Greeting, FYI, we noticed the following commit (built with gcc-9): commit: e3b1cb5c896ba748d8f848238c8ea1f89520bde3 ("[PATCH 3/3] driver core: Avoid adding children below a dead parent") url: https://github.com/0day-ci/linux/commits/Lukas-Wunner/Fix-races-on-device-removal/20200708-214117 base: https://git.kernel.org/cgit/linux/kernel/git/gregkh/driver-core.git e5711945c6415ab847b39ef89003ef68f9435bc6 in testcase: trinity with following parameters: runtime: 300s test-description: Trinity is a linux system call fuzz tester. test-url: http://codemonkey.org.uk/projects/trinity/ on test machine: qemu-system-x86_64 -enable-kvm -cpu SandyBridge -smp 2 -m 16G caused below changes (please refer to attached dmesg/kmsg for entire log/backtrace): +-------------------------------------------------------+------------+------------+ | | 1cf28805e6 | e3b1cb5c89 | +-------------------------------------------------------+------------+------------+ | boot_successes | 0 | 0 | | boot_failures | 10 | 4 | | WARNING:possible_circular_locking_dependency_detected | 10 | | | BUG:workqueue_lockup-pool | 1 | 1 | | INFO:rcu_sched_detected_stalls_on_CPUs/tasks | 1 | | | RIP:do_syscall_64 | 1 | | | BUG:soft_lockup-CPU##stuck_for#s![kworker:#:#] | 1 | | | RIP:smp_call_function_single | 1 | | | Kernel_panic-not_syncing:softlockup:hung_tasks | 1 | | | WARNING:possible_recursive_locking_detected | 0 | 4 | +-------------------------------------------------------+------------+------------+ If you fix the issue, kindly add following tag Reported-by: kernel test robot [ 1.392584] WARNING: possible recursive locking detected [ 1.393350] 5.8.0-rc3-00011-ge3b1cb5c896ba7 #1 Not tainted [ 1.393350] -------------------------------------------- [ 1.393350] swapper/0/1 is trying to acquire lock: [ 1.393350] ffff88841fc6ff70 (&dev->p->dead_sem){.+.+}-{3:3}, at: __device_attach+0x51/0x1a0 [ 1.393350] [ 1.393350] but task is already holding lock: [ 1.393350] ffff888107f42770 (&dev->p->dead_sem){.+.+}-{3:3}, at: device_add+0xf8/0x890 [ 1.393350] [ 1.393350] other info that might help us debug this: [ 1.393350] Possible unsafe locking scenario: [ 1.393350] [ 1.393350] CPU0 [ 1.393350] ---- [ 1.393350] lock(&dev->p->dead_sem); [ 1.393350] [ 1.393350] *** DEADLOCK *** [ 1.393350] [ 1.393350] May be due to missing lock nesting notation [ 1.393350] [ 1.393350] 2 locks held by swapper/0/1: [ 1.393350] #0: ffff888107f42770 (&dev->p->dead_sem){.+.+}-{3:3}, at: device_add+0xf8/0x890 [ 1.393350] #1: ffff88841fc6b188 (&dev->mutex){....}-{3:3}, at: __device_attach+0x3e/0x1a0 [ 1.393350] [ 1.393350] stack backtrace: [ 1.393350] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.8.0-rc3-00011-ge3b1cb5c896ba7 #1 [ 1.393350] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-1 04/01/2014 [ 1.393350] Call Trace: [ 1.393350] dump_stack+0x81/0xba [ 1.393350] validate_chain.cold+0x132/0x167 [ 1.393350] __lock_acquire+0x570/0xb60 [ 1.393350] lock_acquire+0xba/0x390 [ 1.393350] ? __device_attach+0x51/0x1a0 [ 1.393350] down_read+0x47/0x140 [ 1.393350] ? __device_attach+0x51/0x1a0 [ 1.393350] __device_attach+0x51/0x1a0 [ 1.393350] device_initial_probe+0xe/0x10 [ 1.393350] bus_probe_device+0x98/0xb0 [ 1.393350] device_add+0x421/0x890 [ 1.393350] platform_device_add+0xee/0x240 [ 1.393350] regulator_dummy_init+0x35/0x83 [ 1.393350] regulator_init+0x89/0x9c [ 1.393350] ? regulator_init_complete+0x25/0x25 [ 1.393350] do_one_initcall+0x63/0x330 [ 1.393350] ? rcu_read_lock_sched_held+0x4a/0x80 [ 1.393350] kernel_init_freeable+0x1fb/0x25f [ 1.393350] ? rest_init+0x24d/0x24d [ 1.393350] kernel_init+0x9/0x103 [ 1.393350] ret_from_fork+0x1f/0x30 [ 1.393605] thermal_sys: Registered thermal governor 'step_wise' [ 1.393919] NET: Registered protocol family 16 [ 1.396950] EISA bus registered [ 1.397389] cpuidle: using governor ladder [ 1.398250] cpuidle: using governor teo [ 1.399807] ACPI: bus type PCI registered [ 1.400804] PCI: Using configuration type 1 for base access [ 1.417603] HugeTLB registered 2.00 MiB page size, pre-allocated 0 pages [ 1.433475] cryptd: max_cpu_qlen set to 1000 [ 1.641498] ACPI: Added _OSI(Module Device) [ 1.642377] ACPI: Added _OSI(Processor Device) [ 1.643143] ACPI: Added _OSI(3.0 _SCP Extensions) [ 1.643964] ACPI: Added _OSI(Processor Aggregator Device) [ 1.644961] ACPI: Added _OSI(Linux-Dell-Video) [ 1.645365] ACPI: Added _OSI(Linux-Lenovo-NV-HDMI-Audio) [ 1.646421] ACPI: Added _OSI(Linux-HPI-Hybrid-Graphics) [ 1.652593] ACPI: 1 ACPI AML tables successfully acquired and loaded [ 1.658595] ACPI: Interpreter enabled [ 1.659418] ACPI: (supports S0 S5) [ 1.660097] ACPI: Using IOAPIC for interrupt routing [ 1.661137] PCI: Using host bridge windows from ACPI; if necessary, use "pci=nocrs" and report a bug [ 1.661810] ACPI: Enabled 2 GPEs in block 00 to 0F [ 1.679128] ACPI: PCI Root Bridge [PCI0] (domain 0000 [bus 00-ff]) [ 1.680444] acpi PNP0A03:00: _OSC: OS supports [ASPM ClockPM Segments HPX-Type3] [ 1.681408] acpi PNP0A03:00: fail to add MMCONFIG information, can't access extended PCI configuration space under this bridge. [ 1.684010] PCI host bridge to bus 0000:00 [ 1.684843] pci_bus 0000:00: root bus resource [io 0x0000-0x0cf7 window] [ 1.685366] pci_bus 0000:00: root bus resource [io 0x0d00-0xffff window] [ 1.686820] pci_bus 0000:00: root bus resource [mem 0x000a0000-0x000bffff window] [ 1.688259] pci_bus 0000:00: root bus resource [mem 0xc0000000-0xfebfffff window] [ 1.689367] pci_bus 0000:00: root bus resource [mem 0x440000000-0x4bfffffff window] [ 1.691002] pci_bus 0000:00: root bus resource [bus 00-ff] [ 1.692175] pci 0000:00:00.0: [8086:1237] type 00 class 0x060000 [ 1.694191] pci 0000:00:01.0: [8086:7000] type 00 class 0x060100 [ 1.696487] pci 0000:00:01.1: [8086:7010] type 00 class 0x010180 [ 1.705090] pci 0000:00:01.1: reg 0x20: [io 0xc200-0xc20f] [ 1.708092] pci 0000:00:01.1: legacy IDE quirk: reg 0x10: [io 0x01f0-0x01f7] [ 1.709365] pci 0000:00:01.1: legacy IDE quirk: reg 0x14: [io 0x03f6] [ 1.710633] pci 0000:00:01.1: legacy IDE quirk: reg 0x18: [io 0x0170-0x0177] [ 1.712030] pci 0000:00:01.1: legacy IDE quirk: reg 0x1c: [io 0x0376] [ 1.713916] pci 0000:00:01.3: [8086:7113] type 00 class 0x068000 [ 1.715635] pci 0000:00:01.3: quirk: [io 0x0600-0x063f] claimed by PIIX4 ACPI [ 1.717241] pci 0000:00:01.3: quirk: [io 0x0700-0x070f] claimed by PIIX4 SMB [ 1.717974] pci 0000:00:02.0: [1234:1111] type 00 class 0x030000 [ 1.722816] pci 0000:00:02.0: reg 0x10: [mem 0xfd000000-0xfdffffff pref] [ 1.730758] pci 0000:00:02.0: reg 0x18: [mem 0xfebf0000-0xfebf0fff] [ 1.744295] pci 0000:00:02.0: reg 0x30: [mem 0xfebe0000-0xfebeffff pref] [ 1.746003] pci 0000:00:03.0: [8086:100e] type 00 class 0x020000 [ 1.750471] pci 0000:00:03.0: reg 0x10: [mem 0xfebc0000-0xfebdffff] [ 1.753367] pci 0000:00:03.0: reg 0x14: [io 0xc000-0xc03f] [ 1.769371] pci 0000:00:03.0: reg 0x30: [mem 0xfeb80000-0xfebbffff pref] [ 1.771401] pci 0000:00:04.0: [1af4:1001] type 00 class 0x010000 To reproduce: # build kernel cd linux cp config-5.8.0-rc3-00011-ge3b1cb5c896ba7 .config make HOSTCC=gcc-9 CC=gcc-9 ARCH=x86_64 olddefconfig prepare modules_prepare bzImage 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, Rong Chen