FYI, we noticed the following commit (built with gcc-7): commit: a7361529939e80b6e182cf17f30e00545863f718 ("blk-mq: fix changelog") https://git.kernel.org/cgit/linux/kernel/git/gregkh/driver-core.git debugfs_cleanup in testcase: boot on test machine: qemu-system-x86_64 -enable-kvm -cpu SandyBridge -smp 2 -m 3G caused below changes (please refer to attached dmesg/kmsg for entire log/backtrace): +------------------------------------------------+------------+------------+ | | 23343defc4 | a736152993 | +------------------------------------------------+------------+------------+ | boot_successes | 5 | 0 | | boot_failures | 5 | 11 | | BUG:kernel_in_stage | 1 | | | IP-Config:Auto-configuration_of_network_failed | 4 | | | BUG:KASAN:null-ptr-deref_in_d | 0 | 11 | | BUG:unable_to_handle_kernel | 0 | 11 | | Oops:#[##] | 0 | 11 | | RIP:debugfs_create_files | 0 | 11 | | Kernel_panic-not_syncing:Fatal_exception | 0 | 11 | +------------------------------------------------+------------+------------+ [ 41.433960] BUG: KASAN: null-ptr-deref in debugfs_create_files+0x4e/0x82 [ 41.433960] Read of size 8 at addr 0000000000000000 by task kworker/u2:1/184 [ 41.433960] [ 41.433960] CPU: 0 PID: 184 Comm: kworker/u2:1 Not tainted 5.0.0-rc1-00108-ga736152 #1 [ 41.433960] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1 04/01/2014 [ 41.433960] Workqueue: events_unbound async_run_entry_fn [ 41.433960] Call Trace: [ 41.433960] ? debugfs_create_files+0x4e/0x82 [ 41.433960] kasan_report+0x123/0x136 [ 41.433960] ? debugfs_create_files+0x4e/0x82 [ 41.433960] debugfs_create_files+0x4e/0x82 [ 41.433960] blk_mq_debugfs_register+0x124/0x15e [ 41.433960] blk_register_queue+0x117/0x187 [ 41.433960] __device_add_disk+0x577/0x68c [ 41.433960] ? bdget_disk+0x3b/0x3b [ 41.433960] ? rpm_check_suspend_allowed+0x62/0x12d [ 41.433960] ? rpm_idle+0x15/0x187 [ 41.433960] ? preempt_count_sub+0x13/0xc0 [ 41.433960] sd_probe_async+0x1f1/0x2e2 [ 41.433960] ? sd_revalidate_disk+0x1995/0x1995 [ 41.433960] async_run_entry_fn+0x70/0x1c8 [ 41.433960] process_one_work+0x229/0x30f [ 41.433960] ? worker_clr_flags+0x56/0x98 [ 41.433960] worker_thread+0x29a/0x3c5 [ 41.433960] ? process_scheduled_works+0x37/0x37 [ 41.433960] kthread+0x19f/0x1ae [ 41.433960] ? __kthread_cancel_work+0xb2/0xb2 [ 41.433960] ret_from_fork+0x35/0x40 [ 41.433960] ================================================================== [ 41.433960] Disabling lock debugging due to kernel taint [ 41.462550] db_root: cannot open: /etc/target [ 41.464118] L440GX flash mapping: failed to find PIIX4 ISA bridge, cannot continue [ 41.465617] device id = 2440 [ 41.466288] device id = 2480 [ 41.466929] device id = 24c0 [ 41.467588] device id = 24d0 [ 41.468242] device id = 25a1 [ 41.468879] device id = 2670 [ 41.469706] platform physmap-flash.0: failed to claim