======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.0.16285/27486 is trying to acquire lock:
ffff888162aa0390 (&hugetlb_fault_mutex_table[i]){+.+.}-{4:4}, at: hugetlb_fault+0x3d8/0x1510

but task is already holding lock:
ffff888239d86538 (&mm->mmap_lock){++++}-{4:4}, at: lock_mm_and_find_vma+0x36/0x340

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #8 (&mm->mmap_lock){++++}-{4:4}:
       __might_fault+0xcb/0x130
       _copy_from_user+0x28/0xb0
       csum_and_copy_from_iter_full+0x1e7/0x1f00
       ip_generic_getfrag+0x149/0x2d0
       __ip6_append_data+0x39cd/0x3f60
       ip6_append_data+0x10f/0x280
       rawv6_sendmsg+0x12d3/0x18e0
       ____sys_sendmsg+0x80a/0x9f0
       ___sys_sendmsg+0x2a5/0x360
       __x64_sys_sendmsg+0x1bd/0x2a0
       do_syscall_64+0x15f/0xf80
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #7 (sk_lock-AF_INET6){+.+.}-{0:0}:
       lock_sock_nested+0x41/0x100
       inet_shutdown+0x6a/0x390
       nbd_mark_nsock_dead+0x2e9/0x560
       sock_shutdown+0x15e/0x260
       nbd_clear_sock+0x24/0x170
       nbd_config_put+0x2dd/0x580
       nbd_genl_connect+0x19d5/0x1cf0
       genl_family_rcv_msg_doit+0x22a/0x330
       genl_rcv_msg+0x61c/0x7a0
       netlink_rcv_skb+0x232/0x4b0
       genl_rcv+0x28/0x40
       netlink_unicast+0x75c/0x8e0
       netlink_sendmsg+0x813/0xb40
       ____sys_sendmsg+0x972/0x9f0
       ___sys_sendmsg+0x2a5/0x360
       __x64_sys_sendmsg+0x1bd/0x2a0
       do_syscall_64+0x15f/0xf80
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #6 (&nsock->tx_lock){+.+.}-{4:4}:
       __mutex_lock+0x1a3/0x1550
       nbd_queue_rq+0x37b/0x1100
       blk_mq_dispatch_rq_list+0xa70/0x1910
       __blk_mq_sched_dispatch_requests+0xdcc/0x1600
       blk_mq_sched_dispatch_requests+0xd7/0x190
       blk_mq_run_hw_queue+0x348/0x4f0
       blk_mq_dispatch_list+0xd16/0xe10
       blk_mq_flush_plug_list+0x48d/0x570
       __blk_flush_plug+0x3ed/0x4d0
       __submit_bio+0x28d/0x580
       submit_bio_noacct_nocheck+0x2f4/0xa40
       block_read_full_folio+0x599/0x830
       filemap_read_folio+0x137/0x3b0
       do_read_cache_folio+0x358/0x590
       read_part_sector+0xb6/0x2b0
       adfspart_check_ICS+0xb1/0x960
       bdev_disk_changed+0x817/0x1770
       blkdev_get_whole+0x380/0x510
       bdev_open+0x31e/0xd30
       blkdev_open+0x470/0x610
       do_dentry_open+0x785/0x14e0
       vfs_open+0x3b/0x340
       path_openat+0x2e08/0x3860
       do_file_open+0x23e/0x4a0
       do_sys_openat2+0x113/0x200
       __x64_sys_openat+0x138/0x170
       do_syscall_64+0x15f/0xf80
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #5 (&cmd->lock){+.+.}-{4:4}:
       __mutex_lock+0x1a3/0x1550
       nbd_queue_rq+0xc6/0x1100
       blk_mq_dispatch_rq_list+0xa70/0x1910
       __blk_mq_sched_dispatch_requests+0xdcc/0x1600
       blk_mq_sched_dispatch_requests+0xd7/0x190
       blk_mq_run_hw_queue+0x348/0x4f0
       blk_mq_dispatch_list+0xd16/0xe10
       blk_mq_flush_plug_list+0x48d/0x570
       __blk_flush_plug+0x3ed/0x4d0
       __submit_bio+0x28d/0x580
       submit_bio_noacct_nocheck+0x2f4/0xa40
       block_read_full_folio+0x599/0x830
       filemap_read_folio+0x137/0x3b0
       do_read_cache_folio+0x358/0x590
       read_part_sector+0xb6/0x2b0
       adfspart_check_ICS+0xb1/0x960
       bdev_disk_changed+0x817/0x1770
       blkdev_get_whole+0x380/0x510
       bdev_open+0x31e/0xd30
       blkdev_open+0x470/0x610
       do_dentry_open+0x785/0x14e0
       vfs_open+0x3b/0x340
       path_openat+0x2e08/0x3860
       do_file_open+0x23e/0x4a0
       do_sys_openat2+0x113/0x200
       __x64_sys_openat+0x138/0x170
       do_syscall_64+0x15f/0xf80
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #4 (set->srcu){.+.+}-{0:0}:
       __synchronize_srcu+0xca/0x300
       elevator_switch+0x1e8/0x7a0
       elevator_change+0x2cc/0x450
       elevator_set_default+0x36c/0x430
       blk_register_queue+0x3e9/0x4e0
       __add_disk+0x677/0xd50
       add_disk_fwnode+0xfb/0x480
       nbd_dev_add+0x72c/0xb50
       nbd_init+0x168/0x1f0
       do_one_initcall+0x250/0x870
       do_initcall_level+0x104/0x190
       do_initcalls+0x59/0xa0
       kernel_init_freeable+0x2a6/0x3e0
       kernel_init+0x1d/0x1d0
       ret_from_fork+0x514/0xb70
       ret_from_fork_asm+0x1a/0x30

