linux/fs
Boris Burkov 12148367d7 btrfs: fix potential dead lock in size class loading logic
As reported by Filipe, there's a potential deadlock caused by
using btrfs_search_forward on commit_root. The locking there is
unconditional, even if ->skip_locking and ->search_commit_root is set.
It's not meant to be used for commit roots, so it always needs to do
locking.

So if another task is COWing a child node of the same root node and
then needs to wait for block group caching to complete when trying to
allocate a metadata extent, it deadlocks.

For example:

[539604.239315] sysrq: Show Blocked State
[539604.240133] task:kworker/u16:6   state:D stack:0     pid:2119594 ppid:2      flags:0x00004000
[539604.241613] Workqueue: btrfs-cache btrfs_work_helper [btrfs]
[539604.242673] Call Trace:
[539604.243129]  <TASK>
[539604.243925]  __schedule+0x41d/0xee0
[539604.244797]  ? rcu_read_lock_sched_held+0x12/0x70
[539604.245399]  ? rwsem_down_read_slowpath+0x185/0x490
[539604.246111]  schedule+0x5d/0xf0
[539604.246593]  rwsem_down_read_slowpath+0x2da/0x490
[539604.247290]  ? rcu_barrier_tasks_trace+0x10/0x20
[539604.248090]  __down_read_common+0x3d/0x150
[539604.248702]  down_read_nested+0xc3/0x140
[539604.249280]  __btrfs_tree_read_lock+0x24/0x100 [btrfs]
[539604.250097]  btrfs_read_lock_root_node+0x48/0x60 [btrfs]
[539604.250915]  btrfs_search_forward+0x59/0x460 [btrfs]
[539604.251781]  ? btrfs_global_root+0x50/0x70 [btrfs]
[539604.252476]  caching_thread+0x1be/0x920 [btrfs]
[539604.253167]  btrfs_work_helper+0xf6/0x400 [btrfs]
[539604.253848]  process_one_work+0x24f/0x5a0
[539604.254476]  worker_thread+0x52/0x3b0
[539604.255166]  ? __pfx_worker_thread+0x10/0x10
[539604.256047]  kthread+0xf0/0x120
[539604.256591]  ? __pfx_kthread+0x10/0x10
[539604.257212]  ret_from_fork+0x29/0x50
[539604.257822]  </TASK>
[539604.258233] task:btrfs-transacti state:D stack:0     pid:2236474 ppid:2      flags:0x00004000
[539604.259802] Call Trace:
[539604.260243]  <TASK>
[539604.260615]  __schedule+0x41d/0xee0
[539604.261205]  ? rcu_read_lock_sched_held+0x12/0x70
[539604.262000]  ? rwsem_down_read_slowpath+0x185/0x490
[539604.262822]  schedule+0x5d/0xf0
[539604.263374]  rwsem_down_read_slowpath+0x2da/0x490
[539604.266228]  ? lock_acquire+0x160/0x310
[539604.266917]  ? rcu_read_lock_sched_held+0x12/0x70
[539604.267996]  ? lock_contended+0x19e/0x500
[539604.268720]  __down_read_common+0x3d/0x150
[539604.269400]  down_read_nested+0xc3/0x140
[539604.270057]  __btrfs_tree_read_lock+0x24/0x100 [btrfs]
[539604.271129]  btrfs_read_lock_root_node+0x48/0x60 [btrfs]
[539604.272372]  btrfs_search_slot+0x143/0xf70 [btrfs]
[539604.273295]  update_block_group_item+0x9e/0x190 [btrfs]
[539604.274282]  btrfs_start_dirty_block_groups+0x1c4/0x4f0 [btrfs]
[539604.275381]  ? __mutex_unlock_slowpath+0x45/0x280
[539604.276390]  btrfs_commit_transaction+0xee/0xed0 [btrfs]
[539604.277391]  ? lock_acquire+0x1a4/0x310
[539604.278080]  ? start_transaction+0xcb/0x6c0 [btrfs]
[539604.279099]  transaction_kthread+0x142/0x1c0 [btrfs]
