possible deadlock in ocfs2_reflink

Status: upstream: reported on 2026/07/29 06:41
Reported-by: syzbot+9af42738b9b5aee70008@syzkaller.appspotmail.com
First crash: 53d, last: 9d04h
▶ ▼ Similar bugs (3)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-5.15 possible deadlock in ocfs2_reflink 4 15 12d 51d 0/3 upstream: reported on 2026/07/31 10:33
linux-6.1 possible deadlock in ocfs2_reflink 4 77 8d04h 59d 0/3 upstream: reported on 2026/07/23 12:37
upstream possible deadlock in ocfs2_reflink prio:high ocfs2 4 14 27d 52d 0/29 upstream: reported on 2026/07/30 00:10

Sample crash report:
======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.7.3889/19736 is trying to acquire lock:
ffff88804f0c3120 (&ocfs2_file_ip_alloc_sem_key){++++}-{3:3}, at: ocfs2_reflink+0x4cf/0x920 fs/ocfs2/refcounttree.c:4277

but task is already holding lock:
ffff88804f0c31b8 (&oi->ip_xattr_sem){++++}-{3:3}, at: ocfs2_reflink+0x4c0/0x920 fs/ocfs2/refcounttree.c:4276

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+0x46/0x2e0 kernel/locking/rwsem.c:1520
       ocfs2_init_acl+0x30a/0x770 fs/ocfs2/acl.c:366
       ocfs2_mknod+0x1427/0x2310 fs/ocfs2/namei.c:410
       ocfs2_mkdir+0x196/0x430 fs/ocfs2/namei.c:657
       vfs_mkdir+0x2a5/0x470 fs/namei.c:4168
       do_mkdirat+0x1dc/0x450 fs/namei.c:4191
       __do_sys_mkdirat fs/namei.c:4206 [inline]
       __se_sys_mkdirat fs/namei.c:4204 [inline]
       __x64_sys_mkdirat+0x89/0xa0 fs/namei.c:4204
       do_syscall_x64 arch/x86/entry/common.c:46 [inline]
       do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76
       entry_SYSCALL_64_after_hwframe+0x68/0xd2

-> #2 (&journal->j_trans_barrier){.+.+}-{3:3}:
       down_read+0x46/0x2e0 kernel/locking/rwsem.c:1520
       ocfs2_start_trans+0x3a8/0x6f0 fs/ocfs2/journal.c:372
       ocfs2_mknod+0xf33/0x2310 fs/ocfs2/namei.c:361
       ocfs2_mkdir+0x196/0x430 fs/ocfs2/namei.c:657
       vfs_mkdir+0x2a5/0x470 fs/namei.c:4168
       do_mkdirat+0x1dc/0x450 fs/namei.c:4191
       __do_sys_mkdirat fs/namei.c:4206 [inline]
       __se_sys_mkdirat fs/namei.c:4204 [inline]
       __x64_sys_mkdirat+0x89/0xa0 fs/namei.c:4204
       do_syscall_x64 arch/x86/entry/common.c:46 [inline]
       do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76
       entry_SYSCALL_64_after_hwframe+0x68/0xd2

-> #1 (sb_internal#2){.+.+}-{0:0}:
       __lock_release kernel/locking/lockdep.c:5468 [inline]
       lock_release+0x332/0x8c0 kernel/locking/lockdep.c:5774
       up_write+0x2d/0x410 kernel/locking/rwsem.c:1625
       inode_unlock include/linux/fs.h:809 [inline]
       ocfs2_free_ac_resource fs/ocfs2/suballoc.c:126 [inline]
       ocfs2_free_alloc_context+0x97/0x1a0 fs/ocfs2/suballoc.c:140
       ocfs2_write_begin_nolock+0x43f6/0x4480 fs/ocfs2/aops.c:1827
       ocfs2_write_begin+0x1bb/0x310 fs/ocfs2/aops.c:1906
       generic_perform_write+0x2fe/0x5c0 mm/filemap.c:4036
       ocfs2_file_write_iter+0x1724/0x1ef0 fs/ocfs2/file.c:2468
       call_write_iter include/linux/fs.h:2018 [inline]
       new_sync_write fs/read_write.c:491 [inline]
       vfs_write+0x474/0x9a0 fs/read_write.c:584
       ksys_pwrite64 fs/read_write.c:699 [inline]
       __do_sys_pwrite64 fs/read_write.c:709 [inline]
       __se_sys_pwrite64 fs/read_write.c:706 [inline]
       __x64_sys_pwrite64+0x198/0x220 fs/read_write.c:706
       do_syscall_x64 arch/x86/entry/common.c:46 [inline]
       do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76
       entry_SYSCALL_64_after_hwframe+0x68/0xd2

-> #0 (&ocfs2_file_ip_alloc_sem_key){++++}-{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+0x37ef/0x7d80 kernel/locking/lockdep.c:5137
       lock_acquire+0x19e/0x420 kernel/locking/lockdep.c:5754
       down_write+0x97/0x200 kernel/locking/rwsem.c:1573
       ocfs2_reflink+0x4cf/0x920 fs/ocfs2/refcounttree.c:4277
       ocfs2_vfs_reflink+0x333/0x450 fs/ocfs2/refcounttree.c:4404
       ocfs2_reflink_ioctl+0x3a0/0x450 fs/ocfs2/refcounttree.c:4444
       ocfs2_ioctl+0x5b9/0x7e0 fs/ocfs2/ioctl.c:923
       vfs_ioctl fs/ioctl.c:51 [inline]
       __do_sys_ioctl fs/ioctl.c:871 [inline]
       __se_sys_ioctl+0xfd/0x170 fs/ioctl.c:857
       do_syscall_x64 arch/x86/entry/common.c:46 [inline]
       do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76
       entry_SYSCALL_64_after_hwframe+0x68/0xd2

other info that might help us debug this:

