syzbot


possible deadlock in dqget

Status: upstream: reported on 2025/06/20 12:37
Reported-by: syzbot+800d0bb0e3680e9c707e@syzkaller.appspotmail.com
First crash: 205d, last: 4d11h
Similar bugs (3)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-6.1 possible deadlock in dqget 4 1 349d 349d 0/3 auto-obsoleted due to no activity on 2025/05/07 22:20
upstream possible deadlock in dqget ext4 ocfs2 4 C error 100357 14d 467d 29/29 fixed on 2026/01/07 12:29
linux-6.1 possible deadlock in dqget (2) 4 11 81d 195d 0/3 upstream: reported on 2025/06/30 17:34

Sample crash report:
JBD2: Ignoring recovery information on journal
ocfs2: Mounting device (7,9) on (node local, slot 0) with ordered data mode.
======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.9.543/9379 is trying to acquire lock:
ffff88805d0902a8 (&dquot->dq_lock){+.+.}-{3:3}, at: wait_on_dquot fs/quota/dquot.c:358 [inline]
ffff88805d0902a8 (&dquot->dq_lock){+.+.}-{3:3}, at: dqget+0x6fc/0xeb0 fs/quota/dquot.c:985

but task is already holding lock:
ffff888054d0a658 (&ocfs2_sysfile_lock_key[args->fi_sysfile_type]#2){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:804 [inline]
ffff888054d0a658 (&ocfs2_sysfile_lock_key[args->fi_sysfile_type]#2){+.+.}-{3:3}, at: ocfs2_reserve_suballoc_bits+0x165/0x4360 fs/ocfs2/suballoc.c:782

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #3 (&ocfs2_sysfile_lock_key[args->fi_sysfile_type]#2){+.+.}-{3:3}:
       down_write+0x97/0x1f0 kernel/locking/rwsem.c:1573
       inode_lock include/linux/fs.h:804 [inline]
       ocfs2_remove_inode fs/ocfs2/inode.c:655 [inline]
       ocfs2_wipe_inode fs/ocfs2/inode.c:818 [inline]
       ocfs2_delete_inode fs/ocfs2/inode.c:1079 [inline]
       ocfs2_evict_inode+0x1313/0x3e70 fs/ocfs2/inode.c:1219
       evict+0x486/0x870 fs/inode.c:705
       do_unlinkat+0x37b/0x570 fs/namei.c:4406
       __do_sys_unlinkat fs/namei.c:4442 [inline]
       __se_sys_unlinkat fs/namei.c:4435 [inline]
       __x64_sys_unlinkat+0xd5/0xe0 fs/namei.c:4435
       do_syscall_x64 arch/x86/entry/common.c:51 [inline]
       do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
       entry_SYSCALL_64_after_hwframe+0x68/0xd2

-> #2 (&ocfs2_sysfile_lock_key[args->fi_sysfile_type]){+.+.}-{3:3}:
       down_write+0x97/0x1f0 kernel/locking/rwsem.c:1573
       inode_lock include/linux/fs.h:804 [inline]
       ocfs2_del_inode_from_orphan+0x135/0x740 fs/ocfs2/namei.c:2716
       ocfs2_dio_end_io_write fs/ocfs2/aops.c:2333 [inline]
       ocfs2_dio_end_io+0x47b/0x10f0 fs/ocfs2/aops.c:2431
       dio_complete+0x254/0x710 fs/direct-io.c:282
       __blockdev_direct_IO+0x2dc8/0x3420 fs/direct-io.c:1308
       ocfs2_direct_IO+0x240/0x2b0 fs/ocfs2/aops.c:2468
       generic_file_direct_write+0x1d4/0x3e0 mm/filemap.c:3956
       __generic_file_write_iter+0x11b/0x230 mm/filemap.c:4112
       ocfs2_file_write_iter+0x1582/0x1d00 fs/ocfs2/file.c:2468
       do_iter_readv_writev fs/read_write.c:-1 [inline]
       do_iter_write+0x79a/0xc70 fs/read_write.c:860
       iter_file_splice_write+0x66f/0xc50 fs/splice.c:736
       do_splice_from fs/splice.c:933 [inline]
       direct_splice_actor+0xe8/0x130 fs/splice.c:1142
       splice_direct_to_actor+0x2f0/0x870 fs/splice.c:1088
       do_splice_direct+0x1b7/0x2c0 fs/splice.c:1194
       do_sendfile+0x5dc/0xf70 fs/read_write.c:1254
       __do_sys_sendfile64 fs/read_write.c:1322 [inline]
       __se_sys_sendfile64+0x13f/0x190 fs/read_write.c:1308
       do_syscall_x64 arch/x86/entry/common.c:51 [inline]
       do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
       entry_SYSCALL_64_after_hwframe+0x68/0xd2

