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possible deadlock in ocfs2_lock_refcount_tree (4)

Status: upstream: reported on 2026/04/24 03:20
Subsystems: ocfs2
Labels: prio:high
[Documentation on labels]
Reported-by: syzbot+7aaed0c45ce3fceccefa@syzkaller.appspotmail.com
First crash: 29d, last: 4d03h
✨ AI Jobs (1)
ID Workflow Result Correct Bug Created Started Finished Revision Error
70bb43d2-4980-4ffa-ae08-085cc1a88b53 assessment-security DenialOfService: ✅ Exploitable: ❌ FilesystemTrigger: ❌ NetworkTrigger: ❌ PeripheralTrigger: ❌ RemoteTrigger: ❌ Unprivileged: ✅ UserNamespace: ✅ VMGuestTrigger: ❌ VMHostTrigger: ❌ possible deadlock in ocfs2_lock_refcount_tree (4) 2026/05/12 04:43 2026/05/12 04:43 2026/05/12 05:29 d168f2605715ec7b7ab6840d636f69c758e424d9
Discussions (1)
Title Replies (including bot) Last reply
[syzbot] [ocfs2?] possible deadlock in ocfs2_lock_refcount_tree (4) 0 (1) 2026/04/24 03:20
Similar bugs (7)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-5.15 possible deadlock in ocfs2_lock_refcount_tree 4 58 252d 612d 0/3 auto-obsoleted due to no activity on 2025/12/04 20:56
linux-6.1 possible deadlock in ocfs2_lock_refcount_tree (2) 4 1 8d17h 8d17h 0/3 upstream: reported on 2026/05/11 00:20
upstream possible deadlock in ocfs2_lock_refcount_tree (3) ocfs2 4 1 242d 238d 0/29 auto-obsoleted due to no activity on 2025/12/28 08:20
linux-6.1 possible deadlock in ocfs2_lock_refcount_tree 4 97 116d 553d 0/3 auto-obsoleted due to no activity on 2026/04/03 15:33
upstream possible deadlock in ocfs2_lock_refcount_tree ocfs2 4 5 603d 620d 0/29 auto-obsoleted due to no activity on 2025/01/01 02:27
upstream possible deadlock in ocfs2_lock_refcount_tree (2) ocfs2 4 5 447d 495d 0/29 auto-obsoleted due to no activity on 2025/06/06 14:54
linux-5.15 possible deadlock in ocfs2_lock_refcount_tree (2) 4 3 134d 153d 0/3 auto-obsoleted due to no activity on 2026/04/15 05:38

Sample crash report:
======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.0.0/5323 is trying to acquire lock:
ffff88804267d090 (&new->rf_sem){+.+.}-{4:4}, at: __ocfs2_lock_refcount_tree fs/ocfs2/refcounttree.c:428 [inline]
ffff88804267d090 (&new->rf_sem){+.+.}-{4:4}, at: ocfs2_lock_refcount_tree+0x1b7/0xa40 fs/ocfs2/refcounttree.c:463

but task is already holding lock:
ffff888047114fa0 (&ocfs2_sysfile_lock_key[ORPHAN_DIR_SYSTEM_INODE]){+.+.}-{4:4}, at: inode_lock include/linux/fs.h:1029 [inline]
ffff888047114fa0 (&ocfs2_sysfile_lock_key[ORPHAN_DIR_SYSTEM_INODE]){+.+.}-{4:4}, at: ocfs2_wipe_inode fs/ocfs2/inode.c:854 [inline]
ffff888047114fa0 (&ocfs2_sysfile_lock_key[ORPHAN_DIR_SYSTEM_INODE]){+.+.}-{4:4}, at: ocfs2_delete_inode fs/ocfs2/inode.c:1157 [inline]
ffff888047114fa0 (&ocfs2_sysfile_lock_key[ORPHAN_DIR_SYSTEM_INODE]){+.+.}-{4:4}, at: ocfs2_evict_inode+0xe97/0x43b0 fs/ocfs2/inode.c:1299

