8e/0xe0 [23661.587201]
[<ffffffff81703212>] system_call_fastpath+0x16/0x1b [23661.587204]
INITIAL USE at: [23661.587204]
[<ffffffff810995bd>] __lock_acquire+0x32d/0x1e40 [23661.587206]
[<ffffffff8109b6e5>] lock_acquire+0x85/0x110 [23661.587207]
[<ffffffff816f7f36>] mutex_lock_nested+0x76/0x390 [23661.587209]
[<ffffffff8121f1b6>] sysfs_mount+0x166/0x210 [23661.587211]
[<ffffffff811a4d53>] mount_fs+0x43/0x1b0 [23661.587212]
[<ffffffff811c2403>] vfs_kern_mount+0x73/0x160 [23661.587213]
[<ffffffff811c2509>] kern_mount_data+0x19/0x30 [23661.587215]
[<ffffffff81f16082>] sysfs_init+0x55/0xb5 [23661.587216]
[<ffffffff81f13435>] mnt_init+0xcd/0x1d8 [23661.587217]
[<ffffffff81f130d7>] vfs_caches_init+0x99/0x11c [23661.587218]
[<ffffffff81eebe1e>] start_kernel+0x3ab/0x40c [23661.587220]
[<ffffffff81eeb579>] x86_64_start_reservations+0x2a/0x2c 
[23661.587221]                        [<ffffffff81eeb672>] 
x86_64_start_kernel+0xf7/0xfb [23661.587222]    } [23661.587223]
... key      at: [<ffffffff81c79918>] sysfs_mutex+0x78/0xc0 
[23661.587226]    ... acquired at: [23661.587227]
[<ffffffff8109b6e5>] lock_acquire+0x85/0x110 [23661.587228]
[<ffffffff816f7f36>] mutex_lock_nested+0x76/0x390 [23661.587230]
[<ffffffff8121defe>] sysfs_addrm_start+0x1e/0x20 [23661.587232]
[<ffffffff8121e59a>] sysfs_remove+0x1a/0x40 [23661.587233]
[<ffffffff8121e6c3>] sysfs_remove_dir+0x53/0x80 [23661.587234]
[<ffffffff81361d11>] kobject_del+0x21/0x50 [23661.587237]
[<ffffffffa030b060>] btrfs_remove_block_group+0x420/0x540 [btrfs] 
[23661.587246]    [<ffffffffa034087b>] 
btrfs_relocate_chunk.isra.61+0x60b/0x760 [btrfs] [23661.587254]
[<ffffffffa034497f>] btrfs_balance+0x86f/0xfd0 [btrfs] 
[23661.587262]    [<ffffffffa034cb45>]
btrfs_ioctl_balance+0x1c5/0x530 [btrfs] [23661.587269]
[<ffffffffa034fcfc>] btrfs_ioctl+0x68c/0x28a0 [btrfs] 
[23661.587276]    [<ffffffff811b4938>] do_vfs_ioctl+0x88/0x570 
[23661.587278]    [<ffffffff811b4eb1>] SyS_ioctl+0x91/0xb0 
[23661.587279]    [<ffffffff81703212>]
system_call_fastpath+0x16/0x1b [23661.587281] [23661.587282]  ->
(&found->groups_sem){++++..} ops: 897759 { [23661.587284]
HARDIRQ-ON-W at: [23661.587285]
[<ffffffff81099900>] __lock_acquire+0x670/0x1e40 [23661.587287]
[<ffffffff8109b6e5>] lock_acquire+0x85/0x110 [23661.587288]
[<ffffffff816f8a81>] down_write+0x61/0xc0 [23661.587290]
[<ffffffffa0306004>] __link_block_group+0x44/0x100 [btrfs] 