-> #1 (&ocfs2_quota_ip_alloc_sem_key){++++}-{3:3}:
       down_write+0x97/0x1f0 kernel/locking/rwsem.c:1573
       ocfs2_create_local_dquot+0x1a4/0x1790 fs/ocfs2/quota_local.c:1224
       ocfs2_acquire_dquot+0x7cf/0xaf0 fs/ocfs2/quota_global.c:871
       dqget+0x77c/0xeb0 fs/quota/dquot.c:990
       ocfs2_setattr+0xf59/0x1b20 fs/ocfs2/file.c:1242
       notify_change+0xb0d/0xe10 fs/attr.c:499
       chown_common+0x3f9/0x5a0 fs/open.c:783
       vfs_fchown fs/open.c:851 [inline]
       ksys_fchown+0xed/0x160 fs/open.c:862
       __do_sys_fchown fs/open.c:870 [inline]
       __se_sys_fchown fs/open.c:868 [inline]
       __x64_sys_fchown+0x7a/0x90 fs/open.c:868
       do_syscall_x64 arch/x86/entry/common.c:51 [inline]
       do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
       entry_SYSCALL_64_after_hwframe+0x68/0xd2

-> #0 (&dquot->dq_lock){+.+.}-{3:3}:
       check_prev_add kernel/locking/lockdep.c:3134 [inline]
       check_prevs_add kernel/locking/lockdep.c:3253 [inline]
       validate_chain kernel/locking/lockdep.c:3869 [inline]
       __lock_acquire+0x2ddb/0x7c80 kernel/locking/lockdep.c:5137
       lock_acquire+0x197/0x410 kernel/locking/lockdep.c:5754
       __mutex_lock_common kernel/locking/mutex.c:603 [inline]
       __mutex_lock+0x129/0xcc0 kernel/locking/mutex.c:747
       wait_on_dquot fs/quota/dquot.c:358 [inline]
       dqget+0x6fc/0xeb0 fs/quota/dquot.c:985
       __dquot_initialize+0x3ba/0xcb0 fs/quota/dquot.c:1518
       ocfs2_get_init_inode+0x13c/0x1b0 fs/ocfs2/namei.c:202
       ocfs2_mknod+0x867/0x20f0 fs/ocfs2/namei.c:310
       ocfs2_create+0x196/0x410 fs/ocfs2/namei.c:674
       lookup_open fs/namei.c:3496 [inline]
       open_last_lookups fs/namei.c:3564 [inline]
       path_openat+0x1277/0x3190 fs/namei.c:3794
       do_filp_open+0x1c5/0x3d0 fs/namei.c:3824
       do_sys_openat2+0x12c/0x1c0 fs/open.c:1421
       do_sys_open fs/open.c:1436 [inline]
       __do_sys_openat fs/open.c:1452 [inline]
       __se_sys_openat fs/open.c:1447 [inline]
       __x64_sys_openat+0x139/0x160 fs/open.c:1447
       do_syscall_x64 arch/x86/entry/common.c:51 [inline]
       do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
       entry_SYSCALL_64_after_hwframe+0x68/0xd2

other info that might help us debug this:

Chain exists of:
  &dquot->dq_lock --> &ocfs2_sysfile_lock_key[args->fi_sysfile_type] --> &ocfs2_sysfile_lock_key[args->fi_sysfile_type]#2

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&ocfs2_sysfile_lock_key[args->fi_sysfile_type]#2);
                               lock(&ocfs2_sysfile_lock_key[args->fi_sysfile_type]);
                               lock(&ocfs2_sysfile_lock_key[args->fi_sysfile_type]#2);
  lock(&dquot->dq_lock);

 *** DEADLOCK ***

3 locks held by syz.9.543/9379:
 #0: ffff88802f4b0418 (sb_writers#22){.+.+}-{0:0}, at: mnt_want_write+0x41/0x90 fs/namespace.c:412
 #1: ffff88805d0f1818 (&type->i_mutex_dir_key#14){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:804 [inline]
 #1: ffff88805d0f1818 (&type->i_mutex_dir_key#14){+.+.}-{3:3}, at: open_last_lookups fs/namei.c:3561 [inline]
 #1: ffff88805d0f1818 (&type->i_mutex_dir_key#14){+.+.}-{3:3}, at: path_openat+0x7c6/0x3190 fs/namei.c:3794
 #2: ffff888054d0a658 (&ocfs2_sysfile_lock_key[args->fi_sysfile_type]#2){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:804 [inline]
 #2: ffff888054d0a658 (&ocfs2_sysfile_lock_key[args->fi_sysfile_type]#2){+.+.}-{3:3}, at: ocfs2_reserve_suballoc_bits+0x165/0x4360 fs/ocfs2/suballoc.c:782