[539604.279996]  ? __pfx_transaction_kthread+0x10/0x10 [btrfs]
[539604.280673]  kthread+0xf0/0x120
[539604.281050]  ? __pfx_kthread+0x10/0x10
[539604.281496]  ret_from_fork+0x29/0x50
[539604.281966]  </TASK>
[539604.282255] task:fsstress        state:D stack:0     pid:2236483 ppid:1      flags:0x00004006
[539604.283897] Call Trace:
[539604.284700]  <TASK>
[539604.285088]  __schedule+0x41d/0xee0
[539604.285660]  schedule+0x5d/0xf0
[539604.286175]  btrfs_wait_block_group_cache_progress+0xf2/0x170 [btrfs]
[539604.287342]  ? __pfx_autoremove_wake_function+0x10/0x10
[539604.288450]  find_free_extent+0xd93/0x1750 [btrfs]
[539604.289256]  ? _raw_spin_unlock+0x29/0x50
[539604.289911]  ? btrfs_get_alloc_profile+0x127/0x2a0 [btrfs]
[539604.290843]  btrfs_reserve_extent+0x147/0x290 [btrfs]
[539604.291943]  btrfs_alloc_tree_block+0xcb/0x3e0 [btrfs]
[539604.292903]  __btrfs_cow_block+0x138/0x580 [btrfs]
[539604.293773]  btrfs_cow_block+0x10e/0x240 [btrfs]
[539604.294595]  btrfs_search_slot+0x7f3/0xf70 [btrfs]
[539604.295585]  btrfs_update_device+0x71/0x1b0 [btrfs]
[539604.296459]  btrfs_chunk_alloc_add_chunk_item+0xe0/0x340 [btrfs]
[539604.297489]  btrfs_chunk_alloc+0x1bf/0x490 [btrfs]
[539604.298335]  find_free_extent+0x6fa/0x1750 [btrfs]
[539604.299174]  ? _raw_spin_unlock+0x29/0x50
[539604.299950]  ? btrfs_get_alloc_profile+0x127/0x2a0 [btrfs]
[539604.300918]  btrfs_reserve_extent+0x147/0x290 [btrfs]
[539604.301797]  btrfs_alloc_tree_block+0xcb/0x3e0 [btrfs]
[539604.303017]  ? lock_release+0x224/0x4a0
[539604.303855]  __btrfs_cow_block+0x138/0x580 [btrfs]
[539604.304789]  btrfs_cow_block+0x10e/0x240 [btrfs]
[539604.305611]  btrfs_search_slot+0x7f3/0xf70 [btrfs]
[539604.306682]  ? btrfs_global_root+0x50/0x70 [btrfs]
[539604.308198]  lookup_inline_extent_backref+0x17b/0x7a0 [btrfs]
[539604.309254]  lookup_extent_backref+0x43/0xd0 [btrfs]
[539604.310122]  __btrfs_free_extent+0xf8/0x810 [btrfs]
[539604.310874]  ? lock_release+0x224/0x4a0
[539604.311724]  ? btrfs_merge_delayed_refs+0x17b/0x1d0 [btrfs]
[539604.313023]  __btrfs_run_delayed_refs+0x2ba/0x1260 [btrfs]
[539604.314271]  btrfs_run_delayed_refs+0x8f/0x1c0 [btrfs]
[539604.315445]  ? rcu_read_lock_sched_held+0x12/0x70
[539604.316706]  btrfs_commit_transaction+0xa2/0xed0 [btrfs]
[539604.317855]  ? do_raw_spin_unlock+0x4b/0xa0
[539604.318544]  ? _raw_spin_unlock+0x29/0x50
[539604.319240]  create_subvol+0x53d/0x6e0 [btrfs]
[539604.320283]  btrfs_mksubvol+0x4f5/0x590 [btrfs]
[539604.321220]  __btrfs_ioctl_snap_create+0x11b/0x180 [btrfs]
[539604.322307]  btrfs_ioctl_snap_create_v2+0xc6/0x150 [btrfs]
[539604.323295]  btrfs_ioctl+0x9f7/0x33e0 [btrfs]
[539604.324331]  ? rcu_read_lock_sched_held+0x12/0x70
[539604.325137]  ? lock_release+0x224/0x4a0
[539604.325808]  ? __x64_sys_ioctl+0x87/0xc0
[539604.326467]  __x64_sys_ioctl+0x87/0xc0
[539604.327109]  do_syscall_64+0x38/0x90
[539604.327875]  entry_SYSCALL_64_after_hwframe+0x72/0xdc
[539604.328792] RIP: 0033:0x7f05a7babaeb

This needs to use regular btrfs_search_slot() with some skip and stop
logic.

