============================================
WARNING: possible recursive locking detected
6.15.0-rc4-syzkaller-00052-g4f79eaa2ceac #0 Not tainted
--------------------------------------------
syz.0.0/5316 is trying to acquire lock:
ffff88805341dfa8 (&sb->s_type->i_mutex_key#20){++++}-{4:4}, at: inode_lock include/linux/fs.h:867 [inline]
ffff88805341dfa8 (&sb->s_type->i_mutex_key#20){++++}-{4:4}, at: bch2_symlink+0xf2/0x240 fs/bcachefs/fs.c:885

but task is already holding lock:
ffff88805341d078 (&sb->s_type->i_mutex_key#20){++++}-{4:4}, at: inode_lock include/linux/fs.h:867 [inline]
ffff88805341d078 (&sb->s_type->i_mutex_key#20){++++}-{4:4}, at: ovl_copy_up_workdir fs/overlayfs/copy_up.c:782 [inline]
ffff88805341d078 (&sb->s_type->i_mutex_key#20){++++}-{4:4}, at: ovl_do_copy_up fs/overlayfs/copy_up.c:1001 [inline]
ffff88805341d078 (&sb->s_type->i_mutex_key#20){++++}-{4:4}, at: ovl_copy_up_one fs/overlayfs/copy_up.c:1202 [inline]
ffff88805341d078 (&sb->s_type->i_mutex_key#20){++++}-{4:4}, at: ovl_copy_up_flags+0x10ee/0x2fb0 fs/overlayfs/copy_up.c:1257

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

       CPU0
       ----
  lock(&sb->s_type->i_mutex_key#20);
  lock(&sb->s_type->i_mutex_key#20);

 *** DEADLOCK ***

 May be due to missing lock nesting notation

6 locks held by syz.0.0/5316:
 #0: ffff88801c364420 (sb_writers#13){.+.+}-{0:0}, at: mnt_want_write+0x41/0x90 fs/namespace.c:556
 #1: ffff888053419e50 (&ovl_i_mutex_dir_key[depth]/1){+.+.}-{4:4}, at: inode_lock_nested include/linux/fs.h:902 [inline]
 #1: ffff888053419e50 (&ovl_i_mutex_dir_key[depth]/1){+.+.}-{4:4}, at: filename_create+0x1f9/0x470 fs/namei.c:4132
 #2: ffff88805341a418 (&ovl_i_mutex_key[depth]){+.+.}-{4:4}, at: inode_lock include/linux/fs.h:867 [inline]
 #2: ffff88805341a418 (&ovl_i_mutex_key[depth]){+.+.}-{4:4}, at: vfs_link+0x3b4/0x6e0 fs/namei.c:4838
 #3: ffff88805341a7d0 (&ovl_i_lock_key[depth]){+.+.}-{4:4}, at: ovl_inode_lock_interruptible fs/overlayfs/overlayfs.h:649 [inline]
 #3: ffff88805341a7d0 (&ovl_i_lock_key[depth]){+.+.}-{4:4}, at: ovl_copy_up_start+0x56/0x310 fs/overlayfs/util.c:727
 #4: ffff88801ef7c420 (sb_writers#12){.+.+}-{0:0}, at: ovl_copy_up_workdir fs/overlayfs/copy_up.c:781 [inline]
 #4: ffff88801ef7c420 (sb_writers#12){.+.+}-{0:0}, at: ovl_do_copy_up fs/overlayfs/copy_up.c:1001 [inline]
 #4: ffff88801ef7c420 (sb_writers#12){.+.+}-{0:0}, at: ovl_copy_up_one fs/overlayfs/copy_up.c:1202 [inline]
 #4: ffff88801ef7c420 (sb_writers#12){.+.+}-{0:0}, at: ovl_copy_up_flags+0x10df/0x2fb0 fs/overlayfs/copy_up.c:1257
 #5: ffff88805341d078 (&sb->s_type->i_mutex_key#20){++++}-{4:4}, at: inode_lock include/linux/fs.h:867 [inline]
 #5: ffff88805341d078 (&sb->s_type->i_mutex_key#20){++++}-{4:4}, at: ovl_copy_up_workdir fs/overlayfs/copy_up.c:782 [inline]
 #5: ffff88805341d078 (&sb->s_type->i_mutex_key#20){++++}-{4:4}, at: ovl_do_copy_up fs/overlayfs/copy_up.c:1001 [inline]
 #5: ffff88805341d078 (&sb->s_type->i_mutex_key#20){++++}-{4:4}, at: ovl_copy_up_one fs/overlayfs/copy_up.c:1202 [inline]
 #5: ffff88805341d078 (&sb->s_type->i_mutex_key#20){++++}-{4:4}, at: ovl_copy_up_flags+0x10ee/0x2fb0 fs/overlayfs/copy_up.c:1257

stack backtrace:
CPU: 0 UID: 0 PID: 5316 Comm: syz.0.0 Not tainted 6.15.0-rc4-syzkaller-00052-g4f79eaa2ceac #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
 print_deadlock_bug+0x28b/0x2a0 kernel/locking/lockdep.c:3042
 check_deadlock kernel/locking/lockdep.c:3094 [inline]
 validate_chain+0x1a3f/0x2140 kernel/locking/lockdep.c:3896
 __lock_acquire+0xaac/0xd20 kernel/locking/lockdep.c:5235
 lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5866
 down_write+0x96/0x1f0 kernel/locking/rwsem.c:1577
 inode_lock include/linux/fs.h:867 [inline]
 bch2_symlink+0xf2/0x240 fs/bcachefs/fs.c:885
 vfs_symlink+0x140/0x2f0 fs/namei.c:4723
 ovl_do_symlink+0x89/0xd0 fs/overlayfs/overlayfs.h:268
 ovl_create_real+0x228/0x3f0 fs/overlayfs/dir.c:176
 ovl_copy_up_workdir fs/overlayfs/copy_up.c:783 [inline]
 ovl_do_copy_up fs/overlayfs/copy_up.c:1001 [inline]
 ovl_copy_up_one fs/overlayfs/copy_up.c:1202 [inline]
 ovl_copy_up_flags+0x1108/0x2fb0 fs/overlayfs/copy_up.c:1257
 ovl_link+0x85/0x270 fs/overlayfs/dir.c:702
 vfs_link+0x4ea/0x6e0 fs/namei.c:4847
 do_linkat+0x272/0x560 fs/namei.c:4917
 __do_sys_link fs/namei.c:4951 [inline]
 __se_sys_link fs/namei.c:4949 [inline]
 __x64_sys_link+0x82/0x90 fs/namei.c:4949
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xf6/0x210 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f8031f8e969
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:00007f8032e83038 EFLAGS: 00000246 ORIG_RAX: 0000000000000056
RAX: ffffffffffffffda RBX: 00007f80321b6080 RCX: 00007f8031f8e969
RDX: 0000000000000000 RSI: 00002000000001c0 RDI: 0000200000000100
RBP: 00007f8032010ab1 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f80321b6080 R15: 00007ffeb8ddaa58
 </TASK>