possible deadlock in ocfs2_reflink

Status: upstream: reported on 2026/07/31 10:33
Reported-by: syzbot+4e92af9ecc77271379ce@syzkaller.appspotmail.com
First crash: 18h42m, last: 2h19m
▶ ▼ 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 19 4h23m 8d16h 0/3 upstream: reported on 2026/07/23 12:37
upstream possible deadlock in ocfs2_reflink ocfs2 prio:high 4 2 1d02h 2d05h 0/29 upstream: reported on 2026/07/30 00:10
linux-6.6 possible deadlock in ocfs2_reflink 4 4 20m 2d22h 0/2 upstream: reported on 2026/07/29 06:41

Sample crash report:
======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.4.2206/9665 is trying to acquire lock:
ffff88805f0f3f60 (&ocfs2_file_ip_alloc_sem_key){++++}-{3:3}, at: ocfs2_reflink+0x4cb/0x920 fs/ocfs2/refcounttree.c:4304

but task is already holding lock:
ffff88805f0f3ff8 (&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:

-> #5 (&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
       vfs_create+0x2db/0x460 fs/namei.c:3170
       do_mknodat+0x49e/0x630 fs/namei.c:4002
       __do_sys_mknod fs/namei.c:4035 [inline]
       __se_sys_mknod fs/namei.c:4033 [inline]
       __x64_sys_mknod+0x8a/0xa0 fs/namei.c:4033
       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

-> #4 (&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_shutdown_local_alloc+0x1f3/0xac0 fs/ocfs2/localalloc.c:416
       ocfs2_dismount_volume+0x1e1/0x890 fs/ocfs2/super.c:1885
       generic_shutdown_super+0x130/0x300 fs/super.c:475
       kill_block_super+0x7c/0xe0 fs/super.c:1427
       deactivate_locked_super+0x93/0xf0 fs/super.c:335
       cleanup_mnt+0x426/0x4d0 fs/namespace.c:1148
       task_work_run+0x125/0x1a0 kernel/task_work.c:188
       tracehook_notify_resume include/linux/tracehook.h:189 [inline]
       exit_to_user_mode_loop+0x10f/0x130 kernel/entry/common.c:181
       exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:214
       __syscall_exit_to_user_mode_work kernel/entry/common.c:296 [inline]
       syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:307
       do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:86
       entry_SYSCALL_64_after_hwframe+0x66/0xd0

-> #3 (sb_internal#2){.+.+}-{0:0}:
       percpu_down_read include/linux/percpu-rwsem.h:51 [inline]
       __sb_start_write include/linux/fs.h:1811 [inline]
       sb_start_intwrite include/linux/fs.h:1928 [inline]
       ocfs2_start_trans+0x2a7/0x6f0 fs/ocfs2/journal.c:372
       ocfs2_shutdown_local_alloc+0x1f3/0xac0 fs/ocfs2/localalloc.c:416
       ocfs2_dismount_volume+0x1e1/0x890 fs/ocfs2/super.c:1885
       generic_shutdown_super+0x130/0x300 fs/super.c:475
       kill_block_super+0x7c/0xe0 fs/super.c:1427
       deactivate_locked_super+0x93/0xf0 fs/super.c:335
       cleanup_mnt+0x426/0x4d0 fs/namespace.c:1148
       task_work_run+0x125/0x1a0 kernel/task_work.c:188
       tracehook_notify_resume include/linux/tracehook.h:189 [inline]
       exit_to_user_mode_loop+0x10f/0x130 kernel/entry/common.c:181
       exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:214
       __syscall_exit_to_user_mode_work kernel/entry/common.c:296 [inline]
       syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:307
       do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:86
       entry_SYSCALL_64_after_hwframe+0x66/0xd0

