syzbot


possible deadlock in ocfs2_write_begin_nolock

Status: upstream: reported on 2025/06/24 08:23
Reported-by: syzbot+956197518a1aedc45c0e@syzkaller.appspotmail.com
First crash: 15d, last: 15d
Similar bugs (3)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream possible deadlock in ocfs2_write_begin_nolock ocfs2 4 C 635 2d22h 300d 0/29 upstream: reported C repro on 2024/09/12 09:35
linux-6.1 possible deadlock in ocfs2_write_begin_nolock 4 120 33d 270d 0/3 upstream: reported on 2024/10/11 23:44
linux-5.15 possible deadlock in ocfs2_write_begin_nolock 4 83 8d19h 255d 0/3 upstream: reported on 2024/10/27 04:30

Sample crash report:
ocfs2: Mounting device (7,1) on (node local, slot 0) with ordered data mode.
======================================================
WARNING: possible circular locking dependency detected
6.6.94-syzkaller #0 Not tainted
------------------------------------------------------
syz.1.1342/10248 is trying to acquire lock:
ffff888026356608 (sb_internal#3){.+.+}-{0:0}, at: ocfs2_write_begin_inline fs/ocfs2/aops.c:1481 [inline]
ffff888026356608 (sb_internal#3){.+.+}-{0:0}, at: ocfs2_try_to_write_inline_data fs/ocfs2/aops.c:1584 [inline]
ffff888026356608 (sb_internal#3){.+.+}-{0:0}, at: ocfs2_write_begin_nolock+0x1c91/0x4190 fs/ocfs2/aops.c:1670

but task is already holding lock:
ffff88805f5f3120 (&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]
       __do_sys_fsetxattr fs/xattr.c:711 [inline]
       __se_sys_fsetxattr+0x450/0x4b0 fs/xattr.c:687
       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:3488 [inline]
       open_last_lookups fs/namei.c:3556 [inline]
       path_openat+0x1277/0x3190 fs/namei.c:3786
       do_filp_open+0x1c5/0x3d0 fs/namei.c:3816
       do_sys_openat2+0x12c/0x1c0 fs/open.c:1419
       do_sys_open fs/open.c:1434 [inline]
       __do_sys_open fs/open.c:1442 [inline]
       __se_sys_open fs/open.c:1438 [inline]
       __x64_sys_open+0x11f/0x140 fs/open.c:1438
       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:1883
       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:1250
       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+0xb1/0x140 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:1883
       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:1250
       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+0xb1/0x140 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#3){.+.+}-{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#3 --> &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#3);

 *** DEADLOCK ***

4 locks held by syz.1.1342/10248:
 #0: ffff88806ca705c8 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0x2a3/0x330 fs/file.c:1042
 #1: ffff888026356418 (sb_writers#14){.+.+}-{0:0}, at: vfs_write+0x20e/0x940 fs/read_write.c:580
 #2: ffff88805f5f3498 (&sb->s_type->i_mutex_key#25){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:804 [inline]
 #2: ffff88805f5f3498 (&sb->s_type->i_mutex_key#25){+.+.}-{3:3}, at: ocfs2_file_write_iter+0x40b/0x1d00 fs/ocfs2/file.c:2398
 #3: ffff88805f5f3120 (&ocfs2_file_ip_alloc_sem_key){++++}-{3:3}, at: ocfs2_write_begin+0x199/0x310 fs/ocfs2/aops.c:1902

stack backtrace:
CPU: 1 PID: 10248 Comm: syz.1.1342 Not tainted 6.6.94-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
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: 0033:0x7fd51818e929
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:00007fd518fa0038 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007fd5183b5fa0 RCX: 00007fd51818e929
RDX: 00000000000000a0 RSI: 0000200000002440 RDI: 0000000000000004
RBP: 00007fd518210b39 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007fd5183b5fa0 R15: 00007ffd18c145c8
 </TASK>

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/06/24 08:23 linux-6.6.y 6282921b6825 e2f27c35 .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.