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0ccd05285e
linux/fs/btrfs
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Anand Jain 0ccd05285e btrfs: fix a possible umount deadlock 
btrfs_show_devname() is using the device_list_mutex, sometimes
a call to blkdev_put() leads vfs calling into this func. So
call blkdev_put() outside of device_list_mutex, as of now.

[  983.284212] ======================================================
[  983.290401] [ INFO: possible circular locking dependency detected ]
[  983.296677] 4.8.0-rc5-ceph-00023-g1b39cec2 #1 Not tainted
[  983.302081] -------------------------------------------------------
[  983.308357] umount/21720 is trying to acquire lock:
[  983.313243]  (&bdev->bd_mutex){+.+.+.}, at: [<ffffffff9128ec51>] blkdev_put+0x31/0x150
[  983.321264]
[  983.321264] but task is already holding lock:
[  983.327101]  (&fs_devs->device_list_mutex){+.+...}, at: [<ffffffffc033d6f6>] __btrfs_close_devices+0x46/0x200 [btrfs]
[  983.337839]
[  983.337839] which lock already depends on the new lock.
[  983.337839]
[  983.346024]
[  983.346024] the existing dependency chain (in reverse order) is:
[  983.353512]
-> #4 (&fs_devs->device_list_mutex){+.+...}:
[  983.359096]        [<ffffffff910dfd0c>] lock_acquire+0x1bc/0x1f0
[  983.365143]        [<ffffffff91823125>] mutex_lock_nested+0x65/0x350
[  983.371521]        [<ffffffffc02d8116>] btrfs_show_devname+0x36/0x1f0 [btrfs]
[  983.378710]        [<ffffffff9129523e>] show_vfsmnt+0x4e/0x150
[  983.384593]        [<ffffffff9126ffc7>] m_show+0x17/0x20
[  983.389957]        [<ffffffff91276405>] seq_read+0x2b5/0x3b0
[  983.395669]        [<ffffffff9124c808>] __vfs_read+0x28/0x100
[  983.401464]        [<ffffffff9124eb3b>] vfs_read+0xab/0x150
[  983.407080]        [<ffffffff9124ec32>] SyS_read+0x52/0xb0
[  983.412609]        [<ffffffff91825fc0>] entry_SYSCALL_64_fastpath+0x23/0xc1
[  983.419617]
-> #3 (namespace_sem){++++++}:
[  983.424024]        [<ffffffff910dfd0c>] lock_acquire+0x1bc/0x1f0
[  983.430074]        [<ffffffff918239e9>] down_write+0x49/0x80
[  983.435785]        [<ffffffff91272457>] lock_mount+0x67/0x1c0
[  983.441582]        [<ffffffff91272ab2>] do_add_mount+0x32/0xf0
[  983.447458]        [<ffffffff9127363a>] finish_automount+0x5a/0xc0
[  983.453682]        [<ffffffff91259513>] follow_managed+0x1b3/0x2a0
[  983.459912]        [<ffffffff9125b750>] lookup_fast+0x300/0x350
[  983.465875]        [<ffffffff9125d6e7>] path_openat+0x3a7/0xaa0
[  983.471846]        [<ffffffff9125ef75>] do_filp_open+0x85/0xe0
[  983.477731]        [<ffffffff9124c41c>] do_sys_open+0x14c/0x1f0
[  983.483702]        [<ffffffff9124c4de>] SyS_open+0x1e/0x20
[  983.489240]        [<ffffffff91825fc0>] entry_SYSCALL_64_fastpath+0x23/0xc1
[  983.496254]
-> #2 (&sb->s_type->i_mutex_key#3){+.+.+.}:
[  983.501798]        [<ffffffff910dfd0c>] lock_acquire+0x1bc/0x1f0
[  983.507855]        [<ffffffff918239e9>] down_write+0x49/0x80
[  983.513558]        [<ffffffff91366237>] start_creating+0x87/0x100
[  983.519703]        [<ffffffff91366647>] debugfs_create_dir+0x17/0x100
[  983.526195]        [<ffffffff911df153>] bdi_register+0x93/0x210
