syzbot

======================================================
WARNING: possible circular locking dependency detected
5.15.147-syzkaller #0 Not tainted
------------------------------------------------------
syz-executor.0/4260 is trying to acquire lock:
ffff0001147c02e0 (&type->i_mutex_dir_key#8){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:787 [inline]
ffff0001147c02e0 (&type->i_mutex_dir_key#8){+.+.}-{3:3}, at: chmod_common+0x17c/0x418 fs/open.c:576

but task is already holding lock:
ffff0000c1c64460 (sb_writers#13){.+.+}-{0:0}, at: mnt_want_write+0x44/0x9c fs/namespace.c:377

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #2 (sb_writers#13){.+.+}-{0:0}:
       percpu_down_read include/linux/percpu-rwsem.h:51 [inline]
       __sb_start_write include/linux/fs.h:1785 [inline]
       sb_start_write+0xf0/0x3ac include/linux/fs.h:1855
       mnt_want_write_file+0x64/0x1e8 fs/namespace.c:421
       reiserfs_ioctl+0x188/0x4b8 fs/reiserfs/ioctl.c:103
       vfs_ioctl fs/ioctl.c:51 [inline]
       __do_sys_ioctl fs/ioctl.c:874 [inline]
       __se_sys_ioctl fs/ioctl.c:860 [inline]
       __arm64_sys_ioctl+0x14c/0x1c8 fs/ioctl.c:860
       __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
       invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:52
       el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142
       do_el0_svc+0x58/0x14c arch/arm64/kernel/syscall.c:181
       el0_svc+0x7c/0x1f0 arch/arm64/kernel/entry-common.c:608
       el0t_64_sync_handler+0x84/0xe4 arch/arm64/kernel/entry-common.c:626
       el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584

-> #1 (&sbi->lock){+.+.}-{3:3}:
       __mutex_lock_common+0x194/0x2154 kernel/locking/mutex.c:596
       __mutex_lock kernel/locking/mutex.c:729 [inline]
       mutex_lock_nested+0xa4/0xf8 kernel/locking/mutex.c:743
       reiserfs_write_lock+0x7c/0xe8 fs/reiserfs/lock.c:27
       reiserfs_lookup+0x130/0x3c4 fs/reiserfs/namei.c:364
       __lookup_slow+0x250/0x388 fs/namei.c:1663
       lookup_one_len+0x178/0x28c fs/namei.c:2718
       reiserfs_lookup_privroot+0x8c/0x204 fs/reiserfs/xattr.c:980
       reiserfs_fill_super+0x1aec/0x1e8c fs/reiserfs/super.c:2178
       mount_bdev+0x274/0x370 fs/super.c:1387
       get_super_block+0x44/0x58 fs/reiserfs/super.c:2608
       legacy_get_tree+0xd4/0x16c fs/fs_context.c:611
       vfs_get_tree+0x90/0x274 fs/super.c:1517
       do_new_mount+0x25c/0x8c4 fs/namespace.c:2994
       path_mount+0x594/0x101c fs/namespace.c:3324
       do_mount fs/namespace.c:3337 [inline]
       __do_sys_mount fs/namespace.c:3545 [inline]
       __se_sys_mount fs/namespace.c:3522 [inline]
       __arm64_sys_mount+0x510/0x5e0 fs/namespace.c:3522
       __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
       invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:52
       el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142
       do_el0_svc+0x58/0x14c arch/arm64/kernel/syscall.c:181
       el0_svc+0x7c/0x1f0 arch/arm64/kernel/entry-common.c:608
       el0t_64_sync_handler+0x84/0xe4 arch/arm64/kernel/entry-common.c:626
       el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584

-> #0 (&type->i_mutex_dir_key#8){+.+.}-{3:3}:
       check_prev_add kernel/locking/lockdep.c:3053 [inline]
       check_prevs_add kernel/locking/lockdep.c:3172 [inline]
       validate_chain kernel/locking/lockdep.c:3788 [inline]
       __lock_acquire+0x32d4/0x7638 kernel/locking/lockdep.c:5012
       lock_acquire+0x240/0x77c kernel/locking/lockdep.c:5623
       down_write+0x110/0x260 kernel/locking/rwsem.c:1541
       inode_lock include/linux/fs.h:787 [inline]
       chmod_common+0x17c/0x418 fs/open.c:576
       vfs_fchmod fs/open.c:598 [inline]
       __do_sys_fchmod fs/open.c:607 [inline]
       __se_sys_fchmod fs/open.c:601 [inline]
       __arm64_sys_fchmod+0xe0/0x150 fs/open.c:601
       __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
       invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:52
       el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142
       do_el0_svc+0x58/0x14c arch/arm64/kernel/syscall.c:181
       el0_svc+0x7c/0x1f0 arch/arm64/kernel/entry-common.c:608
       el0t_64_sync_handler+0x84/0xe4 arch/arm64/kernel/entry-common.c:626
       el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584

other info that might help us debug this:

Chain exists of:
  &type->i_mutex_dir_key#8 --> &sbi->lock --> sb_writers#13

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(sb_writers#13);
                               lock(&sbi->lock);
                               lock(sb_writers#13);
  lock(&type->i_mutex_dir_key#8);

 *** DEADLOCK ***

1 lock held by syz-executor.0/4260:
 #0: ffff0000c1c64460 (sb_writers#13){.+.+}-{0:0}, at: mnt_want_write+0x44/0x9c fs/namespace.c:377

stack backtrace:
CPU: 1 PID: 4260 Comm: syz-executor.0 Not tainted 5.15.147-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/17/2023
Call trace:
 dump_backtrace+0x0/0x530 arch/arm64/kernel/stacktrace.c:152
 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:216
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x108/0x170 lib/dump_stack.c:106
 dump_stack+0x1c/0x58 lib/dump_stack.c:113
 print_circular_bug+0x150/0x1b8 kernel/locking/lockdep.c:2011
 check_noncircular+0x2cc/0x378 kernel/locking/lockdep.c:2133
 check_prev_add kernel/locking/lockdep.c:3053 [inline]
 check_prevs_add kernel/locking/lockdep.c:3172 [inline]
 validate_chain kernel/locking/lockdep.c:3788 [inline]
 __lock_acquire+0x32d4/0x7638 kernel/locking/lockdep.c:5012
 lock_acquire+0x240/0x77c kernel/locking/lockdep.c:5623
 down_write+0x110/0x260 kernel/locking/rwsem.c:1541
 inode_lock include/linux/fs.h:787 [inline]
 chmod_common+0x17c/0x418 fs/open.c:576
 vfs_fchmod fs/open.c:598 [inline]
 __do_sys_fchmod fs/open.c:607 [inline]
 __se_sys_fchmod fs/open.c:601 [inline]
 __arm64_sys_fchmod+0xe0/0x150 fs/open.c:601
 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
 invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:52
 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142
 do_el0_svc+0x58/0x14c arch/arm64/kernel/syscall.c:181
 el0_svc+0x7c/0x1f0 arch/arm64/kernel/entry-common.c:608
 el0t_64_sync_handler+0x84/0xe4 arch/arm64/kernel/entry-common.c:626
 el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584