syzbot


possible deadlock in ocfs2_lock_refcount_tree (3)

Status: upstream: reported on 2025/09/23 08:30
Subsystems: ocfs2
[Documentation on labels]
Reported-by: syzbot+322e77eae942c8a32a6c@syzkaller.appspotmail.com
First crash: 4d08h, last: 4d08h
Discussions (1)
Title Replies (including bot) Last reply
[syzbot] [ocfs2?] possible deadlock in ocfs2_lock_refcount_tree (3) 0 (1) 2025/09/23 08:30
Similar bugs (4)
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 14d 374d 0/3 upstream: reported on 2024/09/14 13:53
linux-6.1 possible deadlock in ocfs2_lock_refcount_tree 4 77 15d 315d 0/3 upstream: reported on 2024/11/11 19:23
upstream possible deadlock in ocfs2_lock_refcount_tree ocfs2 4 5 365d 382d 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 209d 257d 0/29 auto-obsoleted due to no activity on 2025/06/06 14:54

Sample crash report:
debugfs: 'B1DE653C5FFC4D88B33B244AAB9EB3E9' already exists in 'ocfs2'
ocfs2: Mounting device (7,0) on (node local, slot 0) with ordered data mode.
======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.0.173/7608 is trying to acquire lock:
ffff0000c8a0b898 (&new->rf_sem){+.+.}-{4:4}, at: __ocfs2_lock_refcount_tree fs/ocfs2/refcounttree.c:428 [inline]
ffff0000c8a0b898 (&new->rf_sem){+.+.}-{4:4}, at: ocfs2_lock_refcount_tree+0x188/0x924 fs/ocfs2/refcounttree.c:463

but task is already holding lock:
ffff0000f67a22e0 (&ocfs2_file_ip_alloc_sem_key){++++}-{4:4}, at: ocfs2_truncate_file+0x30c/0x12f4 fs/ocfs2/file.c:471

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #5 (&ocfs2_file_ip_alloc_sem_key){++++}-{4:4}:
       down_write+0x50/0xc0 kernel/locking/rwsem.c:1590
       ocfs2_try_remove_refcount_tree+0xb4/0x2d8 fs/ocfs2/refcounttree.c:932
       ocfs2_xattr_set+0x460/0xe9c fs/ocfs2/xattr.c:3669
       ocfs2_set_acl+0x574/0x628 fs/ocfs2/acl.c:254
       ocfs2_iop_set_acl+0x190/0x25c fs/ocfs2/acl.c:286
       set_posix_acl fs/posix_acl.c:954 [inline]
       vfs_set_acl+0x70c/0x974 fs/posix_acl.c:1133
       do_set_acl+0xc8/0x1a8 fs/posix_acl.c:1278
       do_setxattr fs/xattr.c:633 [inline]
       filename_setxattr+0x268/0x4f8 fs/xattr.c:665
       path_setxattrat+0x2e8/0x320 fs/xattr.c:713
       __do_sys_setxattr fs/xattr.c:747 [inline]
       __se_sys_setxattr fs/xattr.c:743 [inline]
       __arm64_sys_setxattr+0xc0/0xdc fs/xattr.c:743
       __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]
       invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:49
       el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:132
       do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:151
       el0_svc+0x5c/0x254 arch/arm64/kernel/entry-common.c:744
       el0t_64_sync_handler+0x84/0x12c arch/arm64/kernel/entry-common.c:763
       el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:596

-> #4 (&oi->ip_xattr_sem){++++}-{4:4}:
       down_read+0x58/0x2f8 kernel/locking/rwsem.c:1537
       ocfs2_init_acl+0x258/0x5f0 fs/ocfs2/acl.c:366
       ocfs2_mknod+0x1028/0x1cf0 fs/ocfs2/namei.c:413
       ocfs2_create+0x190/0x474 fs/ocfs2/namei.c:676
       lookup_open fs/namei.c:3708 [inline]
       open_last_lookups fs/namei.c:3807 [inline]
       path_openat+0x12d8/0x2c40 fs/namei.c:4043
       do_filp_open+0x18c/0x36c fs/namei.c:4073
       do_sys_openat2+0x11c/0x1b4 fs/open.c:1435
       do_sys_open fs/open.c:1450 [inline]
       __do_sys_openat fs/open.c:1466 [inline]
       __se_sys_openat fs/open.c:1461 [inline]
       __arm64_sys_openat+0x120/0x158 fs/open.c:1461
       __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]
       invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:49
       el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:132
       do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:151
       el0_svc+0x5c/0x254 arch/arm64/kernel/entry-common.c:744
       el0t_64_sync_handler+0x84/0x12c arch/arm64/kernel/entry-common.c:763
       el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:596