[  983.532165]        [<ffffffff911df313>] bdi_register_owner+0x43/0x70
[  983.538570]        [<ffffffff914080fb>] device_add_disk+0x1fb/0x450
[  983.544888]        [<ffffffff91580226>] loop_add+0x1e6/0x290
[  983.550596]        [<ffffffff91fec358>] loop_init+0x10b/0x14f
[  983.556394]        [<ffffffff91002207>] do_one_initcall+0xa7/0x180
[  983.562618]        [<ffffffff91f932e0>] kernel_init_freeable+0x1cc/0x266
[  983.569370]        [<ffffffff918174be>] kernel_init+0xe/0x100
[  983.575166]        [<ffffffff9182620f>] ret_from_fork+0x1f/0x40
[  983.581131]
-> #1 (loop_index_mutex){+.+.+.}:
[  983.585801]        [<ffffffff910dfd0c>] lock_acquire+0x1bc/0x1f0
[  983.591858]        [<ffffffff91823125>] mutex_lock_nested+0x65/0x350
[  983.598256]        [<ffffffff9157ed3f>] lo_open+0x1f/0x60
[  983.603704]        [<ffffffff9128eec3>] __blkdev_get+0x123/0x400
[  983.609757]        [<ffffffff9128f4ea>] blkdev_get+0x34a/0x350
[  983.615639]        [<ffffffff9128f554>] blkdev_open+0x64/0x80
[  983.621428]        [<ffffffff9124aff6>] do_dentry_open+0x1c6/0x2d0
[  983.627651]        [<ffffffff9124c029>] vfs_open+0x69/0x80
[  983.633181]        [<ffffffff9125db74>] path_openat+0x834/0xaa0
[  983.639152]        [<ffffffff9125ef75>] do_filp_open+0x85/0xe0
[  983.645035]        [<ffffffff9124c41c>] do_sys_open+0x14c/0x1f0
[  983.650999]        [<ffffffff9124c4de>] SyS_open+0x1e/0x20
[  983.656535]        [<ffffffff91825fc0>] entry_SYSCALL_64_fastpath+0x23/0xc1
[  983.663541]
-> #0 (&bdev->bd_mutex){+.+.+.}:
[  983.668107]        [<ffffffff910def43>] __lock_acquire+0x1003/0x17b0
[  983.674510]        [<ffffffff910dfd0c>] lock_acquire+0x1bc/0x1f0
[  983.680561]        [<ffffffff91823125>] mutex_lock_nested+0x65/0x350
[  983.686967]        [<ffffffff9128ec51>] blkdev_put+0x31/0x150
[  983.692761]        [<ffffffffc033481f>] btrfs_close_bdev+0x4f/0x60 [btrfs]
[  983.699699]        [<ffffffffc033d77b>] __btrfs_close_devices+0xcb/0x200 [btrfs]
[  983.707178]        [<ffffffffc033d8db>] btrfs_close_devices+0x2b/0xa0 [btrfs]
[  983.714380]        [<ffffffffc03081c5>] close_ctree+0x265/0x340 [btrfs]
[  983.721061]        [<ffffffffc02d7959>] btrfs_put_super+0x19/0x20 [btrfs]
[  983.727908]        [<ffffffff91250e2f>] generic_shutdown_super+0x6f/0x100
[  983.734744]        [<ffffffff91250f56>] kill_anon_super+0x16/0x30
[  983.740888]        [<ffffffffc02da97e>] btrfs_kill_super+0x1e/0x130 [btrfs]
[  983.747909]        [<ffffffff91250fe9>] deactivate_locked_super+0x49/0x80
[  983.754745]        [<ffffffff912515fd>] deactivate_super+0x5d/0x70
[  983.760977]        [<ffffffff91270a1c>] cleanup_mnt+0x5c/0x80
[  983.766773]        [<ffffffff91270a92>] __cleanup_mnt+0x12/0x20
[  983.772738]        [<ffffffff910aa2fe>] task_work_run+0x7e/0xc0
[  983.778708]        [<ffffffff91081b5a>] exit_to_usermode_loop+0x7e/0xb4
[  983.785373]        [<ffffffff910039eb>] syscall_return_slowpath+0xbb/0xd0
[  983.792212]        [<ffffffff9182605c>] entry_SYSCALL_64_fastpath+0xbf/0xc1
[  983.799225]
[  983.799225] other info that might help us debug this:
[  983.799225]
[  983.807291] Chain exists of:
  &bdev->bd_mutex --> namespace_sem --> &fs_devs->device_list_mutex