[23661.587295]                       [<ffffffffa0309bf6>] 
btrfs_read_block_groups+0x306/0x650 [btrfs] [23661.587301]
[<ffffffffa0318376>] open_ctree+0x1676/0x2070 [btrfs] 
[23661.587308]                       [<ffffffffa02ede54>] 
btrfs_mount+0x6b4/0x910 [btrfs] [23661.587312]
[<ffffffff811a4d53>] mount_fs+0x43/0x1b0 [23661.587313]
[<ffffffff811c2403>] vfs_kern_mount+0x73/0x160 [23661.587315]
[<ffffffff811c4d49>] do_mount+0x259/0xb70 [23661.587316]
[<ffffffff811c594e>] SyS_mount+0x8e/0xe0 [23661.587318]
[<ffffffff81703212>] system_call_fastpath+0x16/0x1b [23661.587320]
HARDIRQ-ON-R at: [23661.587320]
[<ffffffff810997bd>] __lock_acquire+0x52d/0x1e40 [23661.587322]
[<ffffffff8109b6e5>] lock_acquire+0x85/0x110 [23661.587323]
[<ffffffff816f8b31>] down_read+0x51/0xa0 [23661.587325]
[<ffffffffa0314098>] 
btrfs_calc_num_tolerated_disk_barrier_failures+0x118/0x1e0 [btrfs] 
[23661.587331]                       [<ffffffffa0318386>] 
open_ctree+0x1686/0x2070 [btrfs] [23661.587337]
[<ffffffffa02ede54>] btrfs_mount+0x6b4/0x910 [btrfs] [23661.587341]
[<ffffffff811a4d53>] mount_fs+0x43/0x1b0 [23661.587342]
[<ffffffff811c2403>] vfs_kern_mount+0x73/0x160 [23661.587344]
[<ffffffff811c4d49>] do_mount+0x259/0xb70 [23661.587345]
[<ffffffff811c594e>] SyS_mount+0x8e/0xe0 [23661.587346]
[<ffffffff81703212>] system_call_fastpath+0x16/0x1b [23661.587348]
SOFTIRQ-ON-W at: [23661.587349]
[<ffffffff8109993c>] __lock_acquire+0x6ac/0x1e40 [23661.587350]
[<ffffffff8109b6e5>] lock_acquire+0x85/0x110 [23661.587352]
[<ffffffff816f8a81>] down_write+0x61/0xc0 [23661.587353]
[<ffffffffa0306004>] __link_block_group+0x44/0x100 [btrfs] 
[23661.587359]                       [<ffffffffa0309bf6>] 
btrfs_read_block_groups+0x306/0x650 [btrfs] [23661.587364]
[<ffffffffa0318376>] open_ctree+0x1676/0x2070 [btrfs] 
[23661.587370]                       [<ffffffffa02ede54>] 
btrfs_mount+0x6b4/0x910 [btrfs] [23661.587374]
[<ffffffff811a4d53>] mount_fs+0x43/0x1b0 [23661.587375]
[<ffffffff811c2403>] vfs_kern_mount+0x73/0x160 [23661.587376]
[<ffffffff811c4d49>] do_mount+0x259/0xb70 [23661.587378]
[<ffffffff811c594e>] SyS_mount+0x8e/0xe0 [23661.587379]
[<ffffffff81703212>] system_call_fastpath+0x16/0x1b [23661.587381]
SOFTIRQ-ON-R at: [23661.587382]
[<ffffffff8109993c>] __lock_acquire+0x6ac/0x1e40 [23661.587383]
[<ffffffff8109b6e5>] lock_acquire+0x85/0x110 [23661.587384]
[<ffffffff816f8b31>] down_read+0x51/0xa0 [23661.587386]
