syzbot


possible deadlock in ocfs2_lock_refcount_tree (4)

Status: upstream: reported on 2026/04/24 03:20
Subsystems: ocfs2
[Documentation on labels]
Reported-by: syzbot+7aaed0c45ce3fceccefa@syzkaller.appspotmail.com
First crash: 7d22h, last: 3d13h
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 (6)
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 231d 590d 0/3 auto-obsoleted due to no activity on 2025/12/04 20:56
upstream possible deadlock in ocfs2_lock_refcount_tree (3) ocfs2 4 1 220d 216d 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 94d 532d 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 581d 598d 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 425d 473d 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 112d 131d 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.0.0/5342 is trying to acquire lock:
ffff8880126e4890 (&new->rf_sem){+.+.}-{4:4}, at: __ocfs2_lock_refcount_tree fs/ocfs2/refcounttree.c:428 [inline]
ffff8880126e4890 (&new->rf_sem){+.+.}-{4:4}, at: ocfs2_lock_refcount_tree+0x1b7/0xa40 fs/ocfs2/refcounttree.c:463

but task is already holding lock:
ffff888047f7cfa0 (&ocfs2_sysfile_lock_key[ORPHAN_DIR_SYSTEM_INODE]){+.+.}-{4:4}, at: inode_lock include/linux/fs.h:1029 [inline]
ffff888047f7cfa0 (&ocfs2_sysfile_lock_key[ORPHAN_DIR_SYSTEM_INODE]){+.+.}-{4:4}, at: ocfs2_wipe_inode fs/ocfs2/inode.c:854 [inline]
ffff888047f7cfa0 (&ocfs2_sysfile_lock_key[ORPHAN_DIR_SYSTEM_INODE]){+.+.}-{4:4}, at: ocfs2_delete_inode fs/ocfs2/inode.c:1157 [inline]
ffff888047f7cfa0 (&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
       iter_file_splice_write+0x9a1/0x10f0 fs/splice.c:736
       do_splice_from fs/splice.c:936 [inline]
       direct_splice_actor+0x101/0x160 fs/splice.c:1159
       splice_direct_to_actor+0x53a/0xc70 fs/splice.c:1103
       do_splice_direct_actor fs/splice.c:1202 [inline]
       do_splice_direct+0x195/0x290 fs/splice.c:1228
       do_sendfile+0x535/0x7d0 fs/read_write.c:1372
       __do_sys_sendfile64 fs/read_write.c:1433 [inline]
       __se_sys_sendfile64+0x144/0x1a0 fs/read_write.c:1419
       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_clone_file_range+0x42c/0x7b0 fs/remap_range.c:403
       ioctl_file_clone fs/ioctl.c:239 [inline]
       ioctl_file_clone_range fs/ioctl.c:257 [inline]
       do_vfs_ioctl+0xe0f/0x1530 fs/ioctl.c:544
       __do_sys_ioctl fs/ioctl.c:595 [inline]
       __se_sys_ioctl+0x82/0x170 fs/ioctl.c:583
       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+0xed/0x480 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.0.0/5342:
 #0: ffff8880121c0bc0 (&osb->nfs_sync_rwlock){.+.+}-{4:4}, at: ocfs2_nfs_sync_lock+0x106/0x270 fs/ocfs2/dlmglue.c:2875
 #1: ffff888047f7cfa0 (&ocfs2_sysfile_lock_key[ORPHAN_DIR_SYSTEM_INODE]){+.+.}-{4:4}, at: inode_lock include/linux/fs.h:1029 [inline]
 #1: ffff888047f7cfa0 (&ocfs2_sysfile_lock_key[ORPHAN_DIR_SYSTEM_INODE]){+.+.}-{4:4}, at: ocfs2_wipe_inode fs/ocfs2/inode.c:854 [inline]
 #1: ffff888047f7cfa0 (&ocfs2_sysfile_lock_key[ORPHAN_DIR_SYSTEM_INODE]){+.+.}-{4:4}, at: ocfs2_delete_inode fs/ocfs2/inode.c:1157 [inline]
 #1: ffff888047f7cfa0 (&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: 5342 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+0xed/0x480 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: 0033:0x7fc75f39cdd9
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:00007ffcd96996e8 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4
RAX: 0000000000000000 RBX: 00007ffcd96997d0 RCX: 00007fc75f39cdd9
RDX: 0000000000000000 RSI: 000000000000001e RDI: 0000000000000003
RBP: 0000000000019026 R08: 0000000000000001 R09: 0000000000000000
R10: 00007fc75f1ff02c R11: 0000000000000246 R12: 00007ffcd9699810
R13: 00007fc75f615fac R14: 00000000000195f8 R15: 00007fc75f615fa0
 </TASK>

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
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.