possible deadlock in ocfs2_reflink

Status: upstream: reported on 2026/07/31 10:33
Reported-by: syzbot+4e92af9ecc77271379ce@syzkaller.appspotmail.com
First crash: 46d, last: 7d08h
Similar bugs (3)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-6.1 possible deadlock in ocfs2_reflink 4 77 2d19h 54d 0/3 upstream: reported on 2026/07/23 12:37
upstream possible deadlock in ocfs2_reflink prio:high ocfs2 4 14 21d 47d 0/29 upstream: reported on 2026/07/30 00:10
linux-6.6 possible deadlock in ocfs2_reflink 4 16 3d19h 48d 0/2 upstream: reported on 2026/07/29 06:41

Sample crash report:
loop5: detected capacity change from 0 to 32768
JBD2: Ignoring recovery information on journal
ocfs2: Mounting device (7,5) on (node local, slot 0) with ordered data mode.
======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.5.123/5116 is trying to acquire lock:
ffff88805ba73f60 (&ocfs2_quota_ip_alloc_sem_key){++++}-{3:3}, at: ocfs2_reflink+0x4cb/0x920 fs/ocfs2/refcounttree.c:4304

but task is already holding lock:
ffff88805ba73ff8 (&oi->ip_xattr_sem){++++}-{3:3}, at: ocfs2_reflink+0x4bc/0x920 fs/ocfs2/refcounttree.c:4303

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #3 (&oi->ip_xattr_sem){++++}-{3:3}:
       down_read+0x44/0x2e0 kernel/locking/rwsem.c:1498
       ocfs2_init_acl+0x307/0x770 fs/ocfs2/acl.c:365
       ocfs2_mknod+0x15de/0x2510 fs/ocfs2/namei.c:410
       ocfs2_create+0x192/0x420 fs/ocfs2/namei.c:674
       lookup_open fs/namei.c:3513 [inline]
       open_last_lookups fs/namei.c:3583 [inline]
       path_openat+0x120a/0x2fb0 fs/namei.c:3790
       do_filp_open+0x1df/0x400 fs/namei.c:3820
       do_sys_openat2+0x14b/0x500 fs/open.c:1255
       do_sys_open fs/open.c:1271 [inline]
       __do_sys_openat fs/open.c:1287 [inline]
       __se_sys_openat fs/open.c:1282 [inline]
       __x64_sys_openat+0x135/0x160 fs/open.c:1282
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x66/0xd0

-> #2 (&journal->j_trans_barrier){.+.+}-{3:3}:
       down_read+0x44/0x2e0 kernel/locking/rwsem.c:1498
       ocfs2_start_trans+0x3a6/0x6f0 fs/ocfs2/journal.c:374
       ocfs2_mknod+0xf70/0x2510 fs/ocfs2/namei.c:361
       ocfs2_create+0x192/0x420 fs/ocfs2/namei.c:674
       lookup_open fs/namei.c:3513 [inline]
       open_last_lookups fs/namei.c:3583 [inline]
       path_openat+0x120a/0x2fb0 fs/namei.c:3790
       do_filp_open+0x1df/0x400 fs/namei.c:3820
       do_sys_openat2+0x14b/0x500 fs/open.c:1255
       do_sys_open fs/open.c:1271 [inline]
       __do_sys_openat fs/open.c:1287 [inline]
       __se_sys_openat fs/open.c:1282 [inline]
       __x64_sys_openat+0x135/0x160 fs/open.c:1282
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x66/0xd0

-> #1 (sb_internal#3){.+.+}-{0:0}:
       percpu_down_read include/linux/percpu-rwsem.h:51 [inline]
       __sb_start_write include/linux/fs.h:1817 [inline]
       sb_start_intwrite include/linux/fs.h:1934 [inline]
       ocfs2_start_trans+0x2a7/0x6f0 fs/ocfs2/journal.c:372
       ocfs2_acquire_dquot+0x6c0/0xb30 fs/ocfs2/quota_global.c:848
       dqget+0x713/0xbb0 fs/quota/dquot.c:1010
       __dquot_initialize+0x3a9/0xd00 fs/quota/dquot.c:1539
       ocfs2_get_init_inode+0x144/0x1b0 fs/ocfs2/namei.c:202
       ocfs2_mknod+0x8c1/0x2510 fs/ocfs2/namei.c:310
       ocfs2_create+0x192/0x420 fs/ocfs2/namei.c:674
       lookup_open fs/namei.c:3513 [inline]
       open_last_lookups fs/namei.c:3583 [inline]
       path_openat+0x120a/0x2fb0 fs/namei.c:3790
       do_filp_open+0x1df/0x400 fs/namei.c:3820
       do_sys_openat2+0x14b/0x500 fs/open.c:1255
       do_sys_open fs/open.c:1271 [inline]
       __do_sys_openat fs/open.c:1287 [inline]
       __se_sys_openat fs/open.c:1282 [inline]
       __x64_sys_openat+0x135/0x160 fs/open.c:1282
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x66/0xd0

-> #0 (&ocfs2_quota_ip_alloc_sem_key){++++}-{3:3}:
       check_prev_add kernel/locking/lockdep.c:3053 [inline]
       check_prevs_add kernel/locking/lockdep.c:3172 [inline]
       validate_chain kernel/locking/lockdep.c:3788 [inline]
       __lock_acquire+0x2c66/0x7b50 kernel/locking/lockdep.c:5012
       lock_acquire+0x19e/0x400 kernel/locking/lockdep.c:5623
       down_write+0x38/0x60 kernel/locking/rwsem.c:1551
       ocfs2_reflink+0x4cb/0x920 fs/ocfs2/refcounttree.c:4304
       ocfs2_vfs_reflink+0x333/0x450 fs/ocfs2/refcounttree.c:4431
       ocfs2_reflink_ioctl+0x39c/0x440 fs/ocfs2/refcounttree.c:4471
       ocfs2_ioctl+0x586/0x7a0 fs/ocfs2/ioctl.c:913
       vfs_ioctl fs/ioctl.c:51 [inline]
       __do_sys_ioctl fs/ioctl.c:874 [inline]
       __se_sys_ioctl+0xfa/0x170 fs/ioctl.c:860
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x66/0xd0

other info that might help us debug this:

