======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.1.8482/25393 is trying to acquire lock:
ffff8881036e4638 (&hugetlb_fault_mutex_table[i]){+.+.}-{4:4}, at: hugetlb_fault+0x3d0/0x12c0

but task is already holding lock:
ffff8881729ec078 (&mm->mmap_lock){++++}-{4:4}, at: __gup_longterm_locked+0xc3b/0x15c0

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+0x210/0x1fb0
       ip_generic_getfrag+0x149/0x2d0
       __ip6_append_data+0x3aef/0x4080
       ip6_append_data+0x108/0x270
       rawv6_sendmsg+0x1298/0x18c0
       ____sys_sendmsg+0x853/0xa20
       ___sys_sendmsg+0x2a5/0x360
       __x64_sys_sendmsg+0x1bd/0x2a0
       do_syscall_64+0x174/0x580
       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+0x2cb/0x550
       recv_work+0x1cef/0x1e10
       process_scheduled_works+0xa8e/0x14e0
       worker_thread+0xa47/0xfb0
       kthread+0x388/0x470
       ret_from_fork+0x514/0xb70
       ret_from_fork_asm+0x1a/0x30

-> #6 (&nsock->tx_lock){+.+.}-{4:4}:
       __mutex_lock+0x19d/0x1590
       nbd_queue_rq+0x373/0x1150
       blk_mq_dispatch_rq_list+0x499/0x1990
       __blk_mq_sched_dispatch_requests+0xd36/0x1580
       blk_mq_sched_dispatch_requests+0xd7/0x190
       blk_mq_run_hw_queue+0x348/0x4f0
       blk_mq_dispatch_list+0xd11/0xe10
       blk_mq_flush_plug_list+0x45f/0x540
       __blk_flush_plug+0x3ed/0x4d0
       __submit_bio+0x465/0x560
       submit_bio_noacct_nocheck+0x2f4/0xa40
       block_read_full_folio+0x581/0x810
       filemap_read_folio+0x12c/0x3a0
       do_read_cache_folio+0x354/0x590
       read_part_sector+0xb6/0x2b0
       adfspart_check_ICS+0xb1/0x960
       bdev_disk_changed+0x82b/0x1780
       blkdev_get_whole+0x372/0x510
       bdev_open+0x324/0xd70
       blkdev_open+0x461/0x600
       do_dentry_open+0x816/0x1380
       vfs_open+0x3b/0x340
       path_openat+0x2e44/0x3830
       do_file_open+0x23e/0x4a0
       do_sys_openat2+0x115/0x200
       __x64_sys_openat+0x138/0x170
       do_syscall_64+0x174/0x580
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #5 (&cmd->lock){+.+.}-{4:4}:
       __mutex_lock+0x19d/0x1590
       nbd_queue_rq+0xc1/0x1150
       blk_mq_dispatch_rq_list+0x499/0x1990
       __blk_mq_sched_dispatch_requests+0xd36/0x1580
       blk_mq_sched_dispatch_requests+0xd7/0x190
       blk_mq_run_hw_queue+0x348/0x4f0
       blk_mq_dispatch_list+0xd11/0xe10
       blk_mq_flush_plug_list+0x45f/0x540
       __blk_flush_plug+0x3ed/0x4d0
       __submit_bio+0x465/0x560
       submit_bio_noacct_nocheck+0x2f4/0xa40
       block_read_full_folio+0x581/0x810
       filemap_read_folio+0x12c/0x3a0
       do_read_cache_folio+0x354/0x590
       read_part_sector+0xb6/0x2b0
       adfspart_check_ICS+0xb1/0x960
       bdev_disk_changed+0x82b/0x1780
       blkdev_get_whole+0x372/0x510
       bdev_open+0x324/0xd70
       blkdev_open+0x461/0x600
       do_dentry_open+0x816/0x1380
       vfs_open+0x3b/0x340
       path_openat+0x2e44/0x3830
       do_file_open+0x23e/0x4a0
       do_sys_openat2+0x115/0x200
       __x64_sys_openat+0x138/0x170
       do_syscall_64+0x174/0x580
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #4 (set->srcu){.+.+}-{0:0}:
       __synchronize_srcu+0xc9/0x2f0
       elevator_switch+0x1e8/0x7b0
       elevator_change+0x2fa/0x480
       elevator_set_default+0x375/0x440
       blk_register_queue+0x3f3/0x4e0
       __add_disk+0x6cb/0xe30
       add_disk_fwnode+0xfb/0x4b0
       nbd_dev_add+0x733/0xb60
       nbd_init+0x15f/0x1e0
       do_one_initcall+0x250/0x870
       do_initcall_level+0x10a/0x1a0
       do_initcalls+0x59/0xa0
       kernel_init_freeable+0x29d/0x3e0
       kernel_init+0x1d/0x1d0
       ret_from_fork+0x514/0xb70
       ret_from_fork_asm+0x1a/0x30

