syzbot


possible deadlock in dqget (2)

Status: upstream: reported on 2026/01/24 00:53
Subsystems: ocfs2
[Documentation on labels]
Reported-by: syzbot+e7e874621d086b64b4ca@syzkaller.appspotmail.com
First crash: 58d, last: 5d06h
Discussions (1)
Title Replies (including bot) Last reply
[syzbot] [fs?] possible deadlock in dqget (2) 1 (2) 2026/02/01 04:21
Similar bugs (5)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-6.6 possible deadlock in dqget 4 28 9d06h 272d 0/2 upstream: reported on 2025/06/20 12:37
linux-6.1 possible deadlock in dqget 4 1 415d 415d 0/3 auto-obsoleted due to no activity on 2025/05/07 22:20
upstream possible deadlock in dqget ocfs2 ext4 4 C error 100357 80d 534d 29/29 fixed on 2026/01/07 12:29
linux-5.15 possible deadlock in dqget 4 1 54d 54d 0/3 upstream: reported on 2026/01/23 21:59
linux-6.1 possible deadlock in dqget (2) 4 11 147d 261d 0/3 auto-obsoleted due to no activity on 2026/01/30 18:00

Sample crash report:
ocfs2: Mounting device (7,4) on (node local, slot 0) with ordered data mode.
======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.4.719/10360 is trying to acquire lock:
ffff888068b0aea8 (&dquot->dq_lock){+.+.}-{4:4}, at: wait_on_dquot fs/quota/dquot.c:357 [inline]
ffff888068b0aea8 (&dquot->dq_lock){+.+.}-{4:4}, at: dqget+0x72a/0xf10 fs/quota/dquot.c:975

but task is already holding lock:
ffff8880534742c0 (&ocfs2_sysfile_lock_key[INODE_ALLOC_SYSTEM_INODE]){+.+.}-{4:4}, at: inode_lock include/linux/fs.h:1028 [inline]
ffff8880534742c0 (&ocfs2_sysfile_lock_key[INODE_ALLOC_SYSTEM_INODE]){+.+.}-{4:4}, at: ocfs2_reserve_suballoc_bits+0x16a/0x4940 fs/ocfs2/suballoc.c:857