Since we only consider five samples (five search slots), don't bother
with the complexity of looking for commit_root_sem contention. If
necessary, it can be added to the load function in between samples.

Reported-by: Filipe Manana <fdmanana@kernel.org>
Link: https://lore.kernel.org/linux-btrfs/CAL3q7H7eKMD44Z1+=Kb-1RFMMeZpAm2fwyO59yeBwCcSOU80Pg@mail.gmail.com/
Fixes: c7eec3d9aa ("btrfs: load block group size class when caching")
Signed-off-by: Boris Burkov <boris@bur.io>
Signed-off-by: David Sterba <dsterba@suse.com>
2023-03-06 19:28:19 +01:00
..
9p 9p-for-6.2-rc1 2022-12-23 11:39:18 -08:00
adfs fs: Convert block_read_full_page() to block_read_full_folio() 2022-05-09 16:21:44 -04:00
affs affs: initialize fsdata in affs_truncate() 2023-01-10 14:55:20 +01:00
afs rxrpc: Move call state changes from recvmsg to I/O thread 2023-01-06 09:43:33 +00:00
autofs autofs: remove unused ino field inode 2022-07-17 17:31:42 -07:00
befs befs: Convert befs_symlink_read_folio() to use a folio 2022-08-02 12:34:03 -04:00
bfs fs: Convert block_read_full_page() to block_read_full_folio() 2022-05-09 16:21:44 -04:00
btrfs btrfs: fix potential dead lock in size class loading logic 2023-03-06 19:28:19 +01:00
cachefiles fscache,cachefiles: add prepare_ondemand_read() callback 2022-12-07 10:56:29 +08:00
ceph ceph: flush cap releases when the session is flushed 2023-02-07 16:55:14 +01:00
cifs cifs: Fix use-after-free in rdata->read_into_pages() 2023-02-06 22:50:25 -06:00
coda coda: Convert coda_symlink_filler() to use a folio 2022-08-02 12:34:03 -04:00
configfs configfs: fix possible memory leak in configfs_create_dir() 2022-12-02 11:11:22 +01:00
cramfs cramfs: read_mapping_page() is synchronous 2022-08-02 12:34:02 -04:00
crypto for-6.2/block-2022-12-08 2022-12-13 10:43:59 -08:00
debugfs debugfs: fix error when writing negative value to atomic_t debugfs file 2022-11-30 16:13:16 -08:00
devpts
dlm Treewide: Stop corrupting socket's task_frag 2022-12-19 17:28:49 -08:00
ecryptfs ecryptfs: use stub posix acl handlers 2022-10-20 10:13:31 +02:00
efivarfs efi: vars: prohibit reading random seed variables 2022-12-01 09:51:21 +01:00
efs efs: Convert efs symlinks to read_folio 2022-05-09 16:21:45 -04:00
erofs erofs: clean up parsing of fscache related options 2023-01-16 22:39:47 +08:00
exfat Description for this pull request: 2022-12-15 18:14:21 -08:00
exportfs exportfs: use pr_debug for unreachable debug statements 2022-11-28 12:54:45 -05:00
ext2 \n 2022-12-12 20:32:50 -08:00
ext4 ext4: make xattr char unsignedness in hash explicit 2023-01-24 12:38:45 -08:00
f2fs f2fs: let's avoid panic if extent_tree is not created 2023-01-03 08:59:06 -08:00
fat MM patches for 6.2-rc1. 2022-12-13 19:29:45 -08:00
freevxfs freevxfs: Kconfig: fix spelling 2023-01-31 16:44:08 -08:00
fscache fscache: Use clear_and_wake_up_bit() in fscache_create_volume_work() 2023-01-30 12:51:54 +00:00
