bisecting fixing commit since 312017a460d5ea31d646e7148e400e13db799ddc building syzkaller on eef6e5808d6507716d331b9eff67fdd991be891a testing commit 312017a460d5ea31d646e7148e400e13db799ddc with gcc (GCC) 8.1.0 kernel signature: 661b2c8782ca3f189be82a14cc1d4cb6b5dc1b5c 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 NULL pointer dereference in blk_mq_map_swqueue run #3: crashed: BUG: unable to handle kernel NULL pointer dereference in corrupted run #4: crashed: BUG: unable to handle kernel NULL pointer dereference in corrupted run #5: crashed: BUG: unable to handle kernel NULL pointer dereference in blk_mq_map_swqueue 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 corrupted testing current HEAD dcd888983542055210f5e68f1b1f1f8fe11a369a testing commit dcd888983542055210f5e68f1b1f1f8fe11a369a with gcc (GCC) 8.1.0 kernel signature: 3f32fd6722760e35ba6648885ca640078d5b49f6 all runs: crashed: BUG: unable to handle kernel NULL pointer dereference in blk_mq_map_swqueue revisions tested: 2, total time: 25m50.074177782s (build: 18m57.238484192s, test: 6m26.956593711s) the crash still happens on HEAD commit msg: Linux 4.19.95 crash: BUG: unable to handle kernel NULL pointer dereference in blk_mq_map_swqueue kobject: '0' (0000000033aab91b): kobject_add_internal: parent: 'mq', set: '' kobject: 'cpu1' (000000000316e4b6): kobject_add_internal: parent: '0', set: '' kobject: 'cpu0' (000000004e8f3fce): kobject_add_internal: parent: '0', set: '' BUG: unable to handle kernel NULL pointer dereference at 0000000000000118 kobject: 'cpu1' (000000006d34bf76): kobject_add_internal: parent: '0', set: '' PGD 93412067 P4D 93412067 PUD 94230067 PMD 0 kobject: '0' (0000000033aab91b): kobject_add_internal: parent: 'mq', set: '' Oops: 0002 [#1] PREEMPT SMP KASAN CPU: 1 PID: 7331 Comm: syz-executor.0 Not tainted 4.19.95-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:set_bit arch/x86/include/asm/bitops.h:76 [inline] RIP: 0010:cpumask_set_cpu include/linux/cpumask.h:311 [inline] RIP: 0010:blk_mq_map_swqueue+0x269/0xb00 block/blk-mq.c:2344 Code: 0f 85 37 07 00 00 8b 00 49 8d 04 c0 48 89 c7 48 c1 ef 03 42 80 3c 3f 00 0f 85 f4 06 00 00 83 fa 3f 4c 8b 00 0f 87 4a 04 00 00 4d 0f ab 88 18 01 00 00 49 8d b8 74 01 00 00 48 89 f8 48 c1 e8 RSP: 0018:ffff88808fc0f8a8 EFLAGS: 00010293 RAX: ffff8880a3de9708 RBX: 0000000000000007 RCX: 0000000000000000 RDX: 0000000000000001 RSI: ffffe8ffffd35340 RDI: 1ffff110147bd2e1 RBP: ffff88808fc0f920 R08: 0000000000000000 R09: 0000000000000001 R10: 0000000000000000 R11: ffff8880a3faff83 R12: ffff888218cdba40 R13: fffffbfff1244c36 R14: ffff8880a3df80c0 R15: dffffc0000000000 FS: 00007f3f72cd1700(0000) GS:ffff8880aeb00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000118 CR3: 0000000093e72000 CR4: 00000000001406e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: blk_mq_queue_reinit block/blk-mq.c:2686 [inline] __blk_mq_update_nr_hw_queues block/blk-mq.c:3007 [inline] blk_mq_update_nr_hw_queues+0x68a/0xb50 block/blk-mq.c:3021 kobject: 'cpu0' (000000004e8f3fce): kobject_add_internal: parent: '0', set: '' nbd_start_device+0x1b6/0xc10 drivers/block/nbd.c:1200 nbd_start_device_ioctl drivers/block/nbd.c:1241 [inline] __nbd_ioctl drivers/block/nbd.c:1323 [inline] nbd_ioctl+0x1b6/0xb20 drivers/block/nbd.c:1363 __blkdev_driver_ioctl block/ioctl.c:303 [inline] blkdev_ioctl+0x7a0/0x16d0 block/ioctl.c:601 block_ioctl+0xd7/0x130 fs/block_dev.c:1894 vfs_ioctl fs/ioctl.c:46 [inline] file_ioctl fs/ioctl.c:501 [inline] do_vfs_ioctl+0x196/0x10c0 fs/ioctl.c:688 