ldm_validate_partition_table(): Disk read failed.
Dev nbd2: unable to read RDB block 0
 nbd2: unable to read partition table
======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Tainted: G             L     
------------------------------------------------------
udevd/6520 is trying to acquire lock:
ffff88810ae72ef0 (&q->q_usage_counter(io)#51){++++}-{0:0}, at: __submit_bio+0x1c0/0x580

but task is already holding lock:
ffff888107b49500 (mapping.invalidate_lock){++++}-{4:4}, at: filemap_get_pages+0x991/0x1ef0

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #7 (mapping.invalidate_lock){++++}-{4:4}:
       down_read+0x47/0x2e0
       page_cache_ra_order+0x37a/0xe80
       do_sync_mmap_readahead+0x6ad/0x8e0
       filemap_fault+0x703/0x1300
       __do_fault+0x138/0x2a0
       do_pte_missing+0x601/0x33f0
       handle_mm_fault+0x1bd7/0x3170
       __get_user_pages+0x1683/0x2720
       faultin_page_range+0x44a/0x8c0
       madvise_do_behavior+0x2e5/0x540
       do_madvise+0x1fa/0x2e0
       __x64_sys_madvise+0xa6/0xc0
       do_syscall_64+0x15f/0xf80
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #6 (&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

-> #5 (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

-> #4 (&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+0x7b7/0x830
       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+0x3dd/0x4a0
       do_sys_openat2+0x113/0x200
       __x64_sys_openat+0x138/0x170
       do_syscall_64+0x15f/0xf80
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #3 (&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+0x7b7/0x830
       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+0x3dd/0x4a0
       do_sys_openat2+0x113/0x200
       __x64_sys_openat+0x138/0x170
       do_syscall_64+0x15f/0xf80
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #2 (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

-> #1 (&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

-> #0 (&q->q_usage_counter(io)#51){++++}-{0:0}:
       __lock_acquire+0x15a5/0x2cf0
       lock_acquire+0x106/0x350
       blk_mq_submit_bio+0x6de/0x28e0
       __submit_bio+0x1c0/0x580
       submit_bio_noacct_nocheck+0x2f4/0xa40
       block_read_full_folio+0x7b7/0x830
       filemap_read_folio+0x137/0x3b0
       filemap_get_pages+0x1744/0x1ef0
       filemap_read+0x447/0x1230
       blkdev_read_iter+0x30a/0x440
       vfs_read+0x582/0xa70
       ksys_read+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:
  &q->q_usage_counter(io)#51 --> &mm->mmap_lock --> mapping.invalidate_lock

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  rlock(mapping.invalidate_lock);
                               lock(&mm->mmap_lock);
                               lock(mapping.invalidate_lock);
  rlock(&q->q_usage_counter(io)#51);

 *** DEADLOCK ***

2 locks held by udevd/6520:
 #0: ffff888107b49368 (&sb->s_type->i_mutex_key#10){++++}-{4:4}, at: blkdev_read_iter+0x2f8/0x440
 #1: ffff888107b49500 (mapping.invalidate_lock){++++}-{4:4}, at: filemap_get_pages+0x991/0x1ef0

stack backtrace:
CPU: 1 UID: 0 PID: 6520 Comm: udevd Tainted: G             L      syzkaller #0 PREEMPT(full) 
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+0x15a5/0x2cf0
 lock_acquire+0x106/0x350
 blk_mq_submit_bio+0x6de/0x28e0
 __submit_bio+0x1c0/0x580
 submit_bio_noacct_nocheck+0x2f4/0xa40
 block_read_full_folio+0x7b7/0x830
 filemap_read_folio+0x137/0x3b0
 filemap_get_pages+0x1744/0x1ef0
 filemap_read+0x447/0x1230
 blkdev_read_iter+0x30a/0x440
 vfs_read+0x582/0xa70
 ksys_read+0x150/0x270
 do_syscall_64+0x15f/0xf80
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f6c7b716b6a
Code: 00 3d 00 00 41 00 75 0d 50 48 8d 3d 2d 08 0a 00 e8 ea 7d 01 00 31 c0 e9 07 ff ff ff 64 8b 04 25 18 00 00 00 85 c0 75 1b 0f 05 <48> 3d 00 f0 ff ff 76 6c 48 8b 15 8f a2 0d 00 f7 d8 64 89 02 48 83
RSP: 002b:00007ffd8b445ba8 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f6c7b716b6a
RDX: 0000000000000400 RSI: 000055d9e0714838 RDI: 0000000000000009
RBP: 0000000000000400 R08: 000055d9e0714810 R09: 0000000000000008
R10: 0000000000000051 R11: 0000000000000246 R12: 000055d9e0714810
R13: 000055d9e0714828 R14: 000055d9e0487ee8 R15: 000055d9e0487e90
 </TASK>