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #3 (&ocfs2_sysfile_lock_key[INODE_ALLOC_SYSTEM_INODE]){+.+.}-{4:4}:
       down_write+0x96/0x200 kernel/locking/rwsem.c:1590
       inode_lock include/linux/fs.h:1028 [inline]
       ocfs2_remove_inode fs/ocfs2/inode.c:733 [inline]
       ocfs2_wipe_inode fs/ocfs2/inode.c:896 [inline]
       ocfs2_delete_inode fs/ocfs2/inode.c:1157 [inline]
       ocfs2_evict_inode+0x1539/0x44e0 fs/ocfs2/inode.c:1299
       evict+0x61e/0xb10 fs/inode.c:846
       ocfs2_dentry_iput+0x24d/0x390 fs/ocfs2/dcache.c:407
       __dentry_kill+0x1a2/0x5e0 fs/dcache.c:670
       finish_dput+0xc9/0x480 fs/dcache.c:879
       __fput+0x691/0xa70 fs/file_table.c:477
       task_work_run+0x1d9/0x270 kernel/task_work.c:233
       resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
       __exit_to_user_mode_loop kernel/entry/common.c:67 [inline]
       exit_to_user_mode_loop+0xed/0x480 kernel/entry/common.c:98
       __exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline]
       syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:256 [inline]
       syscall_exit_to_user_mode include/linux/entry-common.h:325 [inline]
       do_syscall_64+0x32d/0xf80 arch/x86/entry/syscall_64.c:100
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #2 (&ocfs2_sysfile_lock_key[ORPHAN_DIR_SYSTEM_INODE]){+.+.}-{4:4}:
       down_write+0x96/0x200 kernel/locking/rwsem.c:1590
       inode_lock include/linux/fs.h:1028 [inline]
       ocfs2_del_inode_from_orphan+0x12e/0x7a0 fs/ocfs2/namei.c:2731
       ocfs2_dio_end_io_write fs/ocfs2/aops.c:2305 [inline]
       ocfs2_dio_end_io+0x543/0x1210 fs/ocfs2/aops.c:2403
       dio_complete+0x25b/0x790 fs/direct-io.c:281
       __blockdev_direct_IO+0x2cb0/0x32f0 fs/direct-io.c:1303
       ocfs2_direct_IO+0x251/0x2c0 fs/ocfs2/aops.c:2440
       generic_file_direct_write+0x1db/0x3e0 mm/filemap.c:4253
       __generic_file_write_iter+0x11d/0x230 mm/filemap.c:4422
       ocfs2_file_write_iter+0x1663/0x1ed0 fs/ocfs2/file.c:2476
       iter_file_splice_write+0x9a1/0x10f0 fs/splice.c:736
       do_splice_from fs/splice.c:936 [inline]
       direct_splice_actor+0x101/0x160 fs/splice.c:1159
       splice_direct_to_actor+0x53a/0xc70 fs/splice.c:1103
       do_splice_direct_actor fs/splice.c:1202 [inline]
       do_splice_direct+0x195/0x290 fs/splice.c:1228
       do_sendfile+0x535/0x7d0 fs/read_write.c:1372
       __do_sys_sendfile64 fs/read_write.c:1433 [inline]
       __se_sys_sendfile64+0x144/0x1a0 fs/read_write.c:1419
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #1 (&ocfs2_quota_ip_alloc_sem_key){++++}-{4:4}:
       down_write+0x96/0x200 kernel/locking/rwsem.c:1590
       ocfs2_create_local_dquot+0x1a5/0x1af0 fs/ocfs2/quota_local.c:1227
       ocfs2_acquire_dquot+0x816/0xb70 fs/ocfs2/quota_global.c:883
       dqget+0x7b1/0xf10 fs/quota/dquot.c:980
       dquot_get_next_dqblk+0xb2/0x150 fs/quota/dquot.c:2708
       quota_getnextquota+0x2dc/0x4e0 fs/quota/quota.c:250
       __do_sys_quotactl fs/quota/quota.c:961 [inline]
       __se_sys_quotactl+0x2cd/0x9e0 fs/quota/quota.c:917
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #0 (&dquot->dq_lock){+.+.}-{4:4}:
       check_prev_add kernel/locking/lockdep.c:3165 [inline]
       check_prevs_add kernel/locking/lockdep.c:3284 [inline]
       validate_chain kernel/locking/lockdep.c:3908 [inline]
       __lock_acquire+0x15a5/0x2cf0 kernel/locking/lockdep.c:5237
       lock_acquire+0xf0/0x2e0 kernel/locking/lockdep.c:5868
       __mutex_lock_common kernel/locking/mutex.c:614 [inline]
       __mutex_lock+0x19f/0x1300 kernel/locking/mutex.c:776
       wait_on_dquot fs/quota/dquot.c:357 [inline]
       dqget+0x72a/0xf10 fs/quota/dquot.c:975
       __dquot_initialize+0x3ba/0xd30 fs/quota/dquot.c:1508
       ocfs2_get_init_inode+0x147/0x1c0 fs/ocfs2/namei.c:206
       ocfs2_mknod+0xa67/0x2290 fs/ocfs2/namei.c:314
       ocfs2_create+0x195/0x490 fs/ocfs2/namei.c:677
       lookup_open fs/namei.c:4483 [inline]
       open_last_lookups fs/namei.c:4583 [inline]
       path_openat+0x1395/0x3860 fs/namei.c:4827
       do_file_open+0x23e/0x4a0 fs/namei.c:4859
       do_sys_openat2+0x113/0x200 fs/open.c:1366
       do_sys_open fs/open.c:1372 [inline]
       __do_sys_openat fs/open.c:1388 [inline]
       __se_sys_openat fs/open.c:1383 [inline]
       __x64_sys_openat+0x138/0x170 fs/open.c:1383
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

other info that might help us debug this:

Chain exists of:
  &dquot->dq_lock --> &ocfs2_sysfile_lock_key[ORPHAN_DIR_SYSTEM_INODE] --> &ocfs2_sysfile_lock_key[INODE_ALLOC_SYSTEM_INODE]

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&ocfs2_sysfile_lock_key[INODE_ALLOC_SYSTEM_INODE]);
                               lock(&ocfs2_sysfile_lock_key[ORPHAN_DIR_SYSTEM_INODE]);
                               lock(&ocfs2_sysfile_lock_key[INODE_ALLOC_SYSTEM_INODE]);
  lock(&dquot->dq_lock);