-> #3 (&q->elevator_lock){+.+.}-{4:4}:
       __mutex_lock+0x19d/0x1590
       elevator_change+0x1af/0x480
       elevator_set_none+0xb5/0x140
       blk_mq_update_nr_hw_queues+0x5ef/0x19f0
       nbd_start_device+0x189/0xb30
       nbd_genl_connect+0x1597/0x1c10
       genl_family_rcv_msg_doit+0x233/0x340
       genl_rcv_msg+0x614/0x7a0
       netlink_rcv_skb+0x226/0x4a0
       genl_rcv+0x28/0x40
       netlink_unicast+0x7bb/0x940
       netlink_sendmsg+0x813/0xb40
       ____sys_sendmsg+0x9b9/0xa20
       ___sys_sendmsg+0x2a5/0x360
       __x64_sys_sendmsg+0x1bd/0x2a0
       do_syscall_64+0x174/0x580
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #2 (&q->q_usage_counter(io)#51){++++}-{0:0}:
       blk_alloc_queue+0x544/0x690
       __blk_mq_alloc_disk+0x194/0x390
       nbd_dev_add+0x494/0xb60
       nbd_init+0x15f/0x1e0
       do_one_initcall+0x250/0x870
       do_initcall_level+0x10a/0x1a0
       do_initcalls+0x59/0xa0
       kernel_init_freeable+0x29d/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+0xc3/0x4e0
       __vmf_anon_prepare+0xe1/0x1b0
       hugetlb_no_page+0x421/0x1fc0
       hugetlb_fault+0x570/0x12c0
       handle_mm_fault+0x1f42/0x3080
       __get_user_pages+0x1678/0x2720
       populate_vma_page_range+0x2be/0x3c0
       __mm_populate+0x25f/0x390
       vm_mmap_pgoff+0x353/0x4e0
       ksys_mmap_pgoff+0x57d/0x760
       do_syscall_64+0x174/0x580
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #0 (&hugetlb_fault_mutex_table[i]){+.+.}-{4:4}:
       __lock_acquire+0x1520/0x2cd0
       lock_acquire+0x106/0x350
       __mutex_lock+0x19d/0x1590
       hugetlb_fault+0x3d0/0x12c0
       handle_mm_fault+0x1f42/0x3080
       __get_user_pages+0x1678/0x2720
       __gup_longterm_locked+0xd52/0x15c0
       gup_fast_fallback+0x1d82/0x20d0
       iov_iter_extract_pages+0x369/0x5f0
       extract_iter_to_sg+0xee0/0x25f0
       hash_sendmsg+0x4fd/0x1060
       ____sys_sendmsg+0x9b9/0xa20
       ___sys_sendmsg+0x2a5/0x360
       __sys_sendmmsg+0x27c/0x4e0
       __x64_sys_sendmmsg+0xa0/0xc0
       do_syscall_64+0x174/0x580
       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 ***

2 locks held by syz.1.8482/25393:
 #0: ffff88811dac7260 (sk_lock-AF_ALG){+.+.}-{0:0}, at: hash_sendmsg+0xcf/0x1060
 #1: ffff8881729ec078 (&mm->mmap_lock){++++}-{4:4}, at: __gup_longterm_locked+0xc3b/0x15c0

stack backtrace:
CPU: 0 UID: 0 PID: 25393 Comm: syz.1.8482 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+0x1520/0x2cd0
 lock_acquire+0x106/0x350
 __mutex_lock+0x19d/0x1590
 hugetlb_fault+0x3d0/0x12c0
 handle_mm_fault+0x1f42/0x3080
 __get_user_pages+0x1678/0x2720
 __gup_longterm_locked+0xd52/0x15c0
 gup_fast_fallback+0x1d82/0x20d0
 iov_iter_extract_pages+0x369/0x5f0
 extract_iter_to_sg+0xee0/0x25f0
 hash_sendmsg+0x4fd/0x1060
 ____sys_sendmsg+0x9b9/0xa20
 ___sys_sendmsg+0x2a5/0x360
 __sys_sendmmsg+0x27c/0x4e0
 __x64_sys_sendmmsg+0xa0/0xc0
 do_syscall_64+0x174/0x580
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f939779ce59
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:00007f93985f9028 EFLAGS: 00000246 ORIG_RAX: 0000000000000133
RAX: ffffffffffffffda RBX: 00007f9397a15fa0 RCX: 00007f939779ce59
RDX: 0000000000000001 RSI: 0000200000000640 RDI: 0000000000000005
RBP: 00007f9397832e6f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f9397a16038 R14: 00007f9397a15fa0 R15: 00007fffbe7f6dd8
 </TASK>
