======================================================
WARNING: possible circular locking dependency detected
6.4.0-rc1-syzkaller-00071-g105131df9c3b #0 Not tainted
------------------------------------------------------
syz-executor.1/2871 is trying to acquire lock:
ffff88814c6520e0 (&type->s_umount_key#31){++++}-{3:3}, at: __do_sys_quotactl_fd fs/quota/quota.c:999 [inline]
ffff88814c6520e0 (&type->s_umount_key#31){++++}-{3:3}, at: __se_sys_quotactl_fd+0x2fb/0x440 fs/quota/quota.c:972

but task is already holding lock:
ffff88814c652460 (sb_writers#4){.+.+}-{0:0}, at: mnt_want_write+0x3f/0x90 fs/namespace.c:394

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (sb_writers#4){.+.+}-{0:0}:
       lock_acquire+0x1e3/0x520 kernel/locking/lockdep.c:5691
       percpu_down_read include/linux/percpu-rwsem.h:51 [inline]
       __sb_start_write include/linux/fs.h:1494 [inline]
       sb_start_write include/linux/fs.h:1569 [inline]
       write_mmp_block+0xe5/0x930 fs/ext4/mmp.c:50
       ext4_multi_mount_protect+0x35d/0x9f0 fs/ext4/mmp.c:347
       __ext4_remount fs/ext4/super.c:6578 [inline]
       ext4_reconfigure+0x29a8/0x3280 fs/ext4/super.c:6677
       reconfigure_super+0x3c9/0x7c0 fs/super.c:956
       vfs_fsconfig_locked fs/fsopen.c:254 [inline]
       __do_sys_fsconfig fs/fsopen.c:439 [inline]
       __se_sys_fsconfig+0xa29/0xf70 fs/fsopen.c:314
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x63/0xcd

-> #0 (&type->s_umount_key#31){++++}-{3:3}:
       check_prev_add kernel/locking/lockdep.c:3108 [inline]
       check_prevs_add kernel/locking/lockdep.c:3227 [inline]
       validate_chain+0x166b/0x58e0 kernel/locking/lockdep.c:3842
       __lock_acquire+0x1295/0x2000 kernel/locking/lockdep.c:5074
       lock_acquire+0x1e3/0x520 kernel/locking/lockdep.c:5691
       down_read+0x3d/0x50 kernel/locking/rwsem.c:1520
       __do_sys_quotactl_fd fs/quota/quota.c:999 [inline]
       __se_sys_quotactl_fd+0x2fb/0x440 fs/quota/quota.c:972
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x63/0xcd

other info that might help us debug this:

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  rlock(sb_writers#4);
                               lock(&type->s_umount_key#31);
                               lock(sb_writers#4);
  rlock(&type->s_umount_key#31);

 *** DEADLOCK ***

1 lock held by syz-executor.1/2871:
 #0: ffff88814c652460 (sb_writers#4){.+.+}-{0:0}, at: mnt_want_write+0x3f/0x90 fs/namespace.c:394

stack backtrace:
CPU: 0 PID: 2871 Comm: syz-executor.1 Not tainted 6.4.0-rc1-syzkaller-00071-g105131df9c3b #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/14/2023
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x1e7/0x2d0 lib/dump_stack.c:106
 check_noncircular+0x2fe/0x3b0 kernel/locking/lockdep.c:2188
 check_prev_add kernel/locking/lockdep.c:3108 [inline]
 check_prevs_add kernel/locking/lockdep.c:3227 [inline]
 validate_chain+0x166b/0x58e0 kernel/locking/lockdep.c:3842
 __lock_acquire+0x1295/0x2000 kernel/locking/lockdep.c:5074
 lock_acquire+0x1e3/0x520 kernel/locking/lockdep.c:5691
 down_read+0x3d/0x50 kernel/locking/rwsem.c:1520
 __do_sys_quotactl_fd fs/quota/quota.c:999 [inline]
 __se_sys_quotactl_fd+0x2fb/0x440 fs/quota/quota.c:972
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7fab8368c169
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 f1 19 00 00 90 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 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fab84337168 EFLAGS: 00000246 ORIG_RAX: 00000000000001bb
RAX: ffffffffffffffda RBX: 00007fab837abf80 RCX: 00007fab8368c169
RDX: 0000000000000000 RSI: ffffffff80000602 RDI: 0000000000000003
RBP: 00007fab836e7ca1 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000020000340 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fff6b50cfdf R14: 00007fab84337300 R15: 0000000000022000
 </TASK>