 *** DEADLOCK ***

3 locks held by syz.4.719/10360:
 #0: ffff888061438420 (sb_writers#16){.+.+}-{0:0}, at: mnt_want_write+0x41/0x90 fs/namespace.c:493
 #1: ffff88806893df40 (&type->i_mutex_dir_key#10){++++}-{4:4}, at: inode_lock include/linux/fs.h:1028 [inline]
 #1: ffff88806893df40 (&type->i_mutex_dir_key#10){++++}-{4:4}, at: open_last_lookups fs/namei.c:4580 [inline]
 #1: ffff88806893df40 (&type->i_mutex_dir_key#10){++++}-{4:4}, at: path_openat+0xb4c/0x3860 fs/namei.c:4827
 #2: ffff8880534742c0 (&ocfs2_sysfile_lock_key[INODE_ALLOC_SYSTEM_INODE]){+.+.}-{4:4}, at: inode_lock include/linux/fs.h:1028 [inline]
 #2: ffff8880534742c0 (&ocfs2_sysfile_lock_key[INODE_ALLOC_SYSTEM_INODE]){+.+.}-{4:4}, at: ocfs2_reserve_suballoc_bits+0x16a/0x4940 fs/ocfs2/suballoc.c:857

stack backtrace:
CPU: 0 UID: 0 PID: 10360 Comm: syz.4.719 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 print_circular_bug+0x2e1/0x300 kernel/locking/lockdep.c:2043
 check_noncircular+0x12e/0x150 kernel/locking/lockdep.c:2175
 check_prev_add kernel/locking/lockdep.c:3165 [inline]
 check_prevs_add kernel/locking/lockdep.c:3284 [inline]
 validate_chain kernel/locking/lockdep.c:3908 [inline]
 __lock_acquire+0x15a5/0x2cf0 kernel/locking/lockdep.c:5237
 lock_acquire+0xf0/0x2e0 kernel/locking/lockdep.c:5868
 __mutex_lock_common kernel/locking/mutex.c:614 [inline]
 __mutex_lock+0x19f/0x1300 kernel/locking/mutex.c:776
 wait_on_dquot fs/quota/dquot.c:357 [inline]
 dqget+0x72a/0xf10 fs/quota/dquot.c:975
 __dquot_initialize+0x3ba/0xd30 fs/quota/dquot.c:1508
 ocfs2_get_init_inode+0x147/0x1c0 fs/ocfs2/namei.c:206
 ocfs2_mknod+0xa67/0x2290 fs/ocfs2/namei.c:314
 ocfs2_create+0x195/0x490 fs/ocfs2/namei.c:677
 lookup_open fs/namei.c:4483 [inline]
 open_last_lookups fs/namei.c:4583 [inline]
 path_openat+0x1395/0x3860 fs/namei.c:4827
 do_file_open+0x23e/0x4a0 fs/namei.c:4859
 do_sys_openat2+0x113/0x200 fs/open.c:1366
 do_sys_open fs/open.c:1372 [inline]
 __do_sys_openat fs/open.c:1388 [inline]
 __se_sys_openat fs/open.c:1383 [inline]
 __x64_sys_openat+0x138/0x170 fs/open.c:1383
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7ff61fb9c799
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ff620a0d028 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007ff61fe15fa0 RCX: 00007ff61fb9c799
RDX: 0000000000042842 RSI: 0000200000000040 RDI: ffffffffffffff9c
RBP: 00007ff61fc32c99 R08: 0000000000000000 R09: 0000000000000000
R10: 000000000000008d R11: 0000000000000246 R12: 0000000000000000
R13: 00007ff61fe16038 R14: 00007ff61fe15fa0 R15: 00007ffdf473f928
 </TASK>
(syz.4.719,10360,1):ocfs2_block_check_validate:402 ERROR: CRC32 failed: stored: 0x438, computed 0x1cec3d0f. Applying ECC.
(syz.4.719,10360,1):ocfs2_block_check_validate:416 ERROR: Fixed CRC32 failed: stored: 0x438, computed 0x1cec3d0f
(syz.4.719,10360,0):ocfs2_read_quota_phys_block:160 ERROR: status = -5
(syz.4.719,10360,1):ocfs2_quota_read:201 ERROR: status = -5
Quota error (device loop4): find_tree_dqentry: Can't read quota tree block 4
Quota error (device loop4): qtree_read_dquot: Can't read quota structure for id 0
(syz.4.719,10360,0):ocfs2_acquire_dquot:890 ERROR: status = -5
(syz.4.719,10360,0):ocfs2_mknod:318 ERROR: status = -5
(syz.4.719,10360,0):ocfs2_mknod:506 ERROR: status = -5
(syz.4.719,10360,0):ocfs2_create:679 ERROR: status = -5

Crashes (5):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/03/14 06:58 upstream 1c9982b49613 ee8d34d6 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root possible deadlock in dqget
2026/02/25 11:31 upstream 7dff99b35460 94a9671e .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs possible deadlock in dqget
2026/01/20 00:51 upstream 24d479d26b25 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root possible deadlock in dqget
2026/02/23 08:24 linux-next d4906ae14a5f 6e7b5511 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root possible deadlock in dqget
2026/02/10 12:18 linux-next 132737e360b4 91d776d3 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root possible deadlock in dqget
* Struck through repros no longer work on HEAD.