======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Tainted: G             L     
------------------------------------------------------
syz.7.4043/16460 is trying to acquire lock:
ffff8881b85c9cb8 (&ovl_i_mutex_dir_key[depth]#2){++++}-{4:4}, at: lookup_slow+0x46/0x70

but task is already holding lock:
ffff88816a2bc080 (&of->mutex){+.+.}-{4:4}, at: kernfs_fop_write_iter+0x1d8/0x540

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #4 (&of->mutex){+.+.}-{4:4}:
       __mutex_lock+0x19d/0x1550
       kernfs_seq_start+0x5d/0x420
       seq_read_iter+0x37e/0xca0
       copy_splice_read+0x5ff/0xaa0
       splice_direct_to_actor+0x48b/0xcb0
       do_splice_direct+0x195/0x290
       do_sendfile+0x52e/0x7c0
       __se_sys_sendfile64+0x144/0x1a0
       do_syscall_64+0x166/0x520
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #3 (&p->lock){+.+.}-{4:4}:
       __mutex_lock+0x19d/0x1550
       seq_read_iter+0xa4/0xca0
       copy_splice_read+0x5ff/0xaa0
       splice_file_to_pipe+0x444/0x6b0
       do_sendfile+0x4d4/0x7c0
       __se_sys_sendfile64+0x144/0x1a0
       do_syscall_64+0x166/0x520
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #2 (&pipe->mutex){+.+.}-{4:4}:
       __mutex_lock+0x19d/0x1550
       iter_file_splice_write+0x20a/0x1240
       do_splice+0xf14/0x1970
       __se_sys_splice+0x353/0x490
       do_syscall_64+0x166/0x520
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #1 (sb_writers#5){.+.+}-{0:0}:
       sb_start_write+0x4d/0x1d0
       mnt_want_write+0x41/0x90
       ovl_create_object+0x10d/0x3b0
       lookup_open+0xc0d/0x1a40
       path_openat+0x677/0x1d60
       do_file_open+0x23e/0x4a0
       do_sys_openat2+0x115/0x200
       __x64_sys_openat+0x138/0x170
       do_syscall_64+0x166/0x520
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #0 (&ovl_i_mutex_dir_key[depth]#2){++++}-{4:4}:
       __lock_acquire+0x1520/0x2cf0
       lock_acquire+0x106/0x350
       down_read+0x4a/0x330
       lookup_slow+0x46/0x70
       path_lookupat+0x3f5/0x8c0
       filename_lookup+0x265/0x5d0
       kern_path+0x3d/0x150
       lookup_bdev+0xc8/0x2b0
       resume_store+0x16f/0x4f0
       kernfs_fop_write_iter+0x3a4/0x540
       vfs_write+0x612/0xba0
       ksys_write+0x150/0x270
       do_syscall_64+0x166/0x520
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

other info that might help us debug this:

Chain exists of:
  &ovl_i_mutex_dir_key[depth]#2 --> &p->lock --> &of->mutex

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&of->mutex);
                               lock(&p->lock);
                               lock(&of->mutex);
  rlock(&ovl_i_mutex_dir_key[depth]#2);

 *** DEADLOCK ***

locks held by syz.7.4043/16460: 4, last CPU#1:
 #0: ffff8881bbff24f0 (&f->f_pos_lock){+.+.}-{4:4}, at: fdget_pos+0x246/0x320
 #1: ffff88816a138460 (sb_writers#7){.+.+}-{0:0}, at: vfs_write+0x22b/0xba0
 #2: ffff88816a2bc080 (&of->mutex){+.+.}-{4:4}, at: kernfs_fop_write_iter+0x1d8/0x540
 #3: ffff888161a88968 (kn->active#70){.+.+}-{0:0}, at: kernfs_fop_write_iter+0x22b/0x540

stack backtrace:
CPU: 1 UID: 60929 PID: 16460 Comm: syz.7.4043 Tainted: G             L      syzkaller #0 PREEMPT(lazy) 
Tainted: [L]=SOFTLOCKUP
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150
 print_circular_bug+0x2e1/0x300
 check_noncircular+0x12e/0x150
 __lock_acquire+0x1520/0x2cf0
 lock_acquire+0x106/0x350
 down_read+0x4a/0x330
 lookup_slow+0x46/0x70
 path_lookupat+0x3f5/0x8c0
 filename_lookup+0x265/0x5d0
 kern_path+0x3d/0x150
 lookup_bdev+0xc8/0x2b0
 resume_store+0x16f/0x4f0
 kernfs_fop_write_iter+0x3a4/0x540
 vfs_write+0x612/0xba0
 ksys_write+0x150/0x270
 do_syscall_64+0x166/0x520
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fa66fd9e159
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:00007fa670bb0028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007fa670026090 RCX: 00007fa66fd9e159
RDX: 00000000ffffff30 RSI: 00002000000001c0 RDI: 000000000000000a
RBP: 00007fa66fe3506b R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fa670026128 R14: 00007fa670026090 R15: 00007fffa21099a8
 </TASK>
PM: Image not found (code -16)