-> #3 (&q->elevator_lock){+.+.}-{4:4}:
       __mutex_lock+0x1a3/0x1550
       elevator_change+0x1b3/0x450
       elevator_set_none+0xb5/0x140
       blk_mq_update_nr_hw_queues+0x5e7/0x1a60
       nbd_start_device+0x17f/0xb10
       nbd_genl_connect+0x165b/0x1cf0
       genl_family_rcv_msg_doit+0x22a/0x330
       genl_rcv_msg+0x61c/0x7a0
       netlink_rcv_skb+0x232/0x4b0
       genl_rcv+0x28/0x40
       netlink_unicast+0x75c/0x8e0
       netlink_sendmsg+0x813/0xb40
       ____sys_sendmsg+0x972/0x9f0
       ___sys_sendmsg+0x2a5/0x360
       __x64_sys_sendmsg+0x1bd/0x2a0
       do_syscall_64+0x15f/0xf80
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #2 (&q->q_usage_counter(io)#49){++++}-{0:0}:
       blk_alloc_queue+0x546/0x680
       __blk_mq_alloc_disk+0x197/0x390
       nbd_dev_add+0x499/0xb50
       nbd_init+0x168/0x1f0
       do_one_initcall+0x250/0x870
       do_initcall_level+0x104/0x190
       do_initcalls+0x59/0xa0
       kernel_init_freeable+0x2a6/0x3e0
       kernel_init+0x1d/0x1d0
       ret_from_fork+0x514/0xb70
       ret_from_fork_asm+0x1a/0x30

-> #1 (fs_reclaim){+.+.}-{0:0}:
       fs_reclaim_acquire+0x71/0x100
       kmem_cache_alloc_noprof+0x40/0x650
       __anon_vma_prepare+0xcb/0x4a0
       __vmf_anon_prepare+0xe1/0x1b0
       hugetlb_no_page+0x399/0x2100
       hugetlb_fault+0x747/0x1510
       handle_mm_fault+0x2007/0x3170
       do_user_addr_fault+0x75b/0x1340
       exc_page_fault+0x6a/0xc0
       asm_exc_page_fault+0x26/0x30
       rep_movs_alternative+0x30/0x90
       _copy_from_user+0x7a/0xb0
       ___sys_recvmsg+0x175/0x590
       do_recvmmsg+0x334/0x800
       __x64_sys_recvmmsg+0x198/0x250
       do_syscall_64+0x15f/0xf80
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #0 (&hugetlb_fault_mutex_table[i]){+.+.}-{4:4}:
       __lock_acquire+0x15a5/0x2cf0
       lock_acquire+0x106/0x350
       __mutex_lock+0x1a3/0x1550
       hugetlb_fault+0x3d8/0x1510
       handle_mm_fault+0x2007/0x3170
       do_user_addr_fault+0x75b/0x1340
       exc_page_fault+0x6a/0xc0
       asm_exc_page_fault+0x26/0x30
       fault_in_readable+0x8e/0x130
       fault_in_iov_iter_readable+0x1b4/0x2f0
       generic_perform_write+0x7af/0x8f0
       shmem_file_write_iter+0xf8/0x120
       vfs_write+0x61d/0xb90
       ksys_write+0x150/0x270
       do_syscall_64+0x15f/0xf80
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

