BTRFS: device fsid 395ef67a-297e-477c-816d-cd80a5b93e5d devid 1 transid 8 /dev/loop0 (7:0) scanned by syz-executor (3063)
BTRFS info (device loop0): first mount of filesystem 395ef67a-297e-477c-816d-cd80a5b93e5d
BTRFS info (device loop0): using sha256 (sha256-avx2) checksum algorithm
BTRFS info (device loop0): using free-space-tree
============================================
WARNING: possible recursive locking detected
6.9.0-rc5-syzkaller #0 Not tainted
--------------------------------------------
syz-executor/3063 is trying to acquire lock:
ffff888107b4e408 (sb_writers#4){.+.+}-{0:0}, at: ovl_do_copy_up fs/overlayfs/copy_up.c:967 [inline]
ffff888107b4e408 (sb_writers#4){.+.+}-{0:0}, at: ovl_copy_up_one fs/overlayfs/copy_up.c:1168 [inline]
ffff888107b4e408 (sb_writers#4){.+.+}-{0:0}, at: ovl_copy_up_flags+0x4d0/0x19a0 fs/overlayfs/copy_up.c:1223

but task is already holding lock:
ffff888107b4e408 (sb_writers#4){.+.+}-{0:0}, at: mnt_want_write+0x12/0x40 fs/namespace.c:409

other info that might help us debug this:
 Possible unsafe locking scenario:

       CPU0
       ----
  lock(sb_writers#4);
  lock(sb_writers#4);

 *** DEADLOCK ***

 May be due to missing lock nesting notation

3 locks held by syz-executor/3063:
 #0: ffff888109c7f408 (sb_writers#12){.+.+}-{0:0}, at: mnt_want_write+0x12/0x40 fs/namespace.c:409
 #1: ffff888107b4e408 (sb_writers#4){.+.+}-{0:0}, at: mnt_want_write+0x12/0x40 fs/namespace.c:409
 #2: ffff88810bf48518 (&ovl_i_lock_key[depth]){+.+.}-{3:3}, at: ovl_inode_lock_interruptible fs/overlayfs/overlayfs.h:657 [inline]
 #2: ffff88810bf48518 (&ovl_i_lock_key[depth]){+.+.}-{3:3}, at: ovl_copy_up_start+0x23/0xb0 fs/overlayfs/util.c:719

stack backtrace:
CPU: 0 PID: 3063 Comm: syz-executor Not tainted 6.9.0-rc5-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/02/2024
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xa3/0x100 lib/dump_stack.c:114
 check_deadlock kernel/locking/lockdep.c:3062 [inline]
 validate_chain kernel/locking/lockdep.c:3856 [inline]
 __lock_acquire+0x10bf/0x2490 kernel/locking/lockdep.c:5137
 lock_acquire+0xeb/0x270 kernel/locking/lockdep.c:5754
 percpu_down_read include/linux/percpu-rwsem.h:51 [inline]
 __sb_start_write include/linux/fs.h:1664 [inline]
 sb_start_write include/linux/fs.h:1800 [inline]
 ovl_start_write+0x4e/0xf0 fs/overlayfs/util.c:31
 ovl_do_copy_up fs/overlayfs/copy_up.c:967 [inline]
 ovl_copy_up_one fs/overlayfs/copy_up.c:1168 [inline]
 ovl_copy_up_flags+0x4d0/0x19a0 fs/overlayfs/copy_up.c:1223
 ovl_create_tmpfile fs/overlayfs/dir.c:1320 [inline]
 ovl_tmpfile+0xba/0x290 fs/overlayfs/dir.c:1376
 vfs_tmpfile+0xf4/0x190 fs/namei.c:3693
 do_tmpfile+0x70/0x100 fs/namei.c:3756
 path_openat+0xcd7/0xda0 fs/namei.c:3790
 do_filp_open+0xad/0x150 fs/namei.c:3826
 do_sys_openat2+0x7e/0xe0 fs/open.c:1406
 do_sys_open fs/open.c:1421 [inline]
 __do_sys_open fs/open.c:1429 [inline]
 __se_sys_open fs/open.c:1425 [inline]
 __x64_sys_open+0x7a/0xa0 fs/open.c:1425
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xa2/0x1b0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f1c8b47cee9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 e1 20 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 b0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f1c8c1cd0c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000002
RAX: ffffffffffffffda RBX: 00007f1c8b5abf80 RCX: 00007f1c8b47cee9
RDX: 0000000000000000 RSI: 0000000000410202 RDI: 0000000020000040
RBP: 00007f1c8b4c949e R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000006 R14: 00007f1c8b5abf80 R15: 00007ffd3582c6b8
 </TASK>