bisecting fixing commit since 9a95f25269bd9257ab9fba7bb14355d50b5f39ec building syzkaller on c8e81ce4c7e3b59e7c83c6fab56c217916f3b3b6 testing commit 9a95f25269bd9257ab9fba7bb14355d50b5f39ec with gcc (GCC) 8.4.1 20210217 kernel signature: 4e32dd4d4bb6ec2bdfe1665613e8efd764d68b8875466b09fa013e6b361b3d5d run #0: crashed: BUG: unable to handle kernel NULL pointer dereference in blk_mq_map_swqueue run #1: crashed: BUG: unable to handle kernel NULL pointer dereference in corrupted run #2: crashed: BUG: unable to handle kernel 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 run #6: crashed: BUG: unable to handle kernel NULL pointer dereference in blk_mq_map_swqueue 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 NULL pointer dereference in blk_mq_map_swqueue run #11: crashed: BUG: unable to handle kernel run #12: crashed: BUG: unable to handle kernel NULL pointer dereference in blk_mq_map_swqueue run #13: crashed: BUG: unable to handle kernel NULL pointer dereference in blk_mq_map_swqueue run #14: crashed: BUG: unable to handle kernel NULL pointer dereference in blk_mq_map_swqueue run #15: crashed: BUG: unable to handle kernel NULL pointer dereference in blk_mq_map_swqueue run #16: crashed: BUG: unable to handle kernel NULL pointer dereference in blk_mq_map_swqueue run #17: crashed: BUG: unable to handle kernel NULL pointer dereference in blk_mq_map_swqueue run #18: crashed: BUG: unable to handle kernel run #19: crashed: BUG: unable to handle kernel testing current HEAD cf256fbcbe347b7d0ff58fe2dfa382a156bd3694 testing commit cf256fbcbe347b7d0ff58fe2dfa382a156bd3694 with gcc (GCC) 8.4.1 20210217 kernel signature: e9916e195d0da1935dc46c92d69a6693b15178543abcfd81e2c773c7ee6b6756 run #0: crashed: BUG: unable to handle kernel NULL pointer dereference in blk_mq_map_swqueue run #1: crashed: BUG: unable to handle kernel NULL pointer dereference in blk_mq_map_swqueue run #2: crashed: BUG: unable to handle kernel 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 run #6: crashed: BUG: unable to handle kernel NULL pointer dereference in blk_mq_map_swqueue run #7: crashed: BUG: unable to handle kernel NULL pointer dereference in blk_mq_map_swqueue run #8: crashed: BUG: unable to handle kernel NULL pointer dereference in blk_mq_map_swqueue run #9: crashed: BUG: unable to handle kernel NULL pointer dereference in blk_mq_map_swqueue revisions tested: 2, total time: 27m59.025531148s (build: 20m34.892548229s, test: 6m31.841898525s) the crash still happens on HEAD commit msg: Linux 4.14.231 crash: BUG: unable to handle kernel NULL pointer dereference in blk_mq_map_swqueue R10: 0000000000000000 R11: 0000000000000246 R12: 000000000052bf00 R13: 00007fecc356c6bc R14: 0000000000000008 R15: 0000000000000001 IPv6: ADDRCONF(NETDEV_CHANGE): macvtap0: link becomes ready IPv6: ADDRCONF(NETDEV_CHANGE): macsec0: link becomes ready IPv6: ADDRCONF(NETDEV_CHANGE): batadv_slave_0: link becomes ready BUG: unable to handle kernel NULL pointer dereference at 0000000000000120 IPv6: ADDRCONF(NETDEV_CHANGE): veth0_to_batadv: link becomes ready 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 IPv6: ADDRCONF(NETDEV_CHANGE): veth1_vlan: link becomes ready PGD 1dcd87067 P4D 1dcd87067 PUD 1dcdbe067 PMD 0 Oops: 0002 [#1] PREEMPT SMP KASAN Modules linked in: CPU: 0 PID: 6994 Comm: syz-executor.2 Not tainted 4.14.231-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 task: ffff8881dea16000 task.stack: ffff8881db570000 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:ffff8881db5779e0 EFLAGS: 00010293 IPv6: ADDRCONF(NETDEV_CHANGE): veth0_vlan: link becomes ready IPv6: ADDRCONF(NETDEV_CHANGE): batadv_slave_0: link becomes ready RAX: ffff8881ed33ae88 RBX: 0000000000000007 RCX: ffffe8ffffd31440 RDX: 0000000000000001 RSI: 0000000000000000 RDI: 0000000000000000 RBP: ffff8881db577a58 R08: 0000000000000001 R09: 0000000000000001 R10: ffff8881ed33ae80 R11: ffff8881ed1bcf40 R12: ffff8881ed352340 R13: fffffbfff116589e R14: ffff8881ecc4cff0 R15: dffffc0000000000 FS: 00007fecc356c700(0000) GS:ffff8881f6600000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000120 CR3: 00000001dc8c0006 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 IPv6: ADDRCONF(NETDEV_CHANGE): veth0_to_batadv: link becomes ready nbd_start_device+0x1b6/0xc50 drivers/block/nbd.c:1201 batman_adv: The newly added mac address (aa:aa:aa:aa:aa:3e) already exists on: batadv_slave_1 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 batman_adv: It is strongly recommended to keep mac addresses unique to avoid problems! 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 IPv6: ADDRCONF(NETDEV_UP): batadv_slave_1: link is not ready batman_adv: batadv0: Interface activated: batadv_slave_1 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:00007fecc356c198 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: 00007fecc356c6bc 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 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: ffff8881db5779e0 RIP: cpumask_set_cpu include/linux/cpumask.h:283 [inline] RSP: ffff8881db5779e0 RIP: blk_mq_map_swqueue+0x23a/0xa90 block/blk-mq.c:2171 RSP: ffff8881db5779e0 CR2: 0000000000000120 device veth0_vlan entered promiscuous mode ---[ end trace 93dc732c044dc31a ]--- batman_adv: The newly added mac address (aa:aa:aa:aa:aa:3e) already exists on: batadv_slave_1