ksys_ioctl+0x62/0x90 fs/ioctl.c:705 __do_sys_ioctl fs/ioctl.c:712 [inline] __se_sys_ioctl fs/ioctl.c:710 [inline] __x64_sys_ioctl+0x6e/0xb0 fs/ioctl.c:710 do_syscall_64+0xd0/0x4e0 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x45a909 Code: ad b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 7b b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007f3f72cd0c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 kobject: '1' (00000000e0b3bb51): kobject_add_internal: parent: 'mq', set: '' RAX: ffffffffffffffda RBX: 00007f3f72cd0c90 RCX: 000000000045a909 RDX: 0000000000000000 RSI: 000000000000ab03 RDI: 0000000000000003 RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007f3f72cd16d4 R13: 00000000004c4670 R14: 00000000004d9da0 R15: 0000000000000007 Modules linked in: CR2: 0000000000000118 FAULT_INJECTION: forcing a failure. name failslab, interval 1, probability 0, space 0, times 0 kobject: 'cpu1' (000000006d34bf76): kobject_add_internal: parent: '1', set: '' kobject: 'iosched' (000000001ee5bd7b): kobject_uevent_env kobject: 'iosched' (00000000db2fb428): kobject_add_internal: parent: 'queue', set: '' kobject: 'iosched' (000000001ee5bd7b): kobject_uevent_env: filter function caused the event to drop! CPU: 0 PID: 7345 Comm: syz-executor.1 Tainted: G D 4.19.95-syzkaller #0 kobject: 'iosched' (0000000053a6be04): kobject_uevent_env Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x123/0x177 lib/dump_stack.c:118 fail_dump lib/fault-inject.c:51 [inline] should_fail.cold.4+0x5/0x13 lib/fault-inject.c:149 __should_failslab+0xba/0xf0 mm/failslab.c:32 should_failslab+0x9/0x14 mm/slab_common.c:1557 slab_pre_alloc_hook mm/slab.h:424 [inline] slab_alloc mm/slab.c:3383 [inline] kmem_cache_alloc_trace+0x2d4/0x740 mm/slab.c:3623 kmalloc include/linux/slab.h:515 [inline] blk_mq_elv_switch_none block/blk-mq.c:2928 [inline] __blk_mq_update_nr_hw_queues block/blk-mq.c:3000 [inline] blk_mq_update_nr_hw_queues+0x427/0xb50 block/blk-mq.c:3021 nbd_start_device+0x1b6/0xc10 drivers/block/nbd.c:1200 nbd_start_device_ioctl drivers/block/nbd.c:1241 [inline] __nbd_ioctl drivers/block/nbd.c:1323 [inline] nbd_ioctl+0x1b6/0xb20 drivers/block/nbd.c:1363 FAULT_INJECTION: forcing a failure. name failslab, interval 1, probability 0, space 0, times 0 __blkdev_driver_ioctl block/ioctl.c:303 [inline] blkdev_ioctl+0x7a0/0x16d0 block/ioctl.c:601 kobject: 'iosched' (0000000053a6be04): kobject_uevent_env: filter function caused the event to drop! kobject: 'iosched' (000000001ee5bd7b): kobject_cleanup, parent (null) block_ioctl+0xd7/0x130 fs/block_dev.c:1894 vfs_ioctl fs/ioctl.c:46 [inline] file_ioctl fs/ioctl.c:501 [inline] do_vfs_ioctl+0x196/0x10c0 fs/ioctl.c:688 kobject: 'iosched' (0000000053a6be04): kobject_cleanup, parent (null) kobject: 'iosched' (0000000053a6be04): calling ktype release ksys_ioctl+0x62/0x90 fs/ioctl.c:705 __do_sys_ioctl fs/ioctl.c:712 [inline] __se_sys_ioctl fs/ioctl.c:710 [inline] __x64_sys_ioctl+0x6e/0xb0 fs/ioctl.c:710 kobject: 'iosched' (000000001ee5bd7b): calling ktype release do_syscall_64+0xd0/0x4e0 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x45a909 Code: ad b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 7b b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007fc161e55c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007fc161e55c90 RCX: 000000000045a909 RDX: 0000000000000000 RSI: 000000000000ab03 RDI: 0000000000000003 RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007fc161e566d4 R13: 00000000004c4670 R14: 00000000004d9da0 R15: 0000000000000007 