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #2 (&ocfs2_sysfile_lock_key[ORPHAN_DIR_SYSTEM_INODE]){+.+.}-{4:4}:
       down_write+0x96/0x200 kernel/locking/rwsem.c:1625
       inode_lock include/linux/fs.h:1029 [inline]
       ocfs2_del_inode_from_orphan+0x12e/0x7a0 fs/ocfs2/namei.c:2728
       ocfs2_dio_end_io_write fs/ocfs2/aops.c:2379 [inline]
       ocfs2_dio_end_io+0xf9c/0x1370 fs/ocfs2/aops.c:2418
       dio_complete+0x25b/0x790 fs/direct-io.c:281
       __blockdev_direct_IO+0x2e5d/0x34e0 fs/direct-io.c:1303
       ocfs2_direct_IO+0x251/0x2c0 fs/ocfs2/aops.c:2455
       generic_file_direct_write+0x1db/0x3e0 mm/filemap.c:4259
       __generic_file_write_iter+0x11d/0x230 mm/filemap.c:4428
       ocfs2_file_write_iter+0x1663/0x1e70 fs/ocfs2/file.c:2476
       do_iter_readv_writev+0x619/0x8c0 fs/read_write.c:-1
       vfs_writev+0x33c/0x990 fs/read_write.c:1059
       do_pwritev fs/read_write.c:1155 [inline]
       __do_sys_pwritev2 fs/read_write.c:1213 [inline]
       __se_sys_pwritev2+0x184/0x2a0 fs/read_write.c:1204
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0x15f/0xf80 arch/x86/entry/syscall_64.c:94
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #1 (&ocfs2_sysfile_lock_key[EXTENT_ALLOC_SYSTEM_INODE]){+.+.}-{4:4}:
       down_write+0x96/0x200 kernel/locking/rwsem.c:1625
       inode_lock include/linux/fs.h:1029 [inline]
       ocfs2_reserve_suballoc_bits+0x16d/0x4840 fs/ocfs2/suballoc.c:882
       ocfs2_reserve_new_metadata_blocks+0x415/0x9a0 fs/ocfs2/suballoc.c:1078
       ocfs2_add_refcount_flag+0x372/0xe60 fs/ocfs2/refcounttree.c:3674
       ocfs2_reflink_remap_extent fs/ocfs2/refcounttree.c:4554 [inline]
       ocfs2_reflink_remap_blocks+0xbb2/0x1a30 fs/ocfs2/refcounttree.c:4681
       ocfs2_remap_file_range+0x451/0x6f0 fs/ocfs2/file.c:2747
       vfs_copy_file_range+0xd80/0x1370 fs/read_write.c:1600
       __do_sys_copy_file_range fs/read_write.c:1683 [inline]
       __se_sys_copy_file_range+0x2fb/0x480 fs/read_write.c:1650
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0x15f/0xf80 arch/x86/entry/syscall_64.c:94
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #0 (&new->rf_sem){+.+.}-{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+0x106/0x350 kernel/locking/lockdep.c:5868
       down_write+0x96/0x200 kernel/locking/rwsem.c:1625
       __ocfs2_lock_refcount_tree fs/ocfs2/refcounttree.c:428 [inline]
       ocfs2_lock_refcount_tree+0x1b7/0xa40 fs/ocfs2/refcounttree.c:463
       ocfs2_commit_truncate+0xb64/0x2310 fs/ocfs2/alloc.c:7375
       ocfs2_truncate_for_delete fs/ocfs2/inode.c:701 [inline]
       ocfs2_wipe_inode fs/ocfs2/inode.c:868 [inline]
       ocfs2_delete_inode fs/ocfs2/inode.c:1157 [inline]
       ocfs2_evict_inode+0x1023/0x43b0 fs/ocfs2/inode.c:1299
       evict+0x61e/0xb10 fs/inode.c:841
       ocfs2_dentry_iput+0x24d/0x390 fs/ocfs2/dcache.c:407
       __dentry_kill+0x1a2/0x690 fs/dcache.c:718
       finish_dput+0xc9/0x480 fs/dcache.c:927
       __fput+0x691/0xa60 fs/file_table.c:518
       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+0xf3/0x4d0 kernel/entry/common.c:98
       __exit_to_user_mode_prepare include/linux/irq-entry-common.h:207 [inline]
       syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:238 [inline]
       syscall_exit_to_user_mode include/linux/entry-common.h:318 [inline]
       do_syscall_64+0x33e/0xf80 arch/x86/entry/syscall_64.c:100
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

other info that might help us debug this:

Chain exists of:
  &new->rf_sem --> &ocfs2_sysfile_lock_key[EXTENT_ALLOC_SYSTEM_INODE] --> &ocfs2_sysfile_lock_key[ORPHAN_DIR_SYSTEM_INODE]

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&ocfs2_sysfile_lock_key[ORPHAN_DIR_SYSTEM_INODE]);
                               lock(&ocfs2_sysfile_lock_key[EXTENT_ALLOC_SYSTEM_INODE]);
                               lock(&ocfs2_sysfile_lock_key[ORPHAN_DIR_SYSTEM_INODE]);
  lock(&new->rf_sem);