Chain exists of:
  &ocfs2_file_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_file_ip_alloc_sem_key);

 *** DEADLOCK ***

4 locks held by syz.7.3889/19736:
 #0: ffff88807be00418 (sb_writers#21){.+.+}-{0:0}, at: mnt_want_write+0x41/0x90 fs/namespace.c:412
 #1: ffff88805da41818 (&type->i_mutex_dir_key#11/1){+.+.}-{3:3}, at: inode_lock_nested include/linux/fs.h:839 [inline]
 #1: ffff88805da41818 (&type->i_mutex_dir_key#11/1){+.+.}-{3:3}, at: filename_create+0x20f/0x450 fs/namei.c:3937
 #2: ffff88804f0c3498 (&sb->s_type->i_mutex_key#27){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:804 [inline]
 #2: ffff88804f0c3498 (&sb->s_type->i_mutex_key#27){+.+.}-{3:3}, at: ocfs2_vfs_reflink+0x2f3/0x450 fs/ocfs2/refcounttree.c:4401
 #3: ffff88804f0c31b8 (&oi->ip_xattr_sem){++++}-{3:3}, at: ocfs2_reflink+0x4c0/0x920 fs/ocfs2/refcounttree.c:4276

stack backtrace:
CPU: 0 PID: 19736 Comm: syz.7.3889 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0x18c/0x250 lib/dump_stack.c:106
 check_noncircular+0x2fc/0x400 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+0x37ef/0x7d80 kernel/locking/lockdep.c:5137
 lock_acquire+0x19e/0x420 kernel/locking/lockdep.c:5754
 down_write+0x97/0x200 kernel/locking/rwsem.c:1573
 ocfs2_reflink+0x4cf/0x920 fs/ocfs2/refcounttree.c:4277
 ocfs2_vfs_reflink+0x333/0x450 fs/ocfs2/refcounttree.c:4404
 ocfs2_reflink_ioctl+0x3a0/0x450 fs/ocfs2/refcounttree.c:4444
 ocfs2_ioctl+0x5b9/0x7e0 fs/ocfs2/ioctl.c:923
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:871 [inline]
 __se_sys_ioctl+0xfd/0x170 fs/ioctl.c:857
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f1804f9e159
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:00007f1805f01028 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f1805225fa0 RCX: 00007f1804f9e159
RDX: 00002000000001c0 RSI: 0000000040186f04 RDI: 0000000000000004
RBP: 00007f180503503b R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f1805226038 R14: 00007f1805225fa0 R15: 00007ffe63f6b208
 </TASK>

Crashes (16):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/09/11 19:13 linux-6.6.y 8b73de7da85f b6a5eeb7 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan possible deadlock in ocfs2_reflink
2026/09/11 19:13 linux-6.6.y 8b73de7da85f b6a5eeb7 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan possible deadlock in ocfs2_reflink
2026/08/26 02:00 linux-6.6.y dc6160265ffc 6a91adb4 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan possible deadlock in ocfs2_reflink
2026/08/26 02:00 linux-6.6.y dc6160265ffc 6a91adb4 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan possible deadlock in ocfs2_reflink
2026/08/25 12:42 linux-6.6.y dc6160265ffc a9a1fc32 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan possible deadlock in ocfs2_reflink
2026/08/25 12:41 linux-6.6.y dc6160265ffc a9a1fc32 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan possible deadlock in ocfs2_reflink
2026/08/06 15:20 linux-6.6.y aa0e49877a2e c38879ea .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan possible deadlock in ocfs2_reflink
2026/08/06 15:18 linux-6.6.y aa0e49877a2e c38879ea .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan possible deadlock in ocfs2_reflink
2026/08/04 00:58 linux-6.6.y aa0e49877a2e 9451e17e .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan possible deadlock in ocfs2_reflink
2026/08/04 00:57 linux-6.6.y aa0e49877a2e 9451e17e .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan possible deadlock in ocfs2_reflink
2026/08/03 13:23 linux-6.6.y aa0e49877a2e 6b7c9f71 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan possible deadlock in ocfs2_reflink
2026/08/03 12:46 linux-6.6.y aa0e49877a2e 6b7c9f71 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan possible deadlock in ocfs2_reflink
2026/08/01 04:55 linux-6.6.y a1153c0deb44 e611ffe1 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan possible deadlock in ocfs2_reflink
2026/07/31 01:28 linux-6.6.y a1153c0deb44 aaffb173 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan possible deadlock in ocfs2_reflink
2026/07/31 01:27 linux-6.6.y a1153c0deb44 aaffb173 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan possible deadlock in ocfs2_reflink
2026/07/29 06:40 linux-6.6.y c5596480c50e 19622d9d .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan possible deadlock in ocfs2_reflink
* Struck through repros no longer work on HEAD.