kobject: 'iosched' (00000000db2fb428): kobject_uevent_env kobject: 'iosched': free name CPU: 0 PID: 7355 Comm: syz-executor.2 Tainted: G D 4.19.95-syzkaller #0 kobject: '0' (00000000195a3631): kobject_add_internal: parent: 'mq', set: '' Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x123/0x177 lib/dump_stack.c:118 fail_dump lib/fault-inject.c:51 [inline] should_fail.cold.4+0x5/0x13 lib/fault-inject.c:149 kobject: 'iosched': free name __should_failslab+0xba/0xf0 mm/failslab.c:32 should_failslab+0x9/0x14 mm/slab_common.c:1557 slab_pre_alloc_hook mm/slab.h:424 [inline] slab_alloc mm/slab.c:3383 [inline] kmem_cache_alloc_trace+0x2d4/0x740 mm/slab.c:3623 kmalloc include/linux/slab.h:515 [inline] blk_mq_elv_switch_none block/blk-mq.c:2928 [inline] __blk_mq_update_nr_hw_queues block/blk-mq.c:3000 [inline] blk_mq_update_nr_hw_queues+0x427/0xb50 block/blk-mq.c:3021 kobject: 'cpu0' (000000005eeffe33): kobject_add_internal: parent: '0', set: '' nbd_start_device+0x1b6/0xc10 drivers/block/nbd.c:1200 nbd_start_device_ioctl drivers/block/nbd.c:1241 [inline] __nbd_ioctl drivers/block/nbd.c:1323 [inline] nbd_ioctl+0x1b6/0xb20 drivers/block/nbd.c:1363 FAULT_INJECTION: forcing a failure. name failslab, interval 1, probability 0, space 0, times 0 __blkdev_driver_ioctl block/ioctl.c:303 [inline] blkdev_ioctl+0x7a0/0x16d0 block/ioctl.c:601 block_ioctl+0xd7/0x130 fs/block_dev.c:1894 vfs_ioctl fs/ioctl.c:46 [inline] file_ioctl fs/ioctl.c:501 [inline] do_vfs_ioctl+0x196/0x10c0 fs/ioctl.c:688 kobject: 'cpu1' (0000000006d0a72c): kobject_add_internal: parent: '0', set: '' kobject: '0' (00000000195a3631): kobject_add_internal: parent: 'mq', set: '' ksys_ioctl+0x62/0x90 fs/ioctl.c:705 __do_sys_ioctl fs/ioctl.c:712 [inline] __se_sys_ioctl fs/ioctl.c:710 [inline] __x64_sys_ioctl+0x6e/0xb0 fs/ioctl.c:710 do_syscall_64+0xd0/0x4e0 arch/x86/entry/common.c:293 kobject: 'cpu0' (000000005eeffe33): kobject_add_internal: parent: '0', set: '' entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x45a909 Code: ad b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 7b b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007f75e5f11c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007f75e5f11c90 RCX: 000000000045a909 RDX: 0000000000000000 RSI: 000000000000ab03 RDI: 0000000000000003 RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007f75e5f126d4 R13: 00000000004c4670 R14: 00000000004d9da0 R15: 0000000000000007 kobject: 'iosched' (00000000db2fb428): kobject_uevent_env: filter function caused the event to drop! CPU: 1 PID: 7352 Comm: syz-executor.5 Tainted: G D 4.19.95-syzkaller #0 kobject: 'nbd4' (000000005186777f): kobject_uevent_env Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x123/0x177 lib/dump_stack.c:118 fail_dump lib/fault-inject.c:51 [inline] should_fail.cold.4+0x5/0x13 lib/fault-inject.c:149 __should_failslab+0xba/0xf0 mm/failslab.c:32 should_failslab+0x9/0x14 mm/slab_common.c:1557 slab_pre_alloc_hook mm/slab.h:424 [inline] slab_alloc_node mm/slab.c:3304 [inline] kmem_cache_alloc_node_trace+0x26d/0x730 mm/slab.c:3666 __do_kmalloc_node mm/slab.c:3688 [inline] __kmalloc_node+0x3c/0x70 mm/slab.c:3696 kmalloc_node include/linux/slab.h:557 [inline] kzalloc_node include/linux/slab.h:720 [inline] blk_mq_realloc_hw_ctxs+0x19f/0xf50 block/blk-mq.c:2534 __blk_mq_update_nr_hw_queues block/blk-mq.c:3006 [inline] blk_mq_update_nr_hw_queues+0x6df/0xb50 block/blk-mq.c:3021 nbd_start_device+0x1b6/0xc10 drivers/block/nbd.c:1200 nbd_start_device_ioctl drivers/block/nbd.c:1241 [inline] __nbd_ioctl