 *** DEADLOCK ***

2 locks held by syz.0.0/5323:
 #0: ffff888012a04bc0 (&osb->nfs_sync_rwlock){.+.+}-{4:4}, at: ocfs2_nfs_sync_lock+0x106/0x270 fs/ocfs2/dlmglue.c:2875
 #1: ffff888047114fa0 (&ocfs2_sysfile_lock_key[ORPHAN_DIR_SYSTEM_INODE]){+.+.}-{4:4}, at: inode_lock include/linux/fs.h:1029 [inline]
 #1: ffff888047114fa0 (&ocfs2_sysfile_lock_key[ORPHAN_DIR_SYSTEM_INODE]){+.+.}-{4:4}, at: ocfs2_wipe_inode fs/ocfs2/inode.c:854 [inline]
 #1: ffff888047114fa0 (&ocfs2_sysfile_lock_key[ORPHAN_DIR_SYSTEM_INODE]){+.+.}-{4:4}, at: ocfs2_delete_inode fs/ocfs2/inode.c:1157 [inline]
 #1: ffff888047114fa0 (&ocfs2_sysfile_lock_key[ORPHAN_DIR_SYSTEM_INODE]){+.+.}-{4:4}, at: ocfs2_evict_inode+0xe97/0x43b0 fs/ocfs2/inode.c:1299

stack backtrace:
CPU: 0 UID: 0 PID: 5323 Comm: syz.0.0 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
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+0x106/0x350 kernel/locking/lockdep.c:5868
 down_write+0x96/0x200 kernel/locking/rwsem.c:1625
 __ocfs2_lock_refcount_tree fs/ocfs2/refcounttree.c:428 [inline]
 ocfs2_lock_refcount_tree+0x1b7/0xa40 fs/ocfs2/refcounttree.c:463
 ocfs2_commit_truncate+0xb64/0x2310 fs/ocfs2/alloc.c:7375
 ocfs2_truncate_for_delete fs/ocfs2/inode.c:701 [inline]
 ocfs2_wipe_inode fs/ocfs2/inode.c:868 [inline]
 ocfs2_delete_inode fs/ocfs2/inode.c:1157 [inline]
 ocfs2_evict_inode+0x1023/0x43b0 fs/ocfs2/inode.c:1299
 evict+0x61e/0xb10 fs/inode.c:841
 ocfs2_dentry_iput+0x24d/0x390 fs/ocfs2/dcache.c:407
 __dentry_kill+0x1a2/0x690 fs/dcache.c:718
 finish_dput+0xc9/0x480 fs/dcache.c:927
 __fput+0x691/0xa60 fs/file_table.c:518
 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+0xf3/0x4d0 kernel/entry/common.c:98
 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:207 [inline]
 syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:238 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:318 [inline]
 do_syscall_64+0x33e/0xf80 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fd8a139ce59
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:00007ffe4a12bfb8 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4
RAX: 0000000000000000 RBX: 00007fd8a1617da0 RCX: 00007fd8a139ce59
RDX: 0000000000000000 RSI: 000000000000001e RDI: 0000000000000003
RBP: 00007fd8a1617da0 R08: 00007fd8a1616038 R09: 0000000000000000
R10: 0000000000d8083c R11: 0000000000000246 R12: 0000000000014add
R13: 00007fd8a1615fac R14: 0000000000013f24 R15: 00007ffe4a12c0c0
 </TASK>

Crashes (7):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/05/15 14:50 upstream 70eda68668d1 9cd3beaa .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root possible deadlock in ocfs2_lock_refcount_tree
2026/05/14 22:33 upstream 66182ca873a4 6ccb967e .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root possible deadlock in ocfs2_lock_refcount_tree
2026/05/14 22:33 upstream 66182ca873a4 6ccb967e .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root possible deadlock in ocfs2_lock_refcount_tree
2026/05/14 16:46 upstream e1914add2799 6ccb967e .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root possible deadlock in ocfs2_lock_refcount_tree
2026/05/12 11:50 upstream 50897c955902 07aeade5 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root possible deadlock in ocfs2_lock_refcount_tree
2026/04/24 12:54 upstream dd6c438c3e64 9cfb3ca7 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root possible deadlock in ocfs2_lock_refcount_tree
2026/04/20 03:12 upstream bea8d77e45a8 303e2802 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root possible deadlock in ocfs2_lock_refcount_tree
* Struck through repros no longer work on HEAD.