syzbot

REISERFS (device loop0): Using tea hash to sort names
REISERFS (device loop0): Created .reiserfs_priv - reserved for xattr storage.
======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.0.1224/8897 is trying to acquire lock:
ffff8880192a3090 (&sbi->lock){+.+.}-{3:3}, at: reiserfs_write_lock+0x79/0xd0 fs/reiserfs/lock.c:27

but task is already holding lock:
ffff888077671030 (&type->i_mutex_dir_key#22/1){+.+.}-{3:3}, at: inode_lock_nested include/linux/fs.h:839 [inline]
ffff888077671030 (&type->i_mutex_dir_key#22/1){+.+.}-{3:3}, at: filename_create+0x20c/0x480 fs/namei.c:3890

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #2 (&type->i_mutex_dir_key#22/1){+.+.}-{3:3}:
       down_write_nested+0x9e/0x200 kernel/locking/rwsem.c:1689
       inode_lock_nested include/linux/fs.h:839 [inline]
       filename_create+0x20c/0x480 fs/namei.c:3890
       do_symlinkat+0xc5/0x400 fs/namei.c:4500
       __do_sys_symlinkat fs/namei.c:4523 [inline]
       __se_sys_symlinkat fs/namei.c:4520 [inline]
       __x64_sys_symlinkat+0x99/0xb0 fs/namei.c:4520
       do_syscall_x64 arch/x86/entry/common.c:46 [inline]
       do_syscall_64+0x55/0xa0 arch/x86/entry/common.c:76
       entry_SYSCALL_64_after_hwframe+0x68/0xd2

-> #1 (sb_writers#28){.+.+}-{0:0}:
       percpu_down_read include/linux/percpu-rwsem.h:51 [inline]
       __sb_start_write include/linux/fs.h:1633 [inline]
       sb_start_write+0x4d/0x1c0 include/linux/fs.h:1708
       mnt_want_write_file+0x63/0x200 fs/namespace.c:456
       reiserfs_ioctl+0x112/0x2d0 fs/reiserfs/ioctl.c:103
       vfs_ioctl fs/ioctl.c:51 [inline]
       __do_sys_ioctl fs/ioctl.c:871 [inline]
       __se_sys_ioctl+0xfd/0x170 fs/ioctl.c:857
       do_syscall_x64 arch/x86/entry/common.c:46 [inline]
       do_syscall_64+0x55/0xa0 arch/x86/entry/common.c:76
       entry_SYSCALL_64_after_hwframe+0x68/0xd2

-> #0 (&sbi->lock){+.+.}-{3:3}:
       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+0x2df1/0x7d40 kernel/locking/lockdep.c:5137
       lock_acquire+0x19e/0x420 kernel/locking/lockdep.c:5754
       __mutex_lock_common kernel/locking/mutex.c:603 [inline]
       __mutex_lock+0x136/0xcc0 kernel/locking/mutex.c:747
       reiserfs_write_lock+0x79/0xd0 fs/reiserfs/lock.c:27
       reiserfs_lookup+0x183/0x580 fs/reiserfs/namei.c:364
       lookup_one_qstr_excl+0x112/0x250 fs/namei.c:1617
       filename_create+0x23e/0x480 fs/namei.c:3891
       do_symlinkat+0xc5/0x400 fs/namei.c:4500
       __do_sys_symlinkat fs/namei.c:4523 [inline]
       __se_sys_symlinkat fs/namei.c:4520 [inline]
       __x64_sys_symlinkat+0x99/0xb0 fs/namei.c:4520
       do_syscall_x64 arch/x86/entry/common.c:46 [inline]
       do_syscall_64+0x55/0xa0 arch/x86/entry/common.c:76
       entry_SYSCALL_64_after_hwframe+0x68/0xd2

other info that might help us debug this:

Chain exists of:
  &sbi->lock --> sb_writers#28 --> &type->i_mutex_dir_key#22/1

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&type->i_mutex_dir_key#22/1);
                               lock(sb_writers#28);
                               lock(&type->i_mutex_dir_key#22/1);
  lock(&sbi->lock);

 *** DEADLOCK ***

2 locks held by syz.0.1224/8897:
 #0: ffff88807d7a4418 (sb_writers#28){.+.+}-{0:0}, at: mnt_want_write+0x41/0x90 fs/namespace.c:412
 #1: ffff888077671030 (&type->i_mutex_dir_key#22/1){+.+.}-{3:3}, at: inode_lock_nested include/linux/fs.h:839 [inline]
 #1: ffff888077671030 (&type->i_mutex_dir_key#22/1){+.+.}-{3:3}, at: filename_create+0x20c/0x480 fs/namei.c:3890

stack backtrace:
CPU: 0 PID: 8897 Comm: syz.0.1224 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0x18c/0x250 lib/dump_stack.c:106
 check_noncircular+0x2fc/0x400 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+0x2df1/0x7d40 kernel/locking/lockdep.c:5137
 lock_acquire+0x19e/0x420 kernel/locking/lockdep.c:5754
 __mutex_lock_common kernel/locking/mutex.c:603 [inline]
 __mutex_lock+0x136/0xcc0 kernel/locking/mutex.c:747
 reiserfs_write_lock+0x79/0xd0 fs/reiserfs/lock.c:27
 reiserfs_lookup+0x183/0x580 fs/reiserfs/namei.c:364
 lookup_one_qstr_excl+0x112/0x250 fs/namei.c:1617
 filename_create+0x23e/0x480 fs/namei.c:3891
 do_symlinkat+0xc5/0x400 fs/namei.c:4500
 __do_sys_symlinkat fs/namei.c:4523 [inline]
 __se_sys_symlinkat fs/namei.c:4520 [inline]
 __x64_sys_symlinkat+0x99/0xb0 fs/namei.c:4520
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x55/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fdb7359c819
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:00007fdb74428028 EFLAGS: 00000246 ORIG_RAX: 000000000000010a
RAX: ffffffffffffffda RBX: 00007fdb73815fa0 RCX: 00007fdb7359c819
RDX: 00002000000005c0 RSI: ffffffffffffff9c RDI: 0000200000000700
RBP: 00007fdb73632c91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fdb73816038 R14: 00007fdb73815fa0 R15: 00007ffc68724828
 </TASK>