[<ffffffffa0314098>] 
btrfs_calc_num_tolerated_disk_barrier_failures+0x118/0x1e0 [btrfs] 
[23661.587392]                       [<ffffffffa0318386>] 
open_ctree+0x1686/0x2070 [btrfs] [23661.587397]
[<ffffffffa02ede54>] btrfs_mount+0x6b4/0x910 [btrfs] [23661.587401]
[<ffffffff811a4d53>] mount_fs+0x43/0x1b0 [23661.587402]
[<ffffffff811c2403>] vfs_kern_mount+0x73/0x160 [23661.587404]
[<ffffffff811c4d49>] do_mount+0x259/0xb70 [23661.587405]
[<ffffffff811c594e>] SyS_mount+0x8e/0xe0 [23661.587406]
[<ffffffff81703212>] system_call_fastpath+0x16/0x1b [23661.587408]
INITIAL USE at: [23661.587409]
[<ffffffff810995bd>] __lock_acquire+0x32d/0x1e40 [23661.587410]
[<ffffffff8109b6e5>] lock_acquire+0x85/0x110 [23661.587412]
[<ffffffff816f8a81>] down_write+0x61/0xc0 [23661.587413]
[<ffffffffa0306004>] __link_block_group+0x44/0x100 [btrfs] 
[23661.587418]                      [<ffffffffa0309bf6>] 
btrfs_read_block_groups+0x306/0x650 [btrfs] [23661.587424]
[<ffffffffa0318376>] open_ctree+0x1676/0x2070 [btrfs] 
[23661.587429]                      [<ffffffffa02ede54>] 
btrfs_mount+0x6b4/0x910 [btrfs] [23661.587433]
[<ffffffff811a4d53>] mount_fs+0x43/0x1b0 [23661.587435]
[<ffffffff811c2403>] vfs_kern_mount+0x73/0x160 [23661.587436]
[<ffffffff811c4d49>] do_mount+0x259/0xb70 [23661.587437]
[<ffffffff811c594e>] SyS_mount+0x8e/0xe0 [23661.587439]
[<ffffffff81703212>] system_call_fastpath+0x16/0x1b [23661.587441]
} [23661.587441]   ... key      at: [<ffffffffa03b5ab8>] 
__key.40358+0x0/0xfffffffffffe2548 [btrfs] [23661.587447]   ...
acquired at: [23661.587448]    [<ffffffff8109b6e5>]
lock_acquire+0x85/0x110 [23661.587449]    [<ffffffff816f8b31>]
down_read+0x51/0xa0 [23661.587451]    [<ffffffffa0306891>]
find_free_extent+0x7d1/0xc30 [btrfs] [23661.587456]
[<ffffffffa0306d98>] btrfs_reserve_extent+0xa8/0x140 [btrfs] 
[23661.587461]    [<ffffffffa0308236>]
btrfs_alloc_free_block+0xe6/0x460 [btrfs] [23661.587467]
[<ffffffffa02f6d30>] split_leaf+0x1b0/0x770 [btrfs] [23661.587471]
[<ffffffffa02f7f23>] btrfs_search_slot+0x963/0x9e0 [btrfs] 
[23661.587476]    [<ffffffffa02f9658>] 
btrfs_insert_empty_items+0x78/0xd0 [btrfs] [23661.587481]
[<ffffffffa036db37>] btrfs_insert_delayed_items+0x87/0x420 [btrfs] 
[23661.587489]    [<ffffffffa036e8c2>] 
btrfs_async_run_delayed_root+0xf2/0x200 [btrfs] [23661.587496]
[<ffffffffa0349fc7>] normal_work_helper+0x137/0x2c0 [btrfs] 
[23661.587503]    [<ffffffff810681f5>]
