syzbot


possible deadlock in ocfs2_write_begin_nolock (2)

Status: upstream: reported on 2025/11/14 02:26
Reported-by: syzbot+1b7d447d81db2b0ca198@syzkaller.appspotmail.com
First crash: 6d15h, last: 6d15h
Similar bugs (4)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream possible deadlock in ocfs2_write_begin_nolock ocfs2 4 C 857 1d13h 434d 0/29 upstream: reported C repro on 2024/09/12 09:35
linux-6.1 possible deadlock in ocfs2_write_begin_nolock 4 163 16d 404d 0/3 upstream: reported on 2024/10/11 23:44
linux-6.6 possible deadlock in ocfs2_write_begin_nolock 4 3 121d 149d 0/2 auto-obsoleted due to no activity on 2025/10/30 13:30
linux-5.15 possible deadlock in ocfs2_write_begin_nolock 4 122 1d17h 389d 0/3 upstream: reported on 2024/10/27 04:30

Sample crash report:
loop8: detected capacity change from 0 to 32768
ocfs2: Mounting device (7,8) on (node local, slot 0) with ordered data mode.
======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.8.3866/23524 is trying to acquire lock:
ffff88807a756608 (sb_internal#2){.+.+}-{0:0}, at: ocfs2_write_begin_inline fs/ocfs2/aops.c:1481 [inline]
ffff88807a756608 (sb_internal#2){.+.+}-{0:0}, at: ocfs2_try_to_write_inline_data fs/ocfs2/aops.c:1584 [inline]
ffff88807a756608 (sb_internal#2){.+.+}-{0:0}, at: ocfs2_write_begin_nolock+0x1c91/0x4190 fs/ocfs2/aops.c:1670

but task is already holding lock:
ffff888058f68660 (&ocfs2_file_ip_alloc_sem_key){++++}-{3:3}, at: ocfs2_write_begin+0x199/0x310 fs/ocfs2/aops.c:1902

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #4 (&ocfs2_file_ip_alloc_sem_key){++++}-{3:3}:
       down_write+0x97/0x1f0 kernel/locking/rwsem.c:1573
       ocfs2_try_remove_refcount_tree+0xb7/0x320 fs/ocfs2/refcounttree.c:932
       ocfs2_xattr_set+0x596/0x11f0 fs/ocfs2/xattr.c:3669
       ocfs2_set_acl+0x4e1/0x590 fs/ocfs2/acl.c:254
       ocfs2_iop_set_acl+0x1ab/0x2a0 fs/ocfs2/acl.c:286
       set_posix_acl fs/posix_acl.c:956 [inline]
       vfs_set_acl+0x803/0xa60 fs/posix_acl.c:1135
       do_setxattr fs/xattr.c:627 [inline]
       path_setxattr+0x39f/0x550 fs/xattr.c:659
       __do_sys_setxattr fs/xattr.c:677 [inline]
       __se_sys_setxattr fs/xattr.c:673 [inline]
       __x64_sys_setxattr+0xbb/0xd0 fs/xattr.c:673
       do_syscall_x64 arch/x86/entry/common.c:51 [inline]
       do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
       entry_SYSCALL_64_after_hwframe+0x68/0xd2

-> #3 (&oi->ip_xattr_sem){++++}-{3:3}:
       down_read+0x46/0x2e0 kernel/locking/rwsem.c:1520
       ocfs2_init_acl+0x2fa/0x720 fs/ocfs2/acl.c:366
       ocfs2_mknod+0x12e5/0x20f0 fs/ocfs2/namei.c:410
       ocfs2_create+0x196/0x410 fs/ocfs2/namei.c:674
       lookup_open fs/namei.c:3496 [inline]
       open_last_lookups fs/namei.c:3564 [inline]
       path_openat+0x1277/0x3190 fs/namei.c:3794
       do_filp_open+0x1c5/0x3d0 fs/namei.c:3824
       do_sys_openat2+0x12c/0x1c0 fs/open.c:1419
       do_sys_open fs/open.c:1434 [inline]
       __do_sys_openat fs/open.c:1450 [inline]
       __se_sys_openat fs/open.c:1445 [inline]
       __x64_sys_openat+0x139/0x160 fs/open.c:1445
       do_syscall_x64 arch/x86/entry/common.c:51 [inline]
       do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
       entry_SYSCALL_64_after_hwframe+0x68/0xd2