-> #3 (jbd2_handle){++++}-{0:0}:
       start_this_handle+0xe74/0x10dc fs/jbd2/transaction.c:444
       jbd2__journal_start+0x288/0x51c fs/jbd2/transaction.c:501
       jbd2_journal_start+0x3c/0x4c fs/jbd2/transaction.c:540
       ocfs2_start_trans+0x368/0x6b0 fs/ocfs2/journal.c:374
       ocfs2_block_group_alloc fs/ocfs2/suballoc.c:685 [inline]
       ocfs2_reserve_suballoc_bits+0x630/0x3b9c fs/ocfs2/suballoc.c:834
       ocfs2_reserve_new_metadata_blocks+0x368/0x810 fs/ocfs2/suballoc.c:984
       ocfs2_mknod+0xbd8/0x1cf0 fs/ocfs2/namei.c:350
       ocfs2_create+0x190/0x474 fs/ocfs2/namei.c:676
       lookup_open fs/namei.c:3708 [inline]
       open_last_lookups fs/namei.c:3807 [inline]
       path_openat+0x12d8/0x2c40 fs/namei.c:4043
       do_filp_open+0x18c/0x36c fs/namei.c:4073
       do_sys_openat2+0x11c/0x1b4 fs/open.c:1435
       do_sys_open fs/open.c:1450 [inline]
       __do_sys_openat fs/open.c:1466 [inline]
       __se_sys_openat fs/open.c:1461 [inline]
       __arm64_sys_openat+0x120/0x158 fs/open.c:1461
       __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]
       invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:49
       el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:132
       do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:151
       el0_svc+0x5c/0x254 arch/arm64/kernel/entry-common.c:744
       el0t_64_sync_handler+0x84/0x12c arch/arm64/kernel/entry-common.c:763
       el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:596

-> #2 (&journal->j_trans_barrier){.+.+}-{4:4}:
       down_read+0x58/0x2f8 kernel/locking/rwsem.c:1537
       ocfs2_start_trans+0x35c/0x6b0 fs/ocfs2/journal.c:372
       ocfs2_block_group_alloc fs/ocfs2/suballoc.c:685 [inline]
       ocfs2_reserve_suballoc_bits+0x630/0x3b9c fs/ocfs2/suballoc.c:834
       ocfs2_reserve_new_metadata_blocks+0x368/0x810 fs/ocfs2/suballoc.c:984
       ocfs2_mknod+0xbd8/0x1cf0 fs/ocfs2/namei.c:350
       ocfs2_create+0x190/0x474 fs/ocfs2/namei.c:676
       lookup_open fs/namei.c:3708 [inline]
       open_last_lookups fs/namei.c:3807 [inline]
       path_openat+0x12d8/0x2c40 fs/namei.c:4043
       do_filp_open+0x18c/0x36c fs/namei.c:4073
       do_sys_openat2+0x11c/0x1b4 fs/open.c:1435
       do_sys_open fs/open.c:1450 [inline]
       __do_sys_openat fs/open.c:1466 [inline]
       __se_sys_openat fs/open.c:1461 [inline]
       __arm64_sys_openat+0x120/0x158 fs/open.c:1461
       __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]
       invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:49
       el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:132
       do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:151
       el0_svc+0x5c/0x254 arch/arm64/kernel/entry-common.c:744
       el0t_64_sync_handler+0x84/0x12c arch/arm64/kernel/entry-common.c:763
       el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:596

-> #1 (sb_internal#3){.+.+}-{0:0}:
       percpu_down_read_internal include/linux/percpu-rwsem.h:53 [inline]
       percpu_down_read_freezable include/linux/percpu-rwsem.h:83 [inline]
       __sb_start_write include/linux/fs.h:1799 [inline]
       sb_start_intwrite include/linux/fs.h:1982 [inline]
       ocfs2_start_trans+0x1f4/0x6b0 fs/ocfs2/journal.c:370
       ocfs2_set_refcount_tree+0x1f8/0x624 fs/ocfs2/refcounttree.c:713
       ocfs2_reflink_remap_blocks+0x518/0x14b0 fs/ocfs2/refcounttree.c:4663
       ocfs2_remap_file_range+0x3fc/0x638 fs/ocfs2/file.c:2740
       vfs_copy_file_range+0xb24/0x1058 fs/read_write.c:1591
       __do_sys_copy_file_range fs/read_write.c:1677 [inline]
       __se_sys_copy_file_range fs/read_write.c:1644 [inline]
       __arm64_sys_copy_file_range+0x308/0x5d4 fs/read_write.c:1644
       __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]
       invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:49
       el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:132
       do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:151
       el0_svc+0x5c/0x254 arch/arm64/kernel/entry-common.c:744
       el0t_64_sync_handler+0x84/0x12c arch/arm64/kernel/entry-common.c:763
       el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:596