process_one_work+0x1f5/0x530 [23661.587505]    [<ffffffff810689dc>]
worker_thread+0x11c/0x370 [23661.587506]    [<ffffffff810703c6>]
kthread+0xf6/0x110 [23661.587508]    [<ffffffff8170316c>]
ret_from_fork+0x7c/0xb0 [23661.587510] [23661.587510] ->
(&delayed_node->mutex){+.+.-.} ops: 5556073 { [23661.587513]
HARDIRQ-ON-W at: [23661.587514]
[<ffffffff81099900>] __lock_acquire+0x670/0x1e40 [23661.587515]
[<ffffffff8109b6e5>] lock_acquire+0x85/0x110 [23661.587516]
[<ffffffff816f7f36>] mutex_lock_nested+0x76/0x390 [23661.587518]
[<ffffffffa036f7bf>] btrfs_delayed_update_inode+0x4f/0x500 [btrfs] 
[23661.587525]                     [<ffffffffa0321107>] 
btrfs_update_inode+0x67/0xf0 [btrfs] [23661.587532]
[<ffffffffa03293a2>] btrfs_mkdir+0x182/0x1e0 [btrfs] [23661.587539]
[<ffffffff811b03ca>] vfs_mkdir+0xca/0x170 [23661.587541]
[<ffffffff811b2a8b>] SyS_mkdir+0xab/0xf0 [23661.587542]
[<ffffffff81703212>] system_call_fastpath+0x16/0x1b [23661.587544]
SOFTIRQ-ON-W at: [23661.587544]
[<ffffffff8109993c>] __lock_acquire+0x6ac/0x1e40 [23661.587546]
[<ffffffff8109b6e5>] lock_acquire+0x85/0x110 [23661.587547]
[<ffffffff816f7f36>] mutex_lock_nested+0x76/0x390 [23661.587549]
[<ffffffffa036f7bf>] btrfs_delayed_update_inode+0x4f/0x500 [btrfs] 
[23661.587556]                     [<ffffffffa0321107>] 
btrfs_update_inode+0x67/0xf0 [btrfs] [23661.587562]
[<ffffffffa03293a2>] btrfs_mkdir+0x182/0x1e0 [btrfs] [23661.587568]
[<ffffffff811b03ca>] vfs_mkdir+0xca/0x170 [23661.587570]
[<ffffffff811b2a8b>] SyS_mkdir+0xab/0xf0 [23661.587571]
[<ffffffff81703212>] system_call_fastpath+0x16/0x1b [23661.587573]
IN-RECLAIM_FS-W at: [23661.587574]
[<ffffffff81099838>] __lock_acquire+0x5a8/0x1e40 [23661.587575]
[<ffffffff8109b6e5>] lock_acquire+0x85/0x110 [23661.587577]
[<ffffffff816f7f36>] mutex_lock_nested+0x76/0x390 [23661.587578]
[<ffffffffa036d73c>] __btrfs_release_delayed_node+0x4c/0x1f0
[btrfs] [23661.587585]                        [<ffffffffa036ed04>] 
btrfs_remove_delayed_node+0x24/0x30 [btrfs] [23661.587592]
[<ffffffffa032650d>] btrfs_evict_inode+0x1cd/0x520 [btrfs] 
[23661.587599]                        [<ffffffff811bdd17>]
evict+0xa7/0x1a0 [23661.587601]
[<ffffffff811bde4e>] dispose_list+0x3e/0x60 [23661.587602]
[<ffffffff811bed3c>] prune_icache_sb+0x4c/0x60 [23661.587604]
[<ffffffff811a4641>] super_cache_scan+0x111/0x170 [23661.587605]
[<ffffffff8114d28a>] shrink_slab+0x1da/0x3a0 [23661.587608]
