RAX: ffffffffffffffda RBX: 00007f21d55f76d4 RCX: 000000000045b349
RDX: 0000000000000000 RSI: 000000000000ab03 RDI: 0000000000000005
RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000008
R13: 00000000000003fd R14: 00000000004c549d R15: 0000000000000008
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+0x25e/0x9c0 block/blk-mq.c:2171
PGD a907a067 P4D a907a067 PUD 82df2067 PMD 0 
Oops: 0002 [#1] PREEMPT SMP KASAN
Modules linked in:
CPU: 1 PID: 2721 Comm: syz-executor.4 Not tainted 4.14.168-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff888050e5c6c0 task.stack: ffff88804ccb0000
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+0x25e/0x9c0 block/blk-mq.c:2171
RSP: 0018:ffff88804ccb7a48 EFLAGS: 00010246
RAX: 0000000000040000 RBX: 0000000000000001 RCX: ffffc90005b3c000
RDX: 0000000000000000 RSI: ffffffff82ffbb7a RDI: ffff8880a43cf748
RBP: ffff88804ccb7ac0 R08: 0000000000000000 R09: 0000000000000000
R10: dffffc0000000000 R11: ffff88804ccb78e0 R12: 0000000000000001
R13: ffff8880a43dbd00 R14: dffffc0000000000 R15: ffff8880a3c8f030
FS:  00007f21d55f7700(0000) GS:ffff8880aed00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000120 CR3: 000000008aa91000 CR4: 00000000001426e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 blk_mq_queue_reinit block/blk-mq.c:2512 [inline]
 __blk_mq_update_nr_hw_queues block/blk-mq.c:2746 [inline]
 blk_mq_update_nr_hw_queues+0x21c/0x3a0 block/blk-mq.c:2756
 nbd_start_device+0x1d7/0xc50 drivers/block/nbd.c:1187
 nbd_start_device_ioctl drivers/block/nbd.c:1228 [inline]
 __nbd_ioctl drivers/block/nbd.c:1310 [inline]
 nbd_ioctl+0x43d/0xb30 drivers/block/nbd.c:1350
 __blkdev_driver_ioctl block/ioctl.c:297 [inline]
 blkdev_ioctl+0x95f/0x1850 block/ioctl.c:594
 block_ioctl+0xde/0x120 fs/block_dev.c:1881
 vfs_ioctl fs/ioctl.c:46 [inline]
 file_ioctl fs/ioctl.c:500 [inline]
 do_vfs_ioctl+0x7ae/0x1060 fs/ioctl.c:684
 SYSC_ioctl fs/ioctl.c:701 [inline]
 SyS_ioctl+0x8f/0xc0 fs/ioctl.c:692
 do_syscall_64+0x1e8/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x45b349
RSP: 002b:00007f21d55f6c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f21d55f76d4 RCX: 000000000045b349
RDX: 0000000000000000 RSI: 000000000000ab03 RDI: 0000000000000005
RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000008
R13: 00000000000003fd R14: 00000000004c549d R15: 0000000000000008
Code: ea 03 42 80 3c 32 00 0f 85 94 06 00 00 41 83 fc 3f 48 8b 17 0f 87 4b 04 00 00 48 89 55 c8 48 89 45 d0 e8 26 59 5d fe 48 8b 55 c8 <f0> 48 0f ab 9a 20 01 00 00 48 8d ba 78 01 00 00 48 8b 45 d0 48 
RIP: set_bit arch/x86/include/asm/bitops.h:81 [inline] RSP: ffff88804ccb7a48
RIP: cpumask_set_cpu include/linux/cpumask.h:283 [inline] RSP: ffff88804ccb7a48
RIP: blk_mq_map_swqueue+0x25e/0x9c0 block/blk-mq.c:2171 RSP: ffff88804ccb7a48
CR2: 0000000000000120
---[ end trace 8476beb611425dc8 ]---