[  983.816521]  Possible unsafe locking scenario:
[  983.816521]
[  983.822489]        CPU0                    CPU1
[  983.827043]        ----                    ----
[  983.831599]   lock(&fs_devs->device_list_mutex);
[  983.836289]                                lock(namespace_sem);
[  983.842268]                                lock(&fs_devs->device_list_mutex);
[  983.849478]   lock(&bdev->bd_mutex);
[  983.853127]
[  983.853127]  *** DEADLOCK ***
[  983.853127]
[  983.859113] 3 locks held by umount/21720:
[  983.863145]  #0:  (&type->s_umount_key#35){++++..}, at: [<ffffffff912515f5>] deactivate_super+0x55/0x70
[  983.872713]  #1:  (uuid_mutex){+.+.+.}, at: [<ffffffffc033d8d3>] btrfs_close_devices+0x23/0xa0 [btrfs]
[  983.882206]  #2:  (&fs_devs->device_list_mutex){+.+...}, at: [<ffffffffc033d6f6>] __btrfs_close_devices+0x46/0x200 [btrfs]
[  983.893422]
[  983.893422] stack backtrace:
[  983.897824] CPU: 6 PID: 21720 Comm: umount Not tainted 4.8.0-rc5-ceph-00023-g1b39cec2 #1
[  983.905958] Hardware name: Supermicro SYS-5018R-WR/X10SRW-F, BIOS 1.0c 09/07/2015
[  983.913492]  0000000000000000 ffff8c8a53c17a38 ffffffff91429521 ffffffff9260f4f0
[  983.921018]  ffffffff92642760 ffff8c8a53c17a88 ffffffff911b2b04 0000000000000050
[  983.928542]  ffffffff9237d620 ffff8c8a5294aee0 ffff8c8a5294aeb8 ffff8c8a5294aee0
[  983.936072] Call Trace:
[  983.938545]  [<ffffffff91429521>] dump_stack+0x85/0xc4
[  983.943715]  [<ffffffff911b2b04>] print_circular_bug+0x1fb/0x20c
[  983.949748]  [<ffffffff910def43>] __lock_acquire+0x1003/0x17b0
[  983.955613]  [<ffffffff910dfd0c>] lock_acquire+0x1bc/0x1f0
[  983.961123]  [<ffffffff9128ec51>] ? blkdev_put+0x31/0x150
[  983.966550]  [<ffffffff91823125>] mutex_lock_nested+0x65/0x350
[  983.972407]  [<ffffffff9128ec51>] ? blkdev_put+0x31/0x150
[  983.977832]  [<ffffffff9128ec51>] blkdev_put+0x31/0x150
[  983.983101]  [<ffffffffc033481f>] btrfs_close_bdev+0x4f/0x60 [btrfs]
[  983.989500]  [<ffffffffc033d77b>] __btrfs_close_devices+0xcb/0x200 [btrfs]
[  983.996415]  [<ffffffffc033d8db>] btrfs_close_devices+0x2b/0xa0 [btrfs]
[  984.003068]  [<ffffffffc03081c5>] close_ctree+0x265/0x340 [btrfs]
[  984.009189]  [<ffffffff9126cc5e>] ? evict_inodes+0x15e/0x170
[  984.014881]  [<ffffffffc02d7959>] btrfs_put_super+0x19/0x20 [btrfs]
[  984.021176]  [<ffffffff91250e2f>] generic_shutdown_super+0x6f/0x100
[  984.027476]  [<ffffffff91250f56>] kill_anon_super+0x16/0x30
[  984.033082]  [<ffffffffc02da97e>] btrfs_kill_super+0x1e/0x130 [btrfs]
[  984.039548]  [<ffffffff91250fe9>] deactivate_locked_super+0x49/0x80
[  984.045839]  [<ffffffff912515fd>] deactivate_super+0x5d/0x70
[  984.051525]  [<ffffffff91270a1c>] cleanup_mnt+0x5c/0x80
[  984.056774]  [<ffffffff91270a92>] __cleanup_mnt+0x12/0x20
[  984.062201]  [<ffffffff910aa2fe>] task_work_run+0x7e/0xc0
[  984.067625]  [<ffffffff91081b5a>] exit_to_usermode_loop+0x7e/0xb4
[  984.073747]  [<ffffffff910039eb>] syscall_return_slowpath+0xbb/0xd0
[  984.080038]  [<ffffffff9182605c>] entry_SYSCALL_64_fastpath+0xbf/0xc1

Reported-by: Ilya Dryomov <idryomov@gmail.com>
Signed-off-by: Anand Jain <anand.jain@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2016-09-26 19:37:06 +02:00
..