fuse fuse: fixes after adapting to new posix acl api 2023-01-24 16:33:37 +01:00
gfs2 Revert "gfs2: stop using generic_writepages in gfs2_ail1_start_one" 2023-01-22 09:46:14 +01:00
hfs hfs/hfsplus: avoid WARN_ON() for sanity check, use proper error handling 2023-01-06 14:09:13 -08:00
hfsplus MM patches for 6.2-rc1. 2022-12-13 19:29:45 -08:00
hostfs hostfs: move from strlcpy with unused retval to strscpy 2022-09-19 22:46:25 +02:00
hpfs hpfs: remove ->writepage 2022-12-11 18:12:18 -08:00
hugetlbfs hugetlbfs: inode: remove unnecessary (void*) conversions 2022-11-30 15:58:56 -08:00
iomap iomap: remove IOMAP_F_ZONE_APPEND 2023-02-15 19:38:53 +01:00
isofs - hfs and hfsplus kmap API modernization from Fabio Francesco 2022-10-12 11:00:22 -07:00
jbd2 jbd2: switch jbd2_submit_inode_data() to use fs-provided hook for data writeout 2022-12-08 21:49:25 -05:00
jffs2 fs: rename current get acl method 2022-10-20 10:13:27 +02:00
jfs MM patches for 6.2-rc1. 2022-12-13 19:29:45 -08:00
kernfs kernfs: fix all kernel-doc warnings and multiple typos 2022-11-23 19:28:26 +01:00
ksmbd ksmbd: downgrade ndr version error message to debug 2023-01-25 18:31:18 -06:00
lockd NFSD 6.2 Release Notes 2022-12-12 20:54:39 -08:00
minix vfs: open inside ->tmpfile() 2022-09-24 07:00:00 +02:00
netfs use less confusing names for iov_iter direction initializers 2022-11-25 13:01:55 -05:00
nfs NFS client fixes for Linux 6.2 2023-01-07 10:38:11 -08:00
nfs_common
nfsd nfsd-6.2 fixes: 2023-01-24 12:58:47 -08:00
nilfs2 nilfs2: fix general protection fault in nilfs_btree_insert() 2023-01-11 16:14:21 -08:00
nls
notify Merge tag 'fsnotify-for_v6.1-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs 2022-10-07 08:28:50 -07:00
ntfs - hfs and hfsplus kmap API modernization from Fabio Francesco 2022-10-12 11:00:22 -07:00
ntfs3 fs/ntfs3: don't hold ni_lock when calling truncate_setsize() 2023-01-02 10:31:09 -08:00
ocfs2 Treewide: Stop corrupting socket's task_frag 2022-12-19 17:28:49 -08:00
omfs omfs: remove ->writepage 2022-12-11 18:12:18 -08:00
openpromfs fs: allocate inode by using alloc_inode_sb() 2022-03-22 15:57:03 -07:00
orangefs orangefs: four fixes from Zhang Xiaoxu and two from Colin Ian King 2022-12-14 11:16:33 -08:00
overlayfs ovl: fail on invalid uid/gid mapping at copy up 2023-01-27 16:17:19 +01:00
proc mm: hugetlb: proc: check for hugetlb shared PMD in /proc/PID/smaps 2023-01-31 16:44:09 -08:00
pstore pstore updates for v6.2-rc1-fixes 2022-12-23 11:55:54 -08:00
qnx4 fs: Convert block_read_full_page() to block_read_full_folio() 2022-05-09 16:21:44 -04:00
qnx6 fs/qnx6: delete unnecessary checks before brelse() 2022-09-11 21:55:07 -07:00
quota ext4: fix bug_on in __es_tree_search caused by bad quota inode 2022-12-08 21:49:23 -05:00
ramfs tmpfile API change 2022-10-10 19:45:17 -07:00