[<ffffffff81150905>] balance_pgdat+0x3d5/0x5e0 [23661.587609]
[<ffffffff81150cba>] kswapd+0x1aa/0x4a0 [23661.587610]
[<ffffffff810703c6>] kthread+0xf6/0x110 [23661.587611]
[<ffffffff8170316c>] ret_from_fork+0x7c/0xb0 [23661.587613]
INITIAL USE at: [23661.587614]
[<ffffffff810995bd>] __lock_acquire+0x32d/0x1e40 [23661.587615]
[<ffffffff8109b6e5>] lock_acquire+0x85/0x110 [23661.587617]
[<ffffffff816f7f36>] mutex_lock_nested+0x76/0x390 [23661.587618]
[<ffffffffa036f7bf>] btrfs_delayed_update_inode+0x4f/0x500 [btrfs] 
[23661.587625]                    [<ffffffffa0321107>] 
btrfs_update_inode+0x67/0xf0 [btrfs] [23661.587631]
[<ffffffffa03293a2>] btrfs_mkdir+0x182/0x1e0 [btrfs] [23661.587638]
[<ffffffff811b03ca>] vfs_mkdir+0xca/0x170 [23661.587640]
[<ffffffff811b2a8b>] SyS_mkdir+0xab/0xf0 [23661.587641]
[<ffffffff81703212>] system_call_fastpath+0x16/0x1b [23661.587643]
} [23661.587643]  ... key      at: [<ffffffffa03b9a88>] 
__key.35650+0x0/0xfffffffffffde578 [btrfs] [23661.587649]  ...
acquired at: [23661.587649]    [<ffffffff810988f6>]
check_usage_forwards+0x146/0x150 [23661.587651]
[<ffffffff81099156>] mark_lock+0x186/0x2c0 [23661.587652]
[<ffffffff81099838>] __lock_acquire+0x5a8/0x1e40 [23661.587653]
[<ffffffff8109b6e5>] lock_acquire+0x85/0x110 [23661.587655]
[<ffffffff816f7f36>] mutex_lock_nested+0x76/0x390 [23661.587656]
[<ffffffffa036d73c>] __btrfs_release_delayed_node+0x4c/0x1f0
[btrfs] [23661.587663]    [<ffffffffa036ed04>] 
btrfs_remove_delayed_node+0x24/0x30 [btrfs] [23661.587670]
[<ffffffffa032650d>] btrfs_evict_inode+0x1cd/0x520 [btrfs] 
[23661.587676]    [<ffffffff811bdd17>] evict+0xa7/0x1a0 
[23661.587678]    [<ffffffff811bde4e>] dispose_list+0x3e/0x60 
[23661.587679]    [<ffffffff811bed3c>] prune_icache_sb+0x4c/0x60 
[23661.587681]    [<ffffffff811a4641>]
super_cache_scan+0x111/0x170 [23661.587682]    [<ffffffff8114d28a>]
shrink_slab+0x1da/0x3a0 [23661.587684]    [<ffffffff81150905>]
balance_pgdat+0x3d5/0x5e0 [23661.587685]    [<ffffffff81150cba>]
kswapd+0x1aa/0x4a0 [23661.587686]    [<ffffffff810703c6>]
kthread+0xf6/0x110 [23661.587687]    [<ffffffff8170316c>]
ret_from_fork+0x7c/0xb0 [23661.587689] [23661.587690] 
[23661.587690] stack backtrace: [23661.587692] CPU: 1 PID: 42 Comm:
kswapd0 Not tainted 3.13.0-fdm-btrfs-next-24+ #7 [23661.587693]
Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011 [23661.587694]