tests Btrfs: add a flags field to btrfs_fs_info 2016-09-26 17:59:49 +02:00
acl.c btrfs: Replace -ENOENT by -ERANGE in btrfs_get_acl() 2016-07-26 13:52:25 +02:00
async-thread.c btrfs: plumb fs_info into btrfs_work 2016-07-26 13:53:15 +02:00
async-thread.h btrfs: plumb fs_info into btrfs_work 2016-07-26 13:53:15 +02:00
backref.c btrfs: convert pr_* to btrfs_* where possible 2016-09-26 19:37:04 +02:00
backref.h btrfs: cleanup, remove inode_item_info helper 2015-01-14 19:23:47 +01:00
btrfs_inode.h Btrfs: add a flags field to btrfs_fs_info 2016-09-26 17:59:49 +02:00
check-integrity.c btrfs: convert printk(KERN_* to use pr_* calls 2016-09-26 18:08:44 +02:00
check-integrity.h fs: have submit_bh users pass in op and flags separately 2016-06-07 13:41:38 -06:00
compression.c btrfs: convert pr_* to btrfs_* where possible 2016-09-26 19:37:04 +02:00
compression.h btrfs: move btrfs_compression_type to compression.h 2016-03-11 17:12:46 +01:00
ctree.c btrfs: convert printk(KERN_* to use pr_* calls 2016-09-26 18:08:44 +02:00
ctree.h btrfs: btrfs_debug should consume fs_info when DEBUG is not defined 2016-09-26 19:37:06 +02:00
dedupe.h btrfs: expand cow_file_range() to support in-band dedup and subpage-blocksize 2016-07-26 13:52:25 +02:00
delayed-inode.c btrfs: unsplit printed strings 2016-09-26 18:08:44 +02:00
delayed-inode.h Btrfs: fix ->iterate_shared() by upgrading i_rwsem for delayed nodes 2016-06-25 06:20:10 -07:00
delayed-ref.c btrfs: convert pr_* to btrfs_* where possible 2016-09-26 19:37:04 +02:00
delayed-ref.h Btrfs: remove unused function btrfs_add_delayed_qgroup_reserve() 2016-08-03 11:02:51 +01:00
dev-replace.c btrfs: convert pr_* to btrfs_* where possible 2016-09-26 19:37:04 +02:00
dev-replace.h btrfs: refactor btrfs_dev_replace_start for reuse 2016-04-28 10:59:13 +02:00
dir-item.c btrfs: unsplit printed strings 2016-09-26 18:08:44 +02:00
disk-io.c btrfs: convert pr_* to btrfs_* where possible 2016-09-26 19:37:04 +02:00
disk-io.h Btrfs: fix memory leak of block group cache 2016-09-26 17:59:49 +02:00
export.c BTRFS: support NFSv2 export 2015-10-06 06:55:23 -07:00
export.h
extent_io.c btrfs: convert pr_* to btrfs_* where possible 2016-09-26 19:37:04 +02:00
extent_io.h Btrfs: kill the start argument to read_extent_buffer_pages 2016-09-26 17:59:49 +02:00
extent_map.c btrfs: Fix slab accounting flags 2016-07-26 13:52:25 +02:00
extent_map.h btrfs: cleanup, stop casting for extent_map->lookup everywhere 2016-01-15 19:22:28 +01:00
extent-tree.c Btrfs: fix memory leak in do_walk_down 2016-09-26 19:37:06 +02:00
file-item.c Btrfs: fix __MAX_CSUM_ITEMS 2016-08-03 14:08:37 -07:00
file.c Btrfs: kill BUG_ON()'s in btrfs_mark_extent_written 2016-09-26 17:59:49 +02:00
free-space-cache.c btrfs: convert pr_* to btrfs_* where possible 2016-09-26 19:37:04 +02:00
free-space-cache.h btrfs: convert pr_* to btrfs_* where possible 2016-09-26 19:37:04 +02:00
free-space-tree.c btrfs: convert pr_* to btrfs_* where possible 2016-09-26 19:37:04 +02:00
free-space-tree.h Btrfs: implement the free space B-tree 2015-12-17 12:16:47 -08:00
hash.c btrfs: advertise which crc32c implementation is being used at module load 2016-06-06 14:08:28 +02:00
hash.h btrfs: advertise which crc32c implementation is being used at module load 2016-06-06 14:08:28 +02:00
inode-item.c btrfs: rename btrfs_std_error to btrfs_handle_fs_error 2016-04-28 10:36:54 +02:00