resource 0: [mem 0x08000000-0x07ffffff] [ 41.471900] Ramix PMC551 PCI Mezzanine Ram Driver. (C) 1999,2000 Nortel Networks. [ 41.473363] pmc551: not detected [ 41.480628] BUG: unable to handle kernel NULL pointer dereference at 0000000000000000 [ 41.480958] #PF error: [normal kernel read fault] [ 41.480958] PGD 0 P4D 0 [ 41.480958] Oops: 0000 [#1] PREEMPT KASAN [ 41.480958] CPU: 0 PID: 1 Comm: swapper Tainted: G B 5.0.0-rc1-00108-ga736152 #1 [ 41.480958] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1 04/01/2014 [ 41.480958] RIP: 0010:debugfs_create_files+0x4e/0x82 [ 41.480958] Code: b1 ff 4c 8b 65 30 49 8d bc 24 10 02 00 00 e8 11 b8 b1 ff 4d 89 ac 24 10 02 00 00 49 c7 c5 e0 16 25 83 48 89 df e8 5e b7 b1 ff <4c> 8b 23 4d 85 e4 74 24 48 8d 7b 08 e8 e5 b4 b1 ff 0f b7 73 08 48 [ 41.480958] RSP: 0000:ffff8880a38a7b68 EFLAGS: 00010282 [ 41.480958] RAX: 0000000000000001 RBX: 0000000000000000 RCX: ffffffff816bd8c8 [ 41.480958] RDX: 0000000000000000 RSI: 0000000000000008 RDI: 0000000000000000 [ 41.480958] RBP: ffff88808fdea700 R08: ffff88808fdea738 R09: 0000000000000007 [ 41.480958] R10: 0000000000000001 R11: ffff88808dfaa16f R12: ffff88808dfaa000 [ 41.480958] R13: ffffffff832516e0 R14: ffff88808d248838 R15: ffff88808d248868 [ 41.480958] FS: 0000000000000000(0000) GS:ffffffff8407d000(0000) knlGS:0000000000000000 [ 41.480958] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 41.480958] CR2: 0000000000000000 CR3: 000000000402f000 CR4: 00000000000406f0 [ 41.480958] Call Trace: [ 41.480958] blk_mq_debugfs_register+0x124/0x15e [ 41.480958] blk_register_queue+0x117/0x187 [ 41.480958] __device_add_disk+0x577/0x68c [ 41.480958] ? bdget_disk+0x3b/0x3b [ 41.480958] ? blk_mq_init_allocated_queue+0x5f3/0x63f [ 41.480958] ? blk_mq_init_queue+0x36/0x52 [ 41.480958] ? blk_mq_alloc_tag_set+0x363/0x40e [ 41.480958] add_mtd_blktrans_dev+0x4e3/0x575 [ 41.480958] ? kasan_kmalloc+0x89/0x9a [ 41.480958] mtdblock_add_mtd+0xb1/0xca [ 41.480958] blktrans_notify_add+0x42/0x59 [ 41.480958] add_mtd_device+0x37d/0x3d4 [ 41.480958] mtd_device_parse_register+0xc9/0x1de [ 41.480958] ? set_debug_rodata+0xc/0xc [ 41.480958] mtdram_init_device+0x12b/0x13b [ 41.480958] init_mtdram+0x75/0xca [ 41.480958] ? init_pmc551+0x532/0x532 [ 41.480958] do_one_initcall+0xc3/0x1b6 [ 41.480958] ? start_kernel+0x4ad/0x4ad [ 41.480958] ? __memset+0x29/0x30 [ 41.480958] ? ___might_sleep+0x78/0x1fb [ 41.480958] kernel_init_freeable+0x190/0x221 [ 41.480958] ? rest_init+0xc1/0xc1 [ 41.480958] kernel_init+0x7/0xf9 [ 41.480958] ? rest_init+0xc1/0xc1 [ 41.480958] ret_from_fork+0x35/0x40 [ 41.480958] CR2: 0000000000000000 [ 41.480958] ---[ end trace db039e7dd4e1d779 ]--- To reproduce: git clone https://github.com/intel/lkp-tests.git cd lkp-tests bin/lkp qemu -k job-script # job-script is attached in this email Thanks, lkp