ffffffff825db980 ffff8801f5e176a8 ffffffff816f1da6 0000000000000007 [23661.587696] ffffffff825db980 ffff8801f5e176f8 ffffffff816ed6b8 ffffffff825db980 [23661.587698] ffff880213f2ac40 ffff8801f5e1770c 0000000000000000 ffff880213f2ac40 [23661.587700]

Call Trace: [23661.587702]  [<ffffffff816f1da6>]
dump_stack+0x4e/0x68 [23661.587705]  [<ffffffff816ed6b8>]
print_irq_inversion_bug.part.38+0x1b0/0x1bf [23661.587706]
[<ffffffff810988f6>] check_usage_forwards+0x146/0x150 
[23661.587708]  [<ffffffff810987b0>] ?
check_usage_backwards+0x150/0x150 [23661.587710]
[<ffffffff81099156>] mark_lock+0x186/0x2c0 [23661.587711]
[<ffffffff81099838>] __lock_acquire+0x5a8/0x1e40 [23661.587713]
[<ffffffff81095b87>] ? __bfs+0x157/0x250 [23661.587714]
[<ffffffff8109631b>] ? 
add_lock_to_list.isra.26.constprop.42+0x7b/0xc0 [23661.587716]
[<ffffffff8109a5ed>] ? __lock_acquire+0x135d/0x1e40 [23661.587718]
[<ffffffff816fa94f>] ? _raw_spin_unlock_irqrestore+0x3f/0x70 
[23661.587719]  [<ffffffff8109b6e5>] lock_acquire+0x85/0x110 
[23661.587726]  [<ffffffffa036d73c>] ? 
__btrfs_release_delayed_node+0x4c/0x1f0 [btrfs] [23661.587729]
[<ffffffff816f7f36>] mutex_lock_nested+0x76/0x390 [23661.587735]
[<ffffffffa036d73c>] ? __btrfs_release_delayed_node+0x4c/0x1f0
[btrfs] [23661.587737]  [<ffffffff81095d08>] ?
trace_hardirqs_off_caller+0x28/0xd0 [23661.587744]
[<ffffffffa036d73c>] ? __btrfs_release_delayed_node+0x4c/0x1f0
[btrfs] [23661.587747]  [<ffffffff81082dff>] ?
local_clock+0x4f/0x60 [23661.587754]  [<ffffffffa036d73c>] 
__btrfs_release_delayed_node+0x4c/0x1f0 [btrfs] [23661.587761]
[<ffffffffa036ed04>] btrfs_remove_delayed_node+0x24/0x30 [btrfs] 
[23661.587767]  [<ffffffffa032650d>] btrfs_evict_inode+0x1cd/0x520
[btrfs] [23661.587769]  [<ffffffff816fa9ab>] ?
_raw_spin_unlock+0x2b/0x40 [23661.587771]  [<ffffffff811bdd17>]
evict+0xa7/0x1a0 [23661.587773]  [<ffffffff811bde4e>]
dispose_list+0x3e/0x60 [23661.587775]  [<ffffffff811bed3c>]
prune_icache_sb+0x4c/0x60 [23661.587776]  [<ffffffff811a4641>]
super_cache_scan+0x111/0x170 [23661.587778]  [<ffffffff8114d28a>]
shrink_slab+0x1da/0x3a0 [23661.587780]  [<ffffffff81150905>]
balance_pgdat+0x3d5/0x5e0 [23661.587782]  [<ffffffff81150cba>]
kswapd+0x1aa/0x4a0 [23661.587784]  [<ffffffff8108e8e0>] ?
bit_waitqueue+0xc0/0xc0 [23661.587785]  [<ffffffff81150b10>] ?
balance_pgdat+0x5e0/0x5e0 [23661.587787]  [<ffffffff810703c6>]
kthread+0xf6/0x110 [23661.587788]  [<ffffffff810702d0>] ?
kthread_create_on_node+0x250/0x250 [23661.587790]
[<ffffffff8170316c>] ret_from_fork+0x7c/0xb0 [23661.587792]
[<ffffffff810702d0>] ? kthread_create_on_node+0x250/0x250

Quoted 21 lines

--- fs/btrfs/extent-tree.c | 10 +++++++--- 1 file changed, 7
insertions(+), 3 deletions(-)

--- a/fs/btrfs/extent-tree.c +++ b/fs/btrfs/extent-tree.c @@ -8343,9 +8343,15 @@ static void __link_block_group(struct bt struct btrfs_block_group_cache *cache) { int index =
get_block_group_index(cache); + bool first = false;

down_write(&space_info->groups_sem); - if
(list_empty(&space_info->block_groups[index])) { + if
(list_empty(&space_info->block_groups[index])) +
first = true; + list_add_tail(&cache->list,
&space_info->block_groups[index]); +
up_write(&space_info->groups_sem); + + if (first) { struct
kobject *kobj = &space_info->block_group_kobjs[index]; int ret;

(quoted diff) +0 -0

@@ -8357,8 +8363,6 @@ static void __link_block_group(struct bt 

kobject_put(&space_info->kobj); } } - list_add_tail(&cache->list, &space_info->block_groups[index]); - up_write(&space_info->groups_sem); }

Quoted 7 lines

static struct btrfs_block_group_cache *

-- Jeff Mahoney SUSE Labs -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to [email protected] More majordomo info at
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