reiserfs lsm/stable-6.2 PR 20221212 2022-12-13 09:47:48 -08:00
romfs romfs: Convert romfs to read_folio 2022-05-09 16:21:46 -04:00
smbfs_common smb3: define missing create contexts 2022-10-05 01:55:27 -05:00
squashfs Squashfs: fix handling and sanity checking of xattr_ids count 2023-01-31 16:44:10 -08:00
sysfs kobject: kobj_type: remove default_attrs 2022-04-05 15:39:19 +02:00
sysv fs: sysv: Fix sysv_nblocks() returns wrong value 2022-12-10 14:13:37 -05:00
tracefs tracefs: Only clobber mode/uid/gid on remount if asked 2022-09-08 17:10:54 -04:00
ubifs treewide: use get_random_u32_below() instead of deprecated function 2022-11-18 02:15:15 +01:00
udf udf: initialize newblock to 0 2023-01-06 15:44:32 +01:00
ufs ufs: replace ll_rw_block() 2022-09-11 20:26:07 -07:00
unicode
vboxsf vboxsf: Convert vboxsf to read_folio 2022-05-09 16:21:46 -04:00
verity fsverity: simplify fsverity_get_digest() 2022-11-29 21:07:41 -08:00
xfs xfs: fix extent busy updating 2023-01-05 07:34:21 -08:00
zonefs zonefs: Detect append writes at invalid locations 2023-01-16 08:42:12 +09:00
aio.c use less confusing names for iov_iter direction initializers 2022-11-25 13:01:55 -05:00
anon_inodes.c dynamic_dname(): drop unused dentry argument 2022-08-20 11:34:04 -04:00
attr.c attr: use consistent sgid stripping checks 2022-10-18 10:09:47 +02:00
bad_inode.c fs: rename current get acl method 2022-10-20 10:13:27 +02:00
binfmt_elf_fdpic.c elfcore: Add a cprm parameter to elf_core_extra_{phdrs,data_size} 2023-01-05 15:12:12 +00:00
binfmt_elf_test.c
binfmt_elf.c elfcore: Add a cprm parameter to elf_core_extra_{phdrs,data_size} 2023-01-05 15:12:12 +00:00
binfmt_flat.c binfmt_flat: Remove shared library support 2022-04-22 10:57:18 -07:00
binfmt_misc.c binfmt_misc: fix shift-out-of-bounds in check_special_flags 2022-12-02 13:57:04 -08:00
binfmt_script.c
buffer.c - hfs and hfsplus kmap API modernization from Fabio Francesco 2022-10-12 11:00:22 -07:00
char_dev.c chardev: fix error handling in cdev_device_add() 2022-12-02 17:48:59 +01:00
compat_binfmt_elf.c
coredump.c coredump: Move dump_emit_page() to kill unused warning 2023-01-10 21:03:01 -05:00
d_path.c d_path.c: typo fix... 2022-08-20 11:34:33 -04:00
dax.c fsdax,xfs: port unshare to fsdax 2022-12-11 18:12:17 -08:00
dcache.c tmpfile API change 2022-10-10 19:45:17 -07:00
direct-io.c block: remove PSI accounting from the bio layer 2022-09-20 08:24:38 -06:00
drop_caches.c
eventfd.c eventfd: provide a eventfd_signal_mask() helper 2022-11-22 06:07:55 -07:00
eventpoll.c eventpoll: add EPOLL_URING_WAKE poll wakeup flag 2022-11-21 07:45:29 -07:00
exec.c fs.vfsuid.conversion.v6.2 2022-12-12 19:20:05 -08:00
fcntl.c keep iocb_flags() result cached in struct file 2022-06-10 16:10:23 -04:00
fhandle.c do_sys_name_to_handle(): constify path 2022-09-01 17:36:39 -04:00