inode-map.c btrfs: convert pr_* to btrfs_* where possible 2016-09-26 19:37:04 +02:00
inode-map.h Btrfs: Initialize btrfs_root->highest_objectid when loading tree root and subvolume roots 2016-01-15 19:25:02 +01:00
inode.c btrfs: convert pr_* to btrfs_* where possible 2016-09-26 19:37:04 +02:00
ioctl.c btrfs: unsplit printed strings 2016-09-26 18:08:44 +02:00
Kconfig rcu: Make SRCU optional by using CONFIG_SRCU 2015-01-06 11:04:29 -08:00
locking.c btrfs: cleanup, remove stray return statements 2016-01-07 14:30:52 +01:00
locking.h
lzo.c btrfs: convert printk(KERN_* to use pr_* calls 2016-09-26 18:08:44 +02:00
Makefile Btrfs: add free space tree sanity tests 2015-12-17 12:16:47 -08:00
math.h btrfs: cleanup 64bit/32bit divs, compile time constants 2015-03-03 17:23:57 +01:00
ordered-data.c btrfs: unsplit printed strings 2016-09-26 18:08:44 +02:00
ordered-data.h Btrfs: fix race setting block group readonly during device replace 2016-05-30 12:58:21 +01:00
orphan.c
print-tree.c btrfs: convert printk(KERN_* to use pr_* calls 2016-09-26 18:08:44 +02:00
print-tree.h
props.c btrfs: simpilify btrfs_subvol_inherit_props 2016-07-26 13:54:22 +02:00
props.h
qgroup.c btrfs: convert pr_* to btrfs_* where possible 2016-09-26 19:37:04 +02:00
qgroup.h btrfs: qgroup: Refactor btrfs_qgroup_insert_dirty_extent() 2016-08-25 03:58:21 -07:00
raid56.c Btrfs: remove BUG() in raid56 2016-09-26 17:59:49 +02:00
raid56.h Btrfs: add RAID 5/6 BTRFS_RBIO_REBUILD_MISSING operation 2015-08-09 07:34:26 -07:00
rcu-string.h
reada.c btrfs: convert pr_* to btrfs_* where possible 2016-09-26 19:37:04 +02:00
relocation.c btrfs: unsplit printed strings 2016-09-26 18:08:44 +02:00
root-tree.c btrfs: unsplit printed strings 2016-09-26 18:08:44 +02:00
scrub.c btrfs: unsplit printed strings 2016-09-26 18:08:44 +02:00
send.c btrfs: convert send's verbose_printk to btrfs_debug 2016-09-26 19:37:06 +02:00
send.h Btrfs: use linux/sizes.h to represent constants 2016-01-07 14:38:02 +01:00
struct-funcs.c btrfs: fix string and comment grammatical issues and typos 2016-05-25 22:35:14 +02:00
super.c btrfs: convert pr_* to btrfs_* where possible 2016-09-26 19:37:04 +02:00
sysfs.c btrfs: convert printk(KERN_* to use pr_* calls 2016-09-26 18:08:44 +02:00
sysfs.h btrfs: sysfs: introduce helper for syncing bits with sysfs files 2016-01-21 18:50:40 +01:00
transaction.c btrfs: convert pr_* to btrfs_* where possible 2016-09-26 19:37:04 +02:00
transaction.h btrfs: convert pr_* to btrfs_* where possible 2016-09-26 19:37:04 +02:00
tree-defrag.c Btrfs: fix locking bugs when defragging leaves 2015-12-18 02:51:32 +00:00
tree-log.c btrfs: unsplit printed strings 2016-09-26 18:08:44 +02:00
tree-log.h Btrfs: fix lockdep warning on deadlock against an inode's log mutex 2016-08-25 03:58:32 -07:00
ulist.c btrfs: fix string and comment grammatical issues and typos 2016-05-25 22:35:14 +02:00
ulist.h btrfs: ulist: Add ulist_del() function. 2015-06-10 09:26:17 -07:00
uuid-tree.c btrfs: unsplit printed strings 2016-09-26 18:08:44 +02:00
volumes.c btrfs: fix a possible umount deadlock 2016-09-26 19:37:06 +02:00
volumes.h btrfs: convert pr_* to btrfs_* where possible 2016-09-26 19:37:04 +02:00
xattr.c switch xattr_handler->set() to passing dentry and inode separately 2016-05-27 15:39:43 -04:00
xattr.h btrfs: Switch to generic xattr handlers 2016-05-17 19:17:09 -04:00
zlib.c btrfs: convert printk(KERN_* to use pr_* calls 2016-09-26 18:08:44 +02:00