======================================================
WARNING: possible circular locking dependency detected
6.16.0-syzkaller-11895-gcca7a0aae895 #0 Not tainted
------------------------------------------------------
syz.4.5065/18880 is trying to acquire lock:
ffff8881102d2ce0 (&mm->mmap_lock){++++}-{4:4}, at: __might_fault+0xb0/0x130

but task is already holding lock:
ffff8880306b31e0 (&ocfs2_file_ip_alloc_sem_key){++++}-{4:4}
, at: ocfs2_fiemap+0x2b0/0xc90

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #2 (&ocfs2_file_ip_alloc_sem_key){++++}-{4:4}:
       lock_acquire+0x120/0x360
       down_write+0x96/0x1f0
       ocfs2_page_mkwrite+0x2ff/0xc40
       do_page_mkwrite+0x14d/0x310
       do_wp_page+0x268d/0x5800
       __handle_mm_fault+0x1033/0x5440
       handle_mm_fault+0x40a/0x8e0
       do_user_addr_fault+0x764/0x1390
       exc_page_fault+0x76/0xf0
       asm_exc_page_fault+0x26/0x30

-> #1 (sb_pagefaults#4){.+.+}-{0:0}:
       lock_acquire+0x120/0x360
       ocfs2_page_mkwrite+0x1da/0xc40
       do_page_mkwrite+0x14d/0x310
       do_wp_page+0x268d/0x5800
       __handle_mm_fault+0x1033/0x5440
       handle_mm_fault+0x40a/0x8e0
       do_user_addr_fault+0x764/0x1390
       exc_page_fault+0x76/0xf0
       asm_exc_page_fault+0x26/0x30

-> #0 (&mm->mmap_lock){++++}-{4:4}:
       validate_chain+0xb9b/0x2140
       __lock_acquire+0xab9/0xd20
       lock_acquire+0x120/0x360
       __might_fault+0xcc/0x130
       _copy_to_user+0x2c/0xb0
       fiemap_fill_next_extent+0x1c0/0x390
       ocfs2_fiemap+0x9dc/0xc90
       do_vfs_ioctl+0x1173/0x1430
       __se_sys_ioctl+0x82/0x170
       do_syscall_64+0xfa/0x3b0
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

other info that might help us debug this:

Chain exists of:
  &mm->mmap_lock --> sb_pagefaults#4 --> &ocfs2_file_ip_alloc_sem_key

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  rlock(&ocfs2_file_ip_alloc_sem_key);
                               lock(sb_pagefaults#4);
                               lock(&ocfs2_file_ip_alloc_sem_key);
  rlock(&mm->mmap_lock);

 *** DEADLOCK ***

1 lock held by syz.4.5065/18880:
 #0: ffff8880306b31e0 (&ocfs2_file_ip_alloc_sem_key){++++}-{4:4}, at: ocfs2_fiemap+0x2b0/0xc90

stack backtrace:
CPU: 0 UID: 0 PID: 18880 Comm: syz.4.5065 Not tainted 6.16.0-syzkaller-11895-gcca7a0aae895 #0 PREEMPT(full) 
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+0x189/0x250
 print_circular_bug+0x2ee/0x310
 check_noncircular+0x134/0x160
 validate_chain+0xb9b/0x2140
 __lock_acquire+0xab9/0xd20
 lock_acquire+0x120/0x360
 __might_fault+0xcc/0x130
 _copy_to_user+0x2c/0xb0
 fiemap_fill_next_extent+0x1c0/0x390
 ocfs2_fiemap+0x9dc/0xc90
 do_vfs_ioctl+0x1173/0x1430
 __se_sys_ioctl+0x82/0x170
 do_syscall_64+0xfa/0x3b0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f514738ebe9
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:00007f514816c038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f51475b5fa0 RCX: 00007f514738ebe9
RDX: 0000200000000040 RSI: 00000000c020660b RDI: 0000000000000004
RBP: 00007f5147411e19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f51475b6038 R14: 00007f51475b5fa0 R15: 00007ffcea185268
 </TASK>
