bisecting fixing commit since 312017a460d5ea31d646e7148e400e13db799ddc building syzkaller on eef6e5808d6507716d331b9eff67fdd991be891a testing commit 312017a460d5ea31d646e7148e400e13db799ddc with gcc (GCC) 8.1.0 kernel signature: e3bdc541ff26ea9655b459087ade08d66129a2eca83bee54d42aaefa8550da3f 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 corrupted run #3: crashed: BUG: unable to handle kernel NULL pointer dereference in blk_mq_map_swqueue run #4: crashed: BUG: unable to handle kernel NULL pointer dereference in blk_mq_map_swqueue 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 blk_mq_map_swqueue testing current HEAD 357668399cf70ccdc0ee8967bff3448d0f4f9ae1 testing commit 357668399cf70ccdc0ee8967bff3448d0f4f9ae1 with gcc (GCC) 8.1.0 kernel signature: 6482d44cf3eccca5dfc13ee9672ebe3166f6056fd2f1940d7af45874bae4e5ea run #0: crashed: BUG: unable to handle kernel NULL pointer dereference in corrupted 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 corrupted run #3: crashed: BUG: unable to handle kernel NULL pointer dereference in blk_mq_map_swqueue run #4: crashed: BUG: unable to handle kernel NULL pointer dereference in blk_mq_map_swqueue run #5: crashed: BUG: unable to handle kernel NULL pointer dereference in corrupted 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 corrupted 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 revisions tested: 2, total time: 24m26.495571626s (build: 17m30.476967792s, test: 6m32.572325363s) the crash still happens on HEAD commit msg: Linux 4.19.103 crash: BUG: unable to handle kernel NULL pointer dereference in corrupted RDX: 0000000000000000 RSI: 000000000000ab03 RDI: 0000000000000003 RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007f87b4cb56d4 R13: 00000000004c4670 R14: 00000000004d9da0 R15: 0000000000000007 CPU: 0 PID: 7259 Comm: syz-executor.2 Not tainted 4.19.103-syzkaller #0 BUG: unable to handle kernel NULL pointer dereference at 0000000000000118 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 PGD 8d267067 P4D 8d267067 PUD 8df3a067 PMD 0 Call Trace: Oops: 0002 [#1] PREEMPT SMP KASAN __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x123/0x177 lib/dump_stack.c:118 CPU: 1 PID: 7246 Comm: syz-executor.5 Not tainted 4.19.103-syzkaller #0 fail_dump lib/fault-inject.c:51 [inline] should_fail.cold.4+0x5/0x13 lib/fault-inject.c:149 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 __should_failslab+0xba/0xf0 mm/failslab.c:32 RSP: 0018:ffff88809f35f8a8 EFLAGS: 00010293 should_failslab+0x9/0x14 mm/slab_common.c:1558 RAX: ffff8880a384ab48 RBX: 0000000000000007 RCX: 0000000000000000 slab_pre_alloc_hook mm/slab.h:424 [inline] slab_alloc mm/slab.c:3383 [inline] kmem_cache_alloc+0x2bc/0x730 mm/slab.c:3557 RDX: 0000000000000001 RSI: ffffe8ffffd37ac0 RDI: 1ffff11014709569 RBP: ffff88809f35f920 R08: 0000000000000000 R09: 0000000000000001 __d_alloc+0x28/0x9d0 fs/dcache.c:1610 R10: 0000000000000000 R11: ffff888091f3ff83 R12: ffff8880a3842000 d_alloc+0x42/0x220 fs/dcache.c:1694 R13: fffffbfff1244dde R14: ffff8880a384f0c0 R15: dffffc0000000000 d_alloc_parallel+0xf3/0x1750 fs/dcache.c:2441 FS: 00007f87b4cb5700(0000) GS:ffff8880aeb00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000118 CR3: 000000007dc07000 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 __lookup_slow+0x18d/0x400 fs/namei.c:1655 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 lookup_one_len+0x132/0x160 fs/namei.c:2544 __blkdev_driver_ioctl block/ioctl.c:303 [inline] blkdev_ioctl+0x7ae/0x16e0 block/ioctl.c:601 start_creating+0x91/0x190 fs/debugfs/inode.c:313 debugfs_create_dir+0x14/0x370 fs/debugfs/inode.c:510 nbd_dev_dbg_init drivers/block/nbd.c:1516 [inline] nbd_start_device+0x39a/0xc10 drivers/block/nbd.c:1212 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 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 __blkdev_driver_ioctl block/ioctl.c:303 [inline] blkdev_ioctl+0x7ae/0x16e0 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:00007f87b4cb4c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007f87b4cb4c90 RCX: 000000000045a909 RDX: 0000000000000000 RSI: 000000000000ab03 RDI: 0000000000000003 RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007f87b4cb56d4 R13: 00000000004c4670 R14: 00000000004d9da0 R15: 0000000000000007 Modules linked in: ksys_ioctl+0x62/0x90 fs/ioctl.c:705 CR2: 0000000000000118 ---[ end trace 9e3e6eb1a80d52bd ]--- __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: 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 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:00007fe12694bc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007fe12694bc90 RCX: 000000000045a909 RDX: 0000000000000000 RSI: 000000000000ab03 RDI: 0000000000000003 RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007fe12694c6d4 R13: 00000000004c4670 R14: 00000000004d9da0 R15: 0000000000000007 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 block nbd2: Failed to create debugfs dir for 'nbd2' block nbd0: shutting down sockets block nbd2: Receive control failed (result -107) block nbd4: shutting down sockets block nbd2: Receive control failed (result -107) RSP: 0018:ffff88809f35f8a8 EFLAGS: 00010293 block nbd2: shutting down sockets RAX: ffff8880a384ab48 RBX: 0000000000000007 RCX: 0000000000000000 block nbd1: shutting down sockets RDX: 0000000000000001 RSI: ffffe8ffffd37ac0 RDI: 1ffff11014709569 RBP: ffff88809f35f920 R08: 0000000000000000 R09: 0000000000000001 R10: 0000000000000000 R11: ffff888091f3ff83 R12: ffff8880a3842000 R13: fffffbfff1244dde R14: ffff8880a384f0c0 R15: dffffc0000000000 FS: 00007f87b4cb5700(0000) GS:ffff8880aeb00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000118 CR3: 000000007dc07000 CR4: 00000000001406e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400