bisecting fixing commit since 9a95f25269bd9257ab9fba7bb14355d50b5f39ec
building syzkaller on c8e81ce4c7e3b59e7c83c6fab56c217916f3b3b6
testing commit 9a95f25269bd9257ab9fba7bb14355d50b5f39ec with gcc (GCC) 8.4.1 20210217
kernel signature: aa2a7ebcac15034e38ee039525c9e7da7f1a0fda8b355dd1217e9e0b726fb7ff
run #0: crashed: BUG: unable to handle kernel
run #1: crashed: BUG: unable to handle kernel
run #2: crashed: BUG: unable to handle kernel NULL pointer dereference in blk_mq_map_swqueue
run #3: crashed: BUG: unable to handle kernel NULL pointer dereference in blk_mq_map_swqueue
run #4: crashed: BUG: unable to handle kernel
run #5: crashed: BUG: unable to handle kernel NULL pointer dereference in blk_mq_map_swqueue
run #6: crashed: BUG: unable to handle kernel
run #7: crashed: BUG: unable to handle kernel
run #8: crashed: BUG: unable to handle kernel NULL pointer dereference in blk_mq_map_swqueue
run #9: crashed: BUG: unable to handle kernel
run #10: crashed: BUG: unable to handle kernel
run #11: crashed: BUG: unable to handle kernel
run #12: crashed: BUG: unable to handle kernel
run #13: crashed: BUG: unable to handle kernel
run #14: crashed: BUG: unable to handle kernel NULL pointer dereference in blk_mq_map_swqueue
run #15: crashed: BUG: unable to handle kernel
run #16: crashed: BUG: unable to handle kernel NULL pointer dereference in blk_mq_map_swqueue
run #17: crashed: BUG: unable to handle kernel
run #18: crashed: BUG: unable to handle kernel NULL pointer dereference in blk_mq_map_swqueue
run #19: crashed: BUG: unable to handle kernel NULL pointer dereference in corrupted
testing current HEAD 3242aa3a635c0958671ee1e4b0958dcc7c4e5c79
testing commit 3242aa3a635c0958671ee1e4b0958dcc7c4e5c79 with gcc (GCC) 8.4.1 20210217
kernel signature: f01c61dda87e3ea5984fa9eb3ccc6ebf41404b906b78cb0b343b999cc98364ed
run #0: crashed: BUG: unable to handle kernel
run #1: crashed: BUG: unable to handle kernel
run #2: crashed: BUG: unable to handle kernel
run #3: crashed: BUG: unable to handle kernel
run #4: crashed: BUG: unable to handle kernel NULL pointer dereference in blk_mq_map_swqueue
run #5: crashed: BUG: unable to handle kernel
run #6: crashed: BUG: unable to handle kernel
run #7: crashed: BUG: unable to handle kernel
run #8: crashed: BUG: unable to handle kernel
run #9: crashed: BUG: unable to handle kernel NULL pointer dereference in blk_mq_map_swqueue
revisions tested: 2, total time: 22m45.266094423s (build: 15m8.253244943s, test: 6m16.265329395s)
the crash still happens on HEAD
commit msg: Linux 4.14.222
crash: BUG: unable to handle kernel NULL pointer dereference in blk_mq_map_swqueue
RAX: ffffffffffffffda RBX: 00000000000003fd RCX: 0000000000462c89
RDX: 0000000000000000 RSI: 000000000000ab03 RDI: 0000000000000005
RBP: 0000000000000010 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000052bf00
R13: 00007efd8bd7f6bc R14: 0000000000000008 R15: 0000000000000001
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+0x23a/0xa90 block/blk-mq.c:2171
PGD 1e1482067 P4D 1e1482067 PUD 1d0aee067 PMD 0 
Oops: 0002 [#1] PREEMPT SMP KASAN
Modules linked in:
CPU: 0 PID: 7049 Comm: syz-executor.3 Not tainted 4.14.222-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8881d8146480 task.stack: ffff8881d8b60000
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+0x23a/0xa90 block/blk-mq.c:2171
RSP: 0018:ffff8881d8b679e0 EFLAGS: 00010293
RAX: ffff8881ed3f8b48 RBX: 0000000000000007 RCX: ffffe8ffffd31b80
RDX: 0000000000000001 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffff8881d8b67a58 R08: 0000000000000001 R09: 0000000000000001
R10: ffff8881ed3f8b40 R11: ffff8881ed3f8c00 R12: ffff8881ed3ed0c0
R13: fffffbfff11653ee R14: ffff8881ecc5c480 R15: dffffc0000000000
FS:  00007efd8bd7f700(0000) GS:ffff8881f6600000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000120 CR3: 00000001d8982005 CR4: 00000000001606f0
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:2750 [inline]
 blk_mq_update_nr_hw_queues+0x219/0x390 block/blk-mq.c:2760
 nbd_start_device+0x1b6/0xc50 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+0x1ae/0xad0 drivers/block/nbd.c:1374
 __blkdev_driver_ioctl block/ioctl.c:297 [inline]
 blkdev_ioctl+0x7d2/0x1770 block/ioctl.c:594
 block_ioctl+0xd7/0x130 fs/block_dev.c:1893
 vfs_ioctl fs/ioctl.c:46 [inline]
 file_ioctl fs/ioctl.c:500 [inline]
 do_vfs_ioctl+0x180/0xfb0 fs/ioctl.c:684
 SYSC_ioctl fs/ioctl.c:701 [inline]
 SyS_ioctl+0x74/0x80 fs/ioctl.c:692
 do_syscall_64+0x1c7/0x5b0 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x46/0xbb
RIP: 0033:0x462c89
RSP: 002b:00007efd8bd7f198 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00000000000003fd RCX: 0000000000462c89
RDX: 0000000000000000 RSI: 000000000000ab03 RDI: 0000000000000005
RBP: 0000000000000010 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000052bf00
R13: 00007efd8bd7f6bc R14: 0000000000000008 R15: 0000000000000001
Code: 0f 85 dd 05 00 00 8b 00 49 8d 04 c2 48 89 c6 48 c1 ee 03 42 80 3c 3e 00 0f 85 98 05 00 00 41 83 f8 3f 48 8b 30 0f 87 f3 03 00 00 <f0> 4c 0f ab 8e 20 01 00 00 48 8d be 78 01 00 00 48 89 f8 48 c1 
RIP: set_bit arch/x86/include/asm/bitops.h:81 [inline] RSP: ffff8881d8b679e0
RIP: cpumask_set_cpu include/linux/cpumask.h:283 [inline] RSP: ffff8881d8b679e0
RIP: blk_mq_map_swqueue+0x23a/0xa90 block/blk-mq.c:2171 RSP: ffff8881d8b679e0
CR2: 0000000000000120
batman_adv: The newly added mac address (aa:aa:aa:aa:aa:3e) already exists on: batadv_slave_1
---[ end trace ba9178f5a392f90c ]---