============================================
WARNING: possible recursive locking detected
syzkaller #0 Tainted: G             L      
--------------------------------------------
syz.0.1026/12274 is trying to acquire lock:
ffff888024969368 (&sb->s_type->i_mutex_key#10){++++}-{4:4}, at: inode_lock_shared include/linux/fs.h:1039 [inline]
ffff888024969368 (&sb->s_type->i_mutex_key#10){++++}-{4:4}, at: blkdev_buffered_write+0xd7/0x160 block/fops.c:738

but task is already holding lock:
ffff888024969368 (&sb->s_type->i_mutex_key#10){++++}-{4:4}, at: inode_lock_shared include/linux/fs.h:1039 [inline]
ffff888024969368 (&sb->s_type->i_mutex_key#10){++++}-{4:4}, at: blkdev_write_iter+0x6c5/0x810 block/fops.c:815

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

       CPU0
       ----
  lock(&sb->s_type->i_mutex_key#10);
  lock(&sb->s_type->i_mutex_key#10);

 *** DEADLOCK ***

 May be due to missing lock nesting notation

locks held by syz.0.1026/12274: 1, last CPU#1:
 #0: ffff888024969368 (&sb->s_type->i_mutex_key#10){++++}-{4:4}, at: inode_lock_shared include/linux/fs.h:1039 [inline]
 #0: ffff888024969368 (&sb->s_type->i_mutex_key#10){++++}-{4:4}, at: blkdev_write_iter+0x6c5/0x810 block/fops.c:815

stack backtrace:
CPU: 1 UID: 0 PID: 12274 Comm: syz.0.1026 Tainted: G             L       syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/16/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 print_deadlock_bug+0x27a/0x290 kernel/locking/lockdep.c:3085
 check_deadlock kernel/locking/lockdep.c:3137 [inline]
 validate_chain kernel/locking/lockdep.c:3939 [inline]
 __lock_acquire+0x25db/0x2de0 kernel/locking/lockdep.c:5288
 lock_acquire+0x115/0x350 kernel/locking/lockdep.c:5942
 down_read+0x45/0x320 kernel/locking/rwsem.c:1574
 inode_lock_shared include/linux/fs.h:1039 [inline]
 blkdev_buffered_write+0xd7/0x160 block/fops.c:738
 blkdev_write_iter+0x6d5/0x810 block/fops.c:816
 new_sync_write fs/read_write.c:595 [inline]
 vfs_write+0x612/0xba0 fs/read_write.c:687
 ksys_write+0x150/0x270 fs/read_write.c:1036
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f8dba39e559
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:00007f8dbb18b028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f8dba626090 RCX: 00007f8dba39e559
RDX: 00000000ffffffdb RSI: 0000000000000000 RDI: 0000000000000004
RBP: 00007f8dba435ab8 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f8dba626128 R14: 00007f8dba626090 R15: 00007ffd25ee5f88
 </TASK>