======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.2.9519/10039 is trying to acquire lock:
ffffffff8e883040 (fs_reclaim){+.+.}-{0:0}, at: __kmalloc_cache_noprof+0x40/0x660

but task is already holding lock:
ffff88810f924418 (&hugetlbfs_i_mmap_rwsem_key){+.+.}-{4:4}, at: unmap_vmas+0x331/0x6a0

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #8 (&hugetlbfs_i_mmap_rwsem_key){+.+.}-{4:4}:
       down_write+0x96/0x200
       mmap_region+0x1c83/0x2240
       do_mmap+0xc39/0x10c0
       vm_mmap_pgoff+0x2c9/0x4f0
       ksys_mmap_pgoff+0x586/0x760
       do_syscall_64+0x14d/0xf80
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #7 (&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+0x36be/0x3c50
       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+0x14d/0xf80
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #6 (sk_lock-AF_INET6){+.+.}-{0:0}:
       lock_sock_nested+0x48/0x100
       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+0x80f/0x9b0
       netlink_sendmsg+0x813/0xb40
       ____sys_sendmsg+0x972/0x9f0
       ___sys_sendmsg+0x2a5/0x360
       __x64_sys_sendmsg+0x1bd/0x2a0
       do_syscall_64+0x14d/0xf80
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #5 (&nsock->tx_lock){+.+.}-{4:4}:
       __mutex_lock+0x19f/0x1300
       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+0x2f4/0xa70
       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+0xa5/0xa40
       bdev_disk_changed+0x7ba/0x1550
       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+0x14d/0xf80
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #4 (&cmd->lock){+.+.}-{4:4}:
       __mutex_lock+0x19f/0x1300
       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+0x2f4/0xa70
       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+0xa5/0xa40
       bdev_disk_changed+0x7ba/0x1550
       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+0x14d/0xf80
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #3 (set->srcu){.+.+}-{0:0}:
       __synchronize_srcu+0xca/0x3e0
       elevator_switch+0x1e8/0x7a0
       elevator_change+0x2cc/0x450
       elevator_set_default+0x36c/0x430
       blk_register_queue+0x366/0x430
       __add_disk+0x677/0xd50
       add_disk_fwnode+0xfb/0x480
       nbd_dev_add+0x72c/0xb50
       nbd_init+0x168/0x1f0
       do_one_initcall+0x250/0x8d0
       do_initcall_level+0x104/0x190
       do_initcalls+0x59/0xa0
       kernel_init_freeable+0x2a6/0x3e0
       kernel_init+0x1d/0x1d0
       ret_from_fork+0x51e/0xb90
       ret_from_fork_asm+0x1a/0x30

-> #2 (&q->elevator_lock){+.+.}-{4:4}:
       __mutex_lock+0x19f/0x1300
       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+0x80f/0x9b0
       netlink_sendmsg+0x813/0xb40
       ____sys_sendmsg+0x972/0x9f0
       ___sys_sendmsg+0x2a5/0x360
       __x64_sys_sendmsg+0x1bd/0x2a0
       do_syscall_64+0x14d/0xf80
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #1 (&q->q_usage_counter(io)#50){++++}-{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+0x250/0x8d0
       do_initcall_level+0x104/0x190
       do_initcalls+0x59/0xa0
       kernel_init_freeable+0x2a6/0x3e0
       kernel_init+0x1d/0x1d0
       ret_from_fork+0x51e/0xb90
       ret_from_fork_asm+0x1a/0x30

-> #0 (fs_reclaim){+.+.}-{0:0}:
       __lock_acquire+0x15a5/0x2cf0
       lock_acquire+0xf0/0x2e0
       fs_reclaim_acquire+0x71/0x100
       __kmalloc_cache_noprof+0x40/0x660
       allocate_file_region_entries+0x1ef/0x5b0
       __vma_reservation_common+0x6fb/0x8f0
       __unmap_hugepage_range+0x1348/0x1710
       unmap_vmas+0x5a2/0x6a0
       exit_mmap+0x280/0xa10
       __mmput+0x118/0x430
       exit_mm+0x168/0x220
       do_exit+0x6a2/0x23c0
       do_group_exit+0x21b/0x2d0
       __x64_sys_exit_group+0x3f/0x40
       x64_sys_call+0x221a/0x2240
       do_syscall_64+0x14d/0xf80
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

other info that might help us debug this:

Chain exists of:
  fs_reclaim --> &mm->mmap_lock --> &hugetlbfs_i_mmap_rwsem_key

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&hugetlbfs_i_mmap_rwsem_key);
                               lock(&mm->mmap_lock);
                               lock(&hugetlbfs_i_mmap_rwsem_key);
  lock(fs_reclaim);

 *** DEADLOCK ***

3 locks held by syz.2.9519/10039:
 #0: ffff888115491bc0 (&mm->mmap_lock){++++}-{4:4}, at: exit_mmap+0x194/0xa10
 #1: ffff88801bafdce8 (&resv_map->rw_sema){++++}-{4:4}, at: __hugetlb_zap_begin+0x317/0x3a0
 #2: ffff88810f924418 (&hugetlbfs_i_mmap_rwsem_key){+.+.}-{4:4}, at: unmap_vmas+0x331/0x6a0

stack backtrace:
CPU: 0 UID: 0 PID: 10039 Comm: syz.2.9519 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+0xf0/0x2e0
 fs_reclaim_acquire+0x71/0x100
 __kmalloc_cache_noprof+0x40/0x660
 allocate_file_region_entries+0x1ef/0x5b0
 __vma_reservation_common+0x6fb/0x8f0
 __unmap_hugepage_range+0x1348/0x1710
 unmap_vmas+0x5a2/0x6a0
 exit_mmap+0x280/0xa10
 __mmput+0x118/0x430
 exit_mm+0x168/0x220
 do_exit+0x6a2/0x23c0
 do_group_exit+0x21b/0x2d0
 __x64_sys_exit_group+0x3f/0x40
 x64_sys_call+0x221a/0x2240
 do_syscall_64+0x14d/0xf80
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f2ce359c799
Code: Unable to access opcode bytes at 0x7f2ce359c76f.
RSP: 002b:00007ffe52c7bad8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f2ce359c799
RDX: 0000000000000064 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007ffe52c7bb3c R08: 0000000000000000 R09: 00000000000927c0
R10: 00007f2ce3816128 R11: 0000000000000246 R12: 0000000000000c69
R13: 00000000000927c0 R14: 00000000000a8e1d R15: 00007ffe52c7bb90
 </TASK>