Chain exists of:
  &ocfs2_quota_ip_alloc_sem_key --> &journal->j_trans_barrier --> &oi->ip_xattr_sem

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&oi->ip_xattr_sem);
                               lock(&journal->j_trans_barrier);
                               lock(&oi->ip_xattr_sem);
  lock(&ocfs2_quota_ip_alloc_sem_key);

 *** DEADLOCK ***

4 locks held by syz.5.123/5116:
 #0: ffff88807d70c460 (sb_writers#16){.+.+}-{0:0}, at: mnt_want_write+0x3d/0x90 fs/namespace.c:386
 #1: ffff88805f8cdf48 (&type->i_mutex_dir_key#11/1){+.+.}-{3:3}, at: inode_lock_nested include/linux/fs.h:828 [inline]
 #1: ffff88805f8cdf48 (&type->i_mutex_dir_key#11/1){+.+.}-{3:3}, at: filename_create+0x20b/0x450 fs/namei.c:3886
 #2: ffff88805ba742c8 (&sb->s_type->i_mutex_key#24){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:793 [inline]
 #2: ffff88805ba742c8 (&sb->s_type->i_mutex_key#24){+.+.}-{3:3}, at: ocfs2_vfs_reflink+0x2f3/0x450 fs/ocfs2/refcounttree.c:4428
 #3: ffff88805ba73ff8 (&oi->ip_xattr_sem){++++}-{3:3}, at: ocfs2_reflink+0x4bc/0x920 fs/ocfs2/refcounttree.c:4303

stack backtrace:
CPU: 0 PID: 5116 Comm: syz.5.123 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0x188/0x250 lib/dump_stack.c:106
 check_noncircular+0x296/0x330 kernel/locking/lockdep.c:2133
 check_prev_add kernel/locking/lockdep.c:3053 [inline]
 check_prevs_add kernel/locking/lockdep.c:3172 [inline]
 validate_chain kernel/locking/lockdep.c:3788 [inline]
 __lock_acquire+0x2c66/0x7b50 kernel/locking/lockdep.c:5012
 lock_acquire+0x19e/0x400 kernel/locking/lockdep.c:5623
 down_write+0x38/0x60 kernel/locking/rwsem.c:1551
 ocfs2_reflink+0x4cb/0x920 fs/ocfs2/refcounttree.c:4304
 ocfs2_vfs_reflink+0x333/0x450 fs/ocfs2/refcounttree.c:4431
 ocfs2_reflink_ioctl+0x39c/0x440 fs/ocfs2/refcounttree.c:4471
 ocfs2_ioctl+0x586/0x7a0 fs/ocfs2/ioctl.c:913
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:874 [inline]
 __se_sys_ioctl+0xfa/0x170 fs/ioctl.c:860
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f7d1f31d159
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:00007f7d1d575028 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f7d1f5a4fa0 RCX: 00007f7d1f31d159
RDX: 00002000000001c0 RSI: 0000000040186f04 RDI: 0000000000000004
RBP: 00007f7d1f3b4024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f7d1f5a5038 R14: 00007f7d1f5a4fa0 R15: 00007ffe0d266a18
 </TASK>

Crashes (15):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/09/08 05:54 linux-5.15.y 0996e0926f6b 680aa3e1 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan possible deadlock in ocfs2_reflink
2026/09/07 15:16 linux-5.15.y 0996e0926f6b 680aa3e1 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan possible deadlock in ocfs2_reflink
2026/09/05 04:00 linux-5.15.y 0996e0926f6b 4f7b22a0 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan possible deadlock in ocfs2_reflink
2026/09/02 21:05 linux-5.15.y 0996e0926f6b 85995287 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan possible deadlock in ocfs2_reflink
2026/08/25 00:04 linux-5.15.y 945fa863f02c 614e416a .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan possible deadlock in ocfs2_reflink
2026/08/16 18:11 linux-5.15.y aabd761612db 746171ee .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan possible deadlock in ocfs2_reflink
2026/08/15 06:14 linux-5.15.y aabd761612db 746171ee .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan possible deadlock in ocfs2_reflink
2026/08/04 22:28 linux-5.15.y 6e2fd6534337 d4abbeac .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan possible deadlock in ocfs2_reflink
2026/08/03 15:00 linux-5.15.y 6e2fd6534337 6b7c9f71 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan possible deadlock in ocfs2_reflink
2026/08/03 15:00 linux-5.15.y 6e2fd6534337 6b7c9f71 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan possible deadlock in ocfs2_reflink
2026/08/03 14:59 linux-5.15.y 6e2fd6534337 6b7c9f71 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan possible deadlock in ocfs2_reflink
2026/08/01 02:55 linux-5.15.y 6e2fd6534337 e611ffe1 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan possible deadlock in ocfs2_reflink
2026/08/01 02:55 linux-5.15.y 6e2fd6534337 e611ffe1 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan possible deadlock in ocfs2_reflink
2026/08/01 01:34 linux-5.15.y 6e2fd6534337 7664cf44 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan possible deadlock in ocfs2_reflink
2026/07/31 10:32 linux-5.15.y 6e2fd6534337 aaffb173 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan possible deadlock in ocfs2_reflink
* Struck through repros no longer work on HEAD.