-> #2 (&ocfs2_sysfile_lock_key[args->fi_sysfile_type]#2){+.+.}-{3:3}:
       down_write+0x38/0x60 kernel/locking/rwsem.c:1551
       inode_lock include/linux/fs.h:787 [inline]
       ocfs2_reserve_suballoc_bits+0x16d/0x44b0 fs/ocfs2/suballoc.c:804
       ocfs2_reserve_cluster_bitmap_bits fs/ocfs2/suballoc.c:1150 [inline]
       ocfs2_reserve_clusters_with_limit+0x3b9/0xc10 fs/ocfs2/suballoc.c:1195
       ocfs2_block_group_alloc fs/ocfs2/suballoc.c:692 [inline]
       ocfs2_reserve_suballoc_bits+0x781/0x44b0 fs/ocfs2/suballoc.c:850
       ocfs2_reserve_new_metadata_blocks+0x412/0x9a0 fs/ocfs2/suballoc.c:1000
       ocfs2_expand_inline_dir fs/ocfs2/dir.c:2838 [inline]
       ocfs2_extend_dir+0xd4a/0x4b90 fs/ocfs2/dir.c:3200
       ocfs2_prepare_dir_for_insert+0x2efd/0x52b0 fs/ocfs2/dir.c:4321
       ocfs2_mknod+0x876/0x2510 fs/ocfs2/namei.c:294
       ocfs2_create+0x192/0x420 fs/ocfs2/namei.c:674
       vfs_create+0x2db/0x460 fs/namei.c:3170
       do_mknodat+0x49e/0x630 fs/namei.c:4002
       __do_sys_mknod fs/namei.c:4035 [inline]
       __se_sys_mknod fs/namei.c:4033 [inline]
       __x64_sys_mknod+0x8a/0xa0 fs/namei.c:4033
       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 (&ocfs2_sysfile_lock_key[args->fi_sysfile_type]#4){+.+.}-{3:3}:
       down_write+0x38/0x60 kernel/locking/rwsem.c:1551
       inode_lock include/linux/fs.h:787 [inline]
       ocfs2_reserve_suballoc_bits+0x16d/0x44b0 fs/ocfs2/suballoc.c:804
       ocfs2_reserve_new_metadata_blocks+0x412/0x9a0 fs/ocfs2/suballoc.c:1000
       ocfs2_expand_inline_dir fs/ocfs2/dir.c:2838 [inline]
       ocfs2_extend_dir+0xd4a/0x4b90 fs/ocfs2/dir.c:3200
       ocfs2_prepare_dir_for_insert+0x2efd/0x52b0 fs/ocfs2/dir.c:4321
       ocfs2_mknod+0x876/0x2510 fs/ocfs2/namei.c:294
       ocfs2_create+0x192/0x420 fs/ocfs2/namei.c:674
       vfs_create+0x2db/0x460 fs/namei.c:3170
       do_mknodat+0x49e/0x630 fs/namei.c:4002
       __do_sys_mknod fs/namei.c:4035 [inline]
       __se_sys_mknod fs/namei.c:4033 [inline]
       __x64_sys_mknod+0x8a/0xa0 fs/namei.c:4033
       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_file_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_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.4.2206/9665:
 #0: ffff8880767d0460 (sb_writers#19){.+.+}-{0:0}, at: mnt_want_write+0x3d/0x90 fs/namespace.c:386
 #1: ffff88805f0db488 (&type->i_mutex_dir_key#24/1){+.+.}-{3:3}, at: inode_lock_nested include/linux/fs.h:822 [inline]
 #1: ffff88805f0db488 (&type->i_mutex_dir_key#24/1){+.+.}-{3:3}, at: filename_create+0x20b/0x450 fs/namei.c:3843
 #2: ffff88805f0f42c8 (&sb->s_type->i_mutex_key#43){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:787 [inline]
 #2: ffff88805f0f42c8 (&sb->s_type->i_mutex_key#43){+.+.}-{3:3}, at: ocfs2_vfs_reflink+0x2f3/0x450 fs/ocfs2/refcounttree.c:4428
 #3: ffff88805f0f3ff8 (&oi->ip_xattr_sem){++++}-{3:3}, at: ocfs2_reflink+0x4bc/0x920 fs/ocfs2/refcounttree.c:4303

stack backtrace:
CPU: 0 PID: 9665 Comm: syz.4.2206 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: 0033:0x7f75ee5a0019
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:00007f75ec7f8028 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f75ee827fa0 RCX: 00007f75ee5a0019
RDX: 0000200000000180 RSI: 0000000040186f04 RDI: 0000000000000004
RBP: 00007f75ee63700c R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f75ee828038 R14: 00007f75ee827fa0 R15: 00007ffecc687a48
 </TASK>

Crashes (4):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
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.