stack backtrace:
CPU: 0 PID: 9379 Comm: syz.9.543 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x16c/0x230 lib/dump_stack.c:106
 check_noncircular+0x2bd/0x3c0 kernel/locking/lockdep.c:2187
 check_prev_add kernel/locking/lockdep.c:3134 [inline]
 check_prevs_add kernel/locking/lockdep.c:3253 [inline]
 validate_chain kernel/locking/lockdep.c:3869 [inline]
 __lock_acquire+0x2ddb/0x7c80 kernel/locking/lockdep.c:5137
 lock_acquire+0x197/0x410 kernel/locking/lockdep.c:5754
 __mutex_lock_common kernel/locking/mutex.c:603 [inline]
 __mutex_lock+0x129/0xcc0 kernel/locking/mutex.c:747
 wait_on_dquot fs/quota/dquot.c:358 [inline]
 dqget+0x6fc/0xeb0 fs/quota/dquot.c:985
 __dquot_initialize+0x3ba/0xcb0 fs/quota/dquot.c:1518
 ocfs2_get_init_inode+0x13c/0x1b0 fs/ocfs2/namei.c:202
 ocfs2_mknod+0x867/0x20f0 fs/ocfs2/namei.c:310
 ocfs2_create+0x196/0x410 fs/ocfs2/namei.c:674
 lookup_open fs/namei.c:3496 [inline]
 open_last_lookups fs/namei.c:3564 [inline]
 path_openat+0x1277/0x3190 fs/namei.c:3794
 do_filp_open+0x1c5/0x3d0 fs/namei.c:3824
 do_sys_openat2+0x12c/0x1c0 fs/open.c:1421
 do_sys_open fs/open.c:1436 [inline]
 __do_sys_openat fs/open.c:1452 [inline]
 __se_sys_openat fs/open.c:1447 [inline]
 __x64_sys_openat+0x139/0x160 fs/open.c:1447
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f78d8b8f749
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f78d998c038 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007f78d8de5fa0 RCX: 00007f78d8b8f749
RDX: 0000000000141042 RSI: 0000200000000080 RDI: ffffffffffffff9c
RBP: 00007f78d8c13f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f78d8de6038 R14: 00007f78d8de5fa0 R15: 00007ffe201c8d88
 </TASK>

Crashes (26):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/01/07 18:40 linux-6.6.y 5fa4793a2d2d d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan possible deadlock in dqget
2025/11/03 20:02 linux-6.6.y 0a805b6ea8cd 686bf657 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan possible deadlock in dqget
2025/10/29 14:36 linux-6.6.y e5bbb12db2c7 fd2207e7 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan possible deadlock in dqget
2025/10/23 15:32 linux-6.6.y 4a243110dc88 c0460fcd .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan possible deadlock in dqget
2025/10/21 02:43 linux-6.6.y f231f248323d 9832ed61 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan possible deadlock in dqget
2025/10/19 16:35 linux-6.6.y f231f248323d 1c8c8cd8 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan possible deadlock in dqget
2025/10/15 11:35 linux-6.6.y 0bbbd97a442d b6605ba8 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan possible deadlock in dqget
2025/10/13 11:27 linux-6.6.y 655054d2c3c1 b6605ba8 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan possible deadlock in dqget
2025/10/01 23:59 linux-6.6.y 147338df3487 267f56c6 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan possible deadlock in dqget
2025/09/25 10:24 linux-6.6.y 147338df3487 0abd0691 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan possible deadlock in dqget
2025/09/19 10:24 linux-6.6.y 60a9e718726f 67c37560 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan possible deadlock in dqget
2025/09/11 17:22 linux-6.6.y 60a9e718726f fdeaa69b .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan possible deadlock in dqget
2025/09/09 19:12 linux-6.6.y fe9731e10004 d291dd2d .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan possible deadlock in dqget
2025/08/01 11:51 linux-6.6.y 3a8ababb8b6a 40127d41 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan possible deadlock in dqget
2025/07/23 06:05 linux-6.6.y d96eb99e2f0e e1dd4f22 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan possible deadlock in dqget
2025/07/18 20:11 linux-6.6.y d96eb99e2f0e 7117feec .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan possible deadlock in dqget
2025/07/18 06:37 linux-6.6.y d96eb99e2f0e 88248e14 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan possible deadlock in dqget
2025/07/10 16:08 linux-6.6.y 59a2de10b81a 956bd956 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan possible deadlock in dqget
2025/07/03 04:08 linux-6.6.y 3f5b4c104b7d 115ceea7 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan possible deadlock in dqget
2025/07/02 04:01 linux-6.6.y 3f5b4c104b7d bc80e4f0 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan possible deadlock in dqget
2025/06/27 22:24 linux-6.6.y 3f5b4c104b7d fc9d8ee5 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan possible deadlock in dqget
2025/06/27 12:22 linux-6.6.y 3f5b4c104b7d 803ce19b .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan possible deadlock in dqget
2025/06/24 17:44 linux-6.6.y 6282921b6825 26d77996 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan possible deadlock in dqget
2025/06/23 21:54 linux-6.6.y 6282921b6825 e2f27c35 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan possible deadlock in dqget
2025/06/21 02:08 linux-6.6.y 6282921b6825 d6cdfb8a .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan possible deadlock in dqget
2025/06/20 12:36 linux-6.6.y 6282921b6825 804b3919 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan possible deadlock in dqget
* Struck through repros no longer work on HEAD.