RAX: ffffffffffffffda RBX: 0000000000000002 RCX: 00007eff30d38dd9
RDX: 0000000000000000 RSI: 000000000000ab03 RDI: 0000000000000007
RBP: 00007ffe8409d460 R08: 0000000000000002 R09: 00007eff30003431
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000008
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
BUG: unable to handle kernel NULL pointer dereference at 0000000000000120
IP: set_bit arch/x86/include/asm/bitops.h:81 [inline]
IP: cpumask_set_cpu include/linux/cpumask.h:283 [inline]
IP: blk_mq_map_swqueue+0x253/0x990 block/blk-mq.c:2171
PGD a9c95067 P4D a9c95067 PUD a9f35067 PMD 0 
Oops: 0002 [#1] PREEMPT SMP KASAN
Modules linked in:
CPU: 1 PID: 7968 Comm: syz-executor246 Not tainted 4.14.285-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff88809a1f0340 task.stack: ffff8880915a0000
RIP: 0010:set_bit arch/x86/include/asm/bitops.h:81 [inline]
RIP: 0010:cpumask_set_cpu include/linux/cpumask.h:283 [inline]
RIP: 0010:blk_mq_map_swqueue+0x253/0x990 block/blk-mq.c:2171
RSP: 0018:ffff8880915a7a80 EFLAGS: 00010297
RAX: ffff88809a1f0340 RBX: ffff8880ae99b0b0 RCX: 1ffff11015d1bfd1
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffffff88cc7d68
RBP: 0000000000000001 R08: ffff8880ae8dfe80 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000001
R13: ffff8882386b0280 R14: 0000000000000000 R15: dffffc0000000000
FS:  0000555556b04300(0000) GS:ffff8880ba500000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000120 CR3: 00000000a56b1000 CR4: 00000000003406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 blk_mq_queue_reinit block/blk-mq.c:2514 [inline]
 __blk_mq_update_nr_hw_queues block/blk-mq.c:2752 [inline]
 blk_mq_update_nr_hw_queues+0x246/0x3e0 block/blk-mq.c:2762
 nbd_start_device+0x1d7/0xca0 drivers/block/nbd.c:1201
 nbd_start_device_ioctl drivers/block/nbd.c:1252 [inline]
 __nbd_ioctl drivers/block/nbd.c:1334 [inline]
 nbd_ioctl+0x3c4/0xac0 drivers/block/nbd.c:1374
 __blkdev_driver_ioctl block/ioctl.c:297 [inline]
 blkdev_ioctl+0x540/0x1830 block/ioctl.c:594
 block_ioctl+0xd9/0x120 fs/block_dev.c:1893
 vfs_ioctl fs/ioctl.c:46 [inline]
 file_ioctl fs/ioctl.c:500 [inline]
 do_vfs_ioctl+0x75a/0xff0 fs/ioctl.c:684
 SYSC_ioctl fs/ioctl.c:701 [inline]
 SyS_ioctl+0x7f/0xb0 fs/ioctl.c:692
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x46/0xbb
RIP: 0033:0x7eff30d38dd9
RSP: 002b:00007ffe8409d458 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000002 RCX: 00007eff30d38dd9
RDX: 0000000000000000 RSI: 000000000000ab03 RDI: 0000000000000007
RBP: 00007ffe8409d460 R08: 0000000000000002 R09: 00007eff30003431
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000008
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
Code: 4d 8d 34 c8 4c 89 f1 48 c1 e9 03 42 80 3c 39 00 0f 85 37 05 00 00 83 fd 07 4d 8b 36 0f 87 42 04 00 00 48 89 04 24 e8 6d 3d 4a fe <f0> 4d 0f ab a6 20 01 00 00 49 8d be 78 01 00 00 48 8b 04 24 48 
RIP: set_bit arch/x86/include/asm/bitops.h:81 [inline] RSP: ffff8880915a7a80
RIP: cpumask_set_cpu include/linux/cpumask.h:283 [inline] RSP: ffff8880915a7a80
RIP: blk_mq_map_swqueue+0x253/0x990 block/blk-mq.c:2171 RSP: ffff8880915a7a80
CR2: 0000000000000120
---[ end trace 076375593567f551 ]---
----------------
Code disassembly (best guess):
   0:	4d 8d 34 c8          	lea    (%r8,%rcx,8),%r14
   4:	4c 89 f1             	mov    %r14,%rcx
   7:	48 c1 e9 03          	shr    $0x3,%rcx
   b:	42 80 3c 39 00       	cmpb   $0x0,(%rcx,%r15,1)
  10:	0f 85 37 05 00 00    	jne    0x54d
  16:	83 fd 07             	cmp    $0x7,%ebp
  19:	4d 8b 36             	mov    (%r14),%r14
  1c:	0f 87 42 04 00 00    	ja     0x464
  22:	48 89 04 24          	mov    %rax,(%rsp)
  26:	e8 6d 3d 4a fe       	callq  0xfe4a3d98
* 2b:	f0 4d 0f ab a6 20 01 	lock bts %r12,0x120(%r14) <-- trapping instruction
  32:	00 00
  34:	49 8d be 78 01 00 00 	lea    0x178(%r14),%rdi
  3b:	48 8b 04 24          	mov    (%rsp),%rax
  3f:	48                   	rex.W