file_table.c locks: fix TOCTOU race when granting write lease 2022-08-16 10:59:54 -04:00
file.c fs: use acquire ordering in __fget_light() 2022-10-31 15:30:11 -04:00
filesystems.c
fs_context.c
fs_parser.c ext4: journal_path mount options should follow links 2022-12-01 10:46:54 -05:00
fs_pin.c
fs_struct.c
fs_types.c
fs-writeback.c for-6.2/writeback-2022-12-12 2022-12-15 18:09:48 -08:00
fsopen.c uninline may_mount() and don't opencode it in fspick(2)/fsopen(2) 2022-05-19 23:25:10 -04:00
init.c
inode.c fs.vfsuid.conversion.v6.2 2022-12-12 19:20:05 -08:00
internal.h fs.ovl.setgid.v6.2 2022-12-12 19:03:10 -08:00
ioctl.c Fixes for 5.18-rc1: 2022-04-01 19:35:56 -07:00
Kconfig hugetlb: make hugetlb depends on SYSFS or SYSCTL 2022-09-11 20:26:10 -07:00
Kconfig.binfmt Xtensa updates for v6.1 2022-10-10 14:21:11 -07:00
kernel_read_file.c fs/kernel_read_file: allow to read files up-to ssize_t 2022-06-16 19:58:21 -07:00
libfs.c libfs: add DEFINE_SIMPLE_ATTRIBUTE_SIGNED for signed value 2022-11-30 16:13:16 -08:00
locks.c Add process name and pid to locks warning 2022-11-30 05:08:10 -05:00
Makefile a.out: Remove the a.out implementation 2022-09-27 07:11:02 -07:00
mbcache.c ext4: fix deadlock due to mbcache entry corruption 2022-12-08 21:49:25 -05:00
mount.h switch try_to_unlazy_next() to __legitimize_mnt() 2022-07-05 16:18:21 -04:00
mpage.c Folio changes for 6.0 2022-08-03 10:35:43 -07:00
namei.c Landlock updates for v6.2-rc1 2022-12-13 09:14:50 -08:00
namespace.c fs.idmapped.mnt_idmap.v6.2 2022-12-12 19:30:18 -08:00
no-block.c
nsfs.c dynamic_dname(): drop unused dentry argument 2022-08-20 11:34:04 -04:00
open.c Landlock updates for v6.2-rc1 2022-12-13 09:14:50 -08:00
pipe.c dynamic_dname(): drop unused dentry argument 2022-08-20 11:34:04 -04:00
pnode.c pnode: terminate at peers of source 2022-12-21 14:45:25 +01:00
pnode.h
posix_acl.c fs.idmapped.mnt_idmap.v6.2 2022-12-12 19:30:18 -08:00
proc_namespace.c vfs: escape hash as well 2022-06-28 13:58:05 -04:00
read_write.c iov_iter work; most of that is about getting rid of 2022-12-12 18:29:54 -08:00
readdir.c Change calling conventions for filldir_t 2022-08-17 17:25:04 -04:00
remap_range.c New VFS code for 6.2: 2022-12-13 10:26:38 -08:00
select.c
seq_file.c use less confusing names for iov_iter direction initializers 2022-11-25 13:01:55 -05:00
signalfd.c
splice.c use less confusing names for iov_iter direction initializers 2022-11-25 13:01:55 -05:00
stack.c
stat.c fs: use type safe idmapping helpers 2022-10-26 10:02:34 +02:00
statfs.c
super.c misc pile 2022-12-12 18:38:47 -08:00
sync.c riscv: compat: syscall: Add compat_sys_call_table implementation 2022-04-26 13:36:25 -07:00
sysctls.c
timerfd.c
userfaultfd.c mm/userfaultfd: enable writenotify while userfaultfd-wp is enabled for a VMA 2023-01-11 16:14:20 -08:00
utimes.c
xattr.c fs.xattr.simple.rework.rbtree.rwlock.v6.2 2022-12-13 10:08:36 -08:00