other info that might help us debug this:

Chain exists of:
  &hugetlb_fault_mutex_table[i] --> sk_lock-AF_INET6 --> &mm->mmap_lock

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  rlock(&mm->mmap_lock);
                               lock(sk_lock-AF_INET6);
                               lock(&mm->mmap_lock);
  lock(&hugetlb_fault_mutex_table[i]);

 *** DEADLOCK ***

4 locks held by syz.0.16285/27486:
 #0: ffff8881a88294f0 (&f->f_pos_lock){+.+.}-{4:4}, at: fdget_pos+0x246/0x320
 #1: ffff88816ae3e410 (sb_writers#5){.+.+}-{0:0}, at: vfs_write+0x227/0xb90
 #2: ffff888168588280 (&sb->s_type->i_mutex_key#15){+.+.}-{4:4}, at: shmem_file_write_iter+0x7f/0x120
 #3: ffff888239d86538 (&mm->mmap_lock){++++}-{4:4}, at: lock_mm_and_find_vma+0x36/0x340

stack backtrace:
CPU: 1 UID: 0 PID: 27486 Comm: syz.0.16285 Not tainted syzkaller #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+0xe8/0x150
 print_circular_bug+0x2e1/0x300
 check_noncircular+0x12e/0x150
 __lock_acquire+0x15a5/0x2cf0
 lock_acquire+0x106/0x350
 __mutex_lock+0x1a3/0x1550
 hugetlb_fault+0x3d8/0x1510
 handle_mm_fault+0x2007/0x3170
 do_user_addr_fault+0x75b/0x1340
 exc_page_fault+0x6a/0xc0
 asm_exc_page_fault+0x26/0x30
RIP: 0010:fault_in_readable+0x8e/0x130
Code: a9 00 00 00 0f 1f 00 0f ae e8 4d 85 f6 40 0f 95 c5 4c 89 ff 4c 89 f6 e8 90 f0 b0 ff 4d 39 f7 0f 97 c0 40 84 c5 74 43 4d 89 f5 <41> 8a 45 00 88 44 24 07 49 81 e5 00 f0 ff ff 4d 8d a5 00 10 00 00
RSP: 0018:ffffc90009897aa8 EFLAGS: 00010202
RAX: ffffffff8214d101 RBX: 0000000000001000 RCX: ffff88811355bb00
RDX: 0000000000000002 RSI: 0000200000000080 RDI: 0000200000001080
RBP: dffffc0000000001 R08: ffff88811355bb00 R09: 0000000000000002
R10: 0000000000000001 R11: 0000000000000002 R12: 00007ffffffff000
R13: 0000200000000080 R14: 0000200000000080 R15: 0000200000001080
 fault_in_iov_iter_readable+0x1b4/0x2f0
 generic_perform_write+0x7af/0x8f0
 shmem_file_write_iter+0xf8/0x120
 vfs_write+0x61d/0xb90
 ksys_write+0x150/0x270
 do_syscall_64+0x15f/0xf80
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f72c239cdd9
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:00007f72c3333028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f72c2615fa0 RCX: 00007f72c239cdd9
RDX: 0000000000010448 RSI: 0000200000000080 RDI: 0000000000000004
RBP: 00007f72c2432d69 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f72c2616038 R14: 00007f72c2615fa0 R15: 00007ffe78d421b8
 </TASK>