-> #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+0x1774/0x30a4 kernel/locking/lockdep.c:5237
       lock_acquire+0x14c/0x2e0 kernel/locking/lockdep.c:5868
       down_write+0x50/0xc0 kernel/locking/rwsem.c:1590
       __ocfs2_lock_refcount_tree fs/ocfs2/refcounttree.c:428 [inline]
       ocfs2_lock_refcount_tree+0x188/0x924 fs/ocfs2/refcounttree.c:463
       ocfs2_refcount_cow_hunk fs/ocfs2/refcounttree.c:3406 [inline]
       ocfs2_refcount_cow+0x4a4/0xb6c fs/ocfs2/refcounttree.c:3467
       ocfs2_cow_file_pos+0x2b4/0x314 fs/ocfs2/file.c:366
       ocfs2_orphan_for_truncate fs/ocfs2/file.c:387 [inline]
       ocfs2_truncate_file+0x354/0x12f4 fs/ocfs2/file.c:500
       ocfs2_setattr+0x1148/0x17a0 fs/ocfs2/file.c:1212
       notify_change+0x9a4/0xc50 fs/attr.c:552
       do_truncate+0x198/0x210 fs/open.c:68
       vfs_truncate+0x398/0x444 fs/open.c:118
       do_sys_truncate+0xe4/0x1a8 fs/open.c:141
       __do_sys_truncate fs/open.c:153 [inline]
       __se_sys_truncate fs/open.c:151 [inline]
       __arm64_sys_truncate+0x5c/0x74 fs/open.c:151
       __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]
       invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:49
       el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:132
       do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:151
       el0_svc+0x5c/0x254 arch/arm64/kernel/entry-common.c:744
       el0t_64_sync_handler+0x84/0x12c arch/arm64/kernel/entry-common.c:763
       el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:596

other info that might help us debug this:

Chain exists of:
  &new->rf_sem --> &oi->ip_xattr_sem --> &ocfs2_file_ip_alloc_sem_key

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&ocfs2_file_ip_alloc_sem_key);
                               lock(&oi->ip_xattr_sem);
                               lock(&ocfs2_file_ip_alloc_sem_key);
  lock(&new->rf_sem);

 *** DEADLOCK ***

3 locks held by syz.0.173/7608:
 #0: ffff0000ff98e428 (sb_writers#17){.+.+}-{0:0}, at: mnt_want_write+0x44/0x9c fs/namespace.c:557
 #1: ffff0000f67a2640 (&sb->s_type->i_mutex_key#24){+.+.}-{4:4}, at: inode_lock_killable include/linux/fs.h:875 [inline]
 #1: ffff0000f67a2640 (&sb->s_type->i_mutex_key#24){+.+.}-{4:4}, at: do_truncate+0x164/0x210 fs/open.c:63
 #2: ffff0000f67a22e0 (&ocfs2_file_ip_alloc_sem_key){++++}-{4:4}, at: ocfs2_truncate_file+0x30c/0x12f4 fs/ocfs2/file.c:471

stack backtrace:
CPU: 0 UID: 0 PID: 7608 Comm: syz.0.173 Not tainted syzkaller #0 PREEMPT 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/30/2025
Call trace:
 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:499 (C)
 __dump_stack+0x30/0x40 lib/dump_stack.c:94
 dump_stack_lvl+0xd8/0x12c lib/dump_stack.c:120
 dump_stack+0x1c/0x28 lib/dump_stack.c:129
 print_circular_bug+0x324/0x32c kernel/locking/lockdep.c:2043
 check_noncircular+0x154/0x174 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+0x1774/0x30a4 kernel/locking/lockdep.c:5237
 lock_acquire+0x14c/0x2e0 kernel/locking/lockdep.c:5868
 down_write+0x50/0xc0 kernel/locking/rwsem.c:1590
 __ocfs2_lock_refcount_tree fs/ocfs2/refcounttree.c:428 [inline]
 ocfs2_lock_refcount_tree+0x188/0x924 fs/ocfs2/refcounttree.c:463
 ocfs2_refcount_cow_hunk fs/ocfs2/refcounttree.c:3406 [inline]
 ocfs2_refcount_cow+0x4a4/0xb6c fs/ocfs2/refcounttree.c:3467
 ocfs2_cow_file_pos+0x2b4/0x314 fs/ocfs2/file.c:366
 ocfs2_orphan_for_truncate fs/ocfs2/file.c:387 [inline]
 ocfs2_truncate_file+0x354/0x12f4 fs/ocfs2/file.c:500
 ocfs2_setattr+0x1148/0x17a0 fs/ocfs2/file.c:1212
 notify_change+0x9a4/0xc50 fs/attr.c:552
 do_truncate+0x198/0x210 fs/open.c:68
 vfs_truncate+0x398/0x444 fs/open.c:118
 do_sys_truncate+0xe4/0x1a8 fs/open.c:141
 __do_sys_truncate fs/open.c:153 [inline]
 __se_sys_truncate fs/open.c:151 [inline]
 __arm64_sys_truncate+0x5c/0x74 fs/open.c:151
 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]
 invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:49
 el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:132
 do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:151
 el0_svc+0x5c/0x254 arch/arm64/kernel/entry-common.c:744
 el0t_64_sync_handler+0x84/0x12c arch/arm64/kernel/entry-common.c:763
 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:596

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/09/19 08:19 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci c9d61056440c e2beed91 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-gce-arm64 possible deadlock in ocfs2_lock_refcount_tree
* Struck through repros no longer work on HEAD.