-> #2 (jbd2_handle){++++}-{0:0}:
       start_this_handle+0x1e9d/0x20c0 fs/jbd2/transaction.c:448
       jbd2__journal_start+0x2bb/0x5b0 fs/jbd2/transaction.c:505
       jbd2_journal_start+0x2a/0x40 fs/jbd2/transaction.c:544
       ocfs2_start_trans+0x376/0x6c0 fs/ocfs2/journal.c:374
       ocfs2_shutdown_local_alloc+0x201/0xa10 fs/ocfs2/localalloc.c:416
       ocfs2_dismount_volume+0x1e2/0x890 fs/ocfs2/super.c:1881
       generic_shutdown_super+0x134/0x2b0 fs/super.c:693
       kill_block_super+0x44/0x90 fs/super.c:1660
       deactivate_locked_super+0x97/0x100 fs/super.c:481
       cleanup_mnt+0x429/0x4c0 fs/namespace.c:1259
       task_work_run+0x1ce/0x250 kernel/task_work.c:239
       resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
       exit_to_user_mode_loop+0xe6/0x110 kernel/entry/common.c:177
       exit_to_user_mode_prepare+0xf6/0x180 kernel/entry/common.c:210
       __syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline]
       syscall_exit_to_user_mode+0x1a/0x50 kernel/entry/common.c:302
       do_syscall_64+0x61/0xb0 arch/x86/entry/common.c:87
       entry_SYSCALL_64_after_hwframe+0x68/0xd2

-> #1 (&journal->j_trans_barrier){.+.+}-{3:3}:
       down_read+0x46/0x2e0 kernel/locking/rwsem.c:1520
       ocfs2_start_trans+0x36a/0x6c0 fs/ocfs2/journal.c:372
       ocfs2_shutdown_local_alloc+0x201/0xa10 fs/ocfs2/localalloc.c:416
       ocfs2_dismount_volume+0x1e2/0x890 fs/ocfs2/super.c:1881
       generic_shutdown_super+0x134/0x2b0 fs/super.c:693
       kill_block_super+0x44/0x90 fs/super.c:1660
       deactivate_locked_super+0x97/0x100 fs/super.c:481
       cleanup_mnt+0x429/0x4c0 fs/namespace.c:1259
       task_work_run+0x1ce/0x250 kernel/task_work.c:239
       resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
       exit_to_user_mode_loop+0xe6/0x110 kernel/entry/common.c:177
       exit_to_user_mode_prepare+0xf6/0x180 kernel/entry/common.c:210
       __syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline]
       syscall_exit_to_user_mode+0x1a/0x50 kernel/entry/common.c:302
       do_syscall_64+0x61/0xb0 arch/x86/entry/common.c:87
       entry_SYSCALL_64_after_hwframe+0x68/0xd2

-> #0 (sb_internal#2){.+.+}-{0:0}:
       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+0x2ddb/0x7c80 kernel/locking/lockdep.c:5137
       lock_acquire+0x197/0x410 kernel/locking/lockdep.c:5754
       percpu_down_read include/linux/percpu-rwsem.h:51 [inline]
       __sb_start_write include/linux/fs.h:1633 [inline]
       sb_start_intwrite include/linux/fs.h:1755 [inline]
       ocfs2_start_trans+0x26b/0x6c0 fs/ocfs2/journal.c:370
       ocfs2_write_begin_inline fs/ocfs2/aops.c:1481 [inline]
       ocfs2_try_to_write_inline_data fs/ocfs2/aops.c:1584 [inline]
       ocfs2_write_begin_nolock+0x1c91/0x4190 fs/ocfs2/aops.c:1670
       ocfs2_write_begin+0x1bc/0x310 fs/ocfs2/aops.c:1904
       generic_perform_write+0x2fb/0x5b0 mm/filemap.c:4016
       ocfs2_file_write_iter+0x1582/0x1d00 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+0x43b/0x940 fs/read_write.c:584
       ksys_write+0x147/0x250 fs/read_write.c:637
       do_syscall_x64 arch/x86/entry/common.c:51 [inline]
       do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
       entry_SYSCALL_64_after_hwframe+0x68/0xd2

other info that might help us debug this:

Chain exists of:
  sb_internal#2 --> &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);
  rlock(sb_internal#2);

