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: 34d, last: 6d06h
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 656 1d15h 319d 0/29 upstream: reported C repro on 2024/09/12 09:35
linux-6.1 possible deadlock in ocfs2_write_begin_nolock 4 128 1d13h 289d 0/3 upstream: reported on 2024/10/11 23:44
linux-5.15 possible deadlock in ocfs2_write_begin_nolock 4 99 3h05m 274d 0/3 upstream: reported on 2024/10/27 04:30

Sample crash report:
ocfs2: Mounting device (7,3) on (node local, slot 0) with ordered data mode.
======================================================
WARNING: possible circular locking dependency detected
6.6.99-syzkaller #0 Not tainted
------------------------------------------------------
syz.3.98/6246 is trying to acquire lock:
ffff88807af8c608 (sb_internal#3){.+.+}-{0:0}, at: ocfs2_write_begin_inline fs/ocfs2/aops.c:1481 [inline]
ffff88807af8c608 (sb_internal#3){.+.+}-{0:0}, at: ocfs2_try_to_write_inline_data fs/ocfs2/aops.c:1584 [inline]
ffff88807af8c608 (sb_internal#3){.+.+}-{0:0}, at: ocfs2_write_begin_nolock+0x1c91/0x4190 fs/ocfs2/aops.c:1670

but task is already holding lock:
ffff888078713f60 (&oi->ip_alloc_sem){++++}-{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 (&oi->ip_alloc_sem){++++}-{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_remove_acl+0x4e3/0x740 fs/posix_acl.c:1243
       removexattr fs/xattr.c:907 [inline]
       path_removexattr+0x23b/0x3f0 fs/xattr.c:929
       __do_sys_removexattr fs/xattr.c:943 [inline]
       __se_sys_removexattr fs/xattr.c:940 [inline]
       __x64_sys_removexattr+0x60/0x70 fs/xattr.c:940
       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_mkdir+0x196/0x410 fs/ocfs2/namei.c:657
       vfs_mkdir+0x296/0x440 fs/namei.c:4113
       do_mkdirat+0x1d4/0x440 fs/namei.c:4136
       __do_sys_mkdirat fs/namei.c:4151 [inline]
       __se_sys_mkdirat fs/namei.c:4149 [inline]
       __x64_sys_mkdirat+0x89/0xa0 fs/namei.c:4149
       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_mknod+0xe47/0x20f0 fs/ocfs2/namei.c:361
       ocfs2_mkdir+0x196/0x410 fs/ocfs2/namei.c:657
       vfs_mkdir+0x296/0x440 fs/namei.c:4113
       do_mkdirat+0x1d4/0x440 fs/namei.c:4136
       __do_sys_mkdirat fs/namei.c:4151 [inline]
       __se_sys_mkdirat fs/namei.c:4149 [inline]
       __x64_sys_mkdirat+0x89/0xa0 fs/namei.c:4149
       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

-> #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_mknod+0xe47/0x20f0 fs/ocfs2/namei.c:361
       ocfs2_mkdir+0x196/0x410 fs/ocfs2/namei.c:657
       vfs_mkdir+0x296/0x440 fs/namei.c:4113
       do_mkdirat+0x1d4/0x440 fs/namei.c:4136
       __do_sys_mkdirat fs/namei.c:4151 [inline]
       __se_sys_mkdirat fs/namei.c:4149 [inline]
       __x64_sys_mkdirat+0x89/0xa0 fs/namei.c:4149
       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

-> #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 --> &oi->ip_alloc_sem

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&oi->ip_alloc_sem);
                               lock(&oi->ip_xattr_sem);
                               lock(&oi->ip_alloc_sem);
  rlock(sb_internal#3);

 *** DEADLOCK ***

4 locks held by syz.3.98/6246:
 #0: ffff888025ec2d48 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0x2a3/0x330 fs/file.c:1042
 #1: ffff88807af8c418 (sb_writers#16){.+.+}-{0:0}, at: vfs_write+0x20e/0x940 fs/read_write.c:580
 #2: ffff8880787142d8 (&sb->s_type->i_mutex_key#22){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:804 [inline]
 #2: ffff8880787142d8 (&sb->s_type->i_mutex_key#22){+.+.}-{3:3}, at: ocfs2_file_write_iter+0x40b/0x1d00 fs/ocfs2/file.c:2398
 #3: ffff888078713f60 (&oi->ip_alloc_sem){++++}-{3:3}, at: ocfs2_write_begin+0x199/0x310 fs/ocfs2/aops.c:1902

stack backtrace:
CPU: 0 PID: 6246 Comm: syz.3.98 Not tainted 6.6.99-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: 0033:0x7fa6b3d8e9a9
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:00007fa6b4bd3038 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007fa6b3fb5fa0 RCX: 00007fa6b3d8e9a9
RDX: 0000000000000020 RSI: 00002000000002c0 RDI: 0000000000000004
RBP: 00007fa6b3e10d69 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007fa6b3fb5fa0 R15: 00007ffe01d455f8
 </TASK>

Crashes (3):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/07/22 13:30 linux-6.6.y d96eb99e2f0e 1555463b .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan possible deadlock in ocfs2_write_begin_nolock
2025/07/22 13:29 linux-6.6.y d96eb99e2f0e 1555463b .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan possible deadlock in ocfs2_write_begin_nolock
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.