drivers/block/nbd.c:1323 [inline] nbd_ioctl+0x1b6/0xb20 drivers/block/nbd.c:1363 kobject: 'nbd4' (000000005186777f): fill_kobj_path: path = '/devices/virtual/block/nbd4' __blkdev_driver_ioctl block/ioctl.c:303 [inline] blkdev_ioctl+0x7a0/0x16d0 block/ioctl.c:601 block_ioctl+0xd7/0x130 fs/block_dev.c:1894 vfs_ioctl fs/ioctl.c:46 [inline] file_ioctl fs/ioctl.c:501 [inline] do_vfs_ioctl+0x196/0x10c0 fs/ioctl.c:688 ---[ end trace 8506abfd7521a0e4 ]--- block nbd4: Receive control failed (result -107) block nbd4: Receive control failed (result -107) ksys_ioctl+0x62/0x90 fs/ioctl.c:705 __do_sys_ioctl fs/ioctl.c:712 [inline] __se_sys_ioctl fs/ioctl.c:710 [inline] __x64_sys_ioctl+0x6e/0xb0 fs/ioctl.c:710 do_syscall_64+0xd0/0x4e0 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x45a909 Code: ad b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 7b b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007ffaa29e4c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007ffaa29e4c90 RCX: 000000000045a909 RDX: 0000000000000000 RSI: 000000000000ab03 RDI: 0000000000000003 RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007ffaa29e56d4 R13: 00000000004c4670 R14: 00000000004d9da0 R15: 0000000000000007 kobject: 'nbd2' (00000000930d0820): kobject_uevent_env block nbd2: Receive control failed (result -107) kobject: 'nbd4' (000000005186777f): kobject_uevent_env block nbd2: Receive control failed (result -107) kobject: 'nbd1' (00000000d1ee66ad): kobject_uevent_env kobject: '1' (0000000056e82fe7): kobject_add_internal: parent: 'mq', set: '' kobject: 'nbd2' (00000000930d0820): fill_kobj_path: path = '/devices/virtual/block/nbd2' kobject: 'nbd1' (00000000d1ee66ad): fill_kobj_path: path = '/devices/virtual/block/nbd1' kobject: 'nbd4' (000000005186777f): fill_kobj_path: path = '/devices/virtual/block/nbd4' block nbd2: shutting down sockets kobject: 'loop2' (000000002d302ca0): kobject_uevent_env kobject: '0' (00000000549a827c): kobject_add_internal: parent: 'mq', set: '' kobject: 'cpu0' (00000000ef38243a): kobject_add_internal: parent: '0', set: '' kobject: 'cpu1' (00000000ff4e238d): kobject_add_internal: parent: '0', set: '' BUG: unable to handle kernel NULL pointer dereference at 0000000000000118 kobject: 'cpu1' (0000000006d0a72c): kobject_add_internal: parent: '1', set: '' PGD 936fc067 P4D 936fc067 PUD 936fd067 PMD 0 Oops: 0002 [#2] PREEMPT SMP KASAN CPU: 0 PID: 7352 Comm: syz-executor.5 Tainted: G D 4.19.95-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:set_bit arch/x86/include/asm/bitops.h:76 [inline] RIP: 0010:cpumask_set_cpu include/linux/cpumask.h:311 [inline] RIP: 0010:blk_mq_map_swqueue+0x269/0xb00 block/blk-mq.c:2344 Code: 0f 85 37 07 00 00 8b 00 49 8d 04 c0 48 89 c7 48 c1 ef 03 42 80 3c 3f 00 0f 85 f4 06 00 00 83 fa 3f 4c 8b 00 0f 87 4a 04 00 00 4d 0f ab 88 18 01 00 00 49 8d b8 74 01 00 00 48 89 f8 48 c1 e8 RSP: 0018:ffff8880951d78a8 EFLAGS: 00010293 RAX: ffff8880a3e09488 RBX: 0000000000000007 RCX: 0000000000000000 RDX: 0000000000000001 RSI: ffffe8ffffd37a80 RDI: 1ffff110147c1291 RBP: ffff8880951d7920 R08: 0000000000000000 R09: 0000000000000001 R10: 0000000000000000 R11: ffff8880a395ff83 R12: ffff888218d60a80 R13: fffffbfff1244c36 R14: ffff8880a38e10c0 R15: dffffc0000000000 FS: 00007ffaa29e5700(0000) GS:ffff8880aea00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000118 CR3: 000000009397b000 CR4: 00000000001406f0 kobject: 'iosched' (00000000971ac1df): kobject_add_internal: parent: 'queue', set: '' DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000