 *** DEADLOCK ***

4 locks held by syz.8.3866/23524:
 #0: ffff8880463d7248 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0x2a3/0x330 fs/file.c:1040
 #1: ffff88807a756418 (sb_writers#38){.+.+}-{0:0}, at: vfs_write+0x20e/0x940 fs/read_write.c:580
 #2: ffff888058f689d8 (&sb->s_type->i_mutex_key#43){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:804 [inline]
 #2: ffff888058f689d8 (&sb->s_type->i_mutex_key#43){+.+.}-{3:3}, at: ocfs2_file_write_iter+0x40b/0x1d00 fs/ocfs2/file.c:2398
 #3: ffff888058f68660 (&ocfs2_file_ip_alloc_sem_key){++++}-{3:3}, at: ocfs2_write_begin+0x199/0x310 fs/ocfs2/aops.c:1902

stack backtrace:
CPU: 1 PID: 23524 Comm: syz.8.3866 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x16c/0x230 lib/dump_stack.c:106
 check_noncircular+0x2bd/0x3c0 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+0x2ddb/0x7c80 kernel/locking/lockdep.c:5137
 lock_acquire+0x197/0x410 kernel/locking/lockdep.c:5754
 percpu_down_read include/linux/percpu-rwsem.h:51 [inline]
 __sb_start_write include/linux/fs.h:1633 [inline]
 sb_start_intwrite include/linux/fs.h:1755 [inline]
 ocfs2_start_trans+0x26b/0x6c0 fs/ocfs2/journal.c:370
 ocfs2_write_begin_inline fs/ocfs2/aops.c:1481 [inline]
 ocfs2_try_to_write_inline_data fs/ocfs2/aops.c:1584 [inline]
 ocfs2_write_begin_nolock+0x1c91/0x4190 fs/ocfs2/aops.c:1670
 ocfs2_write_begin+0x1bc/0x310 fs/ocfs2/aops.c:1904
 generic_perform_write+0x2fb/0x5b0 mm/filemap.c:4016
 ocfs2_file_write_iter+0x1582/0x1d00 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+0x43b/0x940 fs/read_write.c:584
 ksys_write+0x147/0x250 fs/read_write.c:637
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fddcb98f6c9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fddcc882038 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007fddcbbe5fa0 RCX: 00007fddcb98f6c9
RDX: 0000000000000004 RSI: 00002000000000c0 RDI: 0000000000000005
RBP: 00007fddcba11f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fddcbbe6038 R14: 00007fddcbbe5fa0 R15: 00007fff67645d88
 </TASK>
OCFS2: ERROR (device loop8): int ocfs2_validate_gd_self(struct super_block *, struct buffer_head *, int): Group descriptor #2304 has bad signature 
On-disk corruption discovered. Please run fsck.ocfs2 once the filesystem is unmounted.
OCFS2: File system is now read-only.
(syz.8.3866,23524,1):ocfs2_search_chain:1785 ERROR: status = -30
(syz.8.3866,23524,1):ocfs2_search_chain:1871 ERROR: status = -30
(syz.8.3866,23524,1):ocfs2_claim_suballoc_bits:1940 ERROR: status = -30
(syz.8.3866,23524,1):ocfs2_claim_suballoc_bits:1983 ERROR: status = -30
(syz.8.3866,23524,1):__ocfs2_claim_clusters:2355 ERROR: status = -30
(syz.8.3866,23524,1):__ocfs2_claim_clusters:2363 ERROR: status = -30
(syz.8.3866,23524,1):ocfs2_local_alloc_new_window:1203 ERROR: status = -30
(syz.8.3866,23524,1):ocfs2_local_alloc_new_window:1228 ERROR: status = -30
(syz.8.3866,23524,1):ocfs2_local_alloc_slide_window:1302 ERROR: status = -30
(syz.8.3866,23524,1):ocfs2_local_alloc_slide_window:1321 ERROR: status = -30
(syz.8.3866,23524,1):ocfs2_reserve_local_alloc_bits:671 ERROR: status = -30
(syz.8.3866,23524,1):ocfs2_reserve_local_alloc_bits:709 ERROR: status = -30
(syz.8.3866,23524,1):ocfs2_reserve_clusters_with_limit:1166 ERROR: status = -30
(syz.8.3866,23524,1):ocfs2_reserve_clusters_with_limit:1215 ERROR: status = -30
(syz.8.3866,23524,1):ocfs2_convert_inline_data_to_extents:7081 ERROR: status = -30
(syz.8.3866,23524,1):ocfs2_extend_file:1086 ERROR: status = -30
(syz.8.3866,23524,1):ocfs2_setattr:1216 ERROR: status = -30

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/11/14 02:25 linux-6.6.y 0a805b6ea8cd 07e030de .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan possible deadlock in ocfs2_write_begin_nolock
* Struck through repros no longer work on HEAD.