Greeting,

FYI, we noticed the following commit (built with gcc-9):

commit: 4e88ec4a9eb17527e640b063f79e5b875733eb53 ("rcuperf: Change rcuperf to rcuscale")
https://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git master


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-i386 -enable-kvm -cpu SandyBridge -smp 2 -m 8G

caused below changes (please refer to attached dmesg/kmsg for entire log/backtrace):


+---------------------------------------------------------+------------+------------+
|                                                         | 65bd77f554 | 4e88ec4a9e |
+---------------------------------------------------------+------------+------------+
| boot_successes                                          | 13         | 0          |
| boot_failures                                           | 0          | 14         |
| UBSAN:division-overflow_in_arch/x86/include/asm/div64.h | 0          | 14         |
| error:#[##]                                             | 0          | 14         |
| EIP:main_func.cold                                      | 0          | 14         |
| Kernel_panic-not_syncing:Fatal_exception                | 0          | 14         |
+---------------------------------------------------------+------------+------------+


If you fix the issue, kindly add following tag
Reported-by: kernel test robot <lkp@intel.com>


[   24.821408] UBSAN: division-overflow in arch/x86/include/asm/div64.h:54:20
[   24.823429] division by zero
[   24.824123] CPU: 0 PID: 64 Comm: main_func Not tainted 5.9.0-rc1-00019-g4e88ec4a9eb17 #1
[   24.825684] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-1 04/01/2014
[   24.827073] Call Trace:
[   24.827523]  dump_stack+0x45/0x66
[   24.828139]  ubsan_epilogue+0x16/0x75
[   24.828843]  __ubsan_handle_divrem_overflow.cold+0x10f/0x1b0
[   24.834661]  ? destroy_timer_on_stack+0x40/0x40
[   24.835417]  ? __might_sleep+0x88/0x140
[   24.836116]  main_func.cold+0xb3/0x36d
[   24.836878]  ? __lock_release+0x62/0x340
[   24.837565]  ? __kthread_parkme+0xd2/0x140
[   24.838337]  kthread+0x2c5/0x320
[   24.838970]  ? kzalloc+0x40/0x40
[   24.839806]  ? kthread_create_worker+0x40/0x40
[   24.840709]  ret_from_fork+0x1c/0x28
[   24.841427] ================================================================================
[   24.842989] divide_error: 0000 [#1]
[   24.843812] CPU: 0 PID: 64 Comm: main_func Not tainted 5.9.0-rc1-00019-g4e88ec4a9eb17 #1
[   24.845435] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-1 04/01/2014
[   24.847007] EIP: main_func.cold+0xb7/0x36d
[   24.847763] Code: 15 14 4b c5 c2 00 5e e9 f0 f7 ff ff 83 05 d0 3e c5 c2 01 b8 30 c6 5e c2 83 15 d4 3e c5 c2 00 31 c9 e8 6c 03 4c 00 89 d8 31 d2 <f7> f6 83 05 d8 3e c5 c2 01 89 da 83 15 dc 3e c5 c2 00 31 c9 89 c7
[   24.850835] EAX: 00000000 EBX: 00000000 ECX: 00000000 EDX: 00000000
[   24.851857] ESI: 00000000 EDI: 00000000 EBP: e8b91f84 ESP: e8b91ef8
[   24.852969] DS: 007b ES: 007b FS: 0000 GS: 00e0 SS: 0068 EFLAGS: 00010246
[   24.854183] CR0: 80050033 CR2: 096e3000 CR3: 29832160 CR4: 000406b0
[   24.855270] Call Trace:
[   24.855766]  ? __lock_release+0x62/0x340
[   24.856530]  ? __kthread_parkme+0xd2/0x140
[   24.857245]  kthread+0x2c5/0x320
[   24.857759]  ? kzalloc+0x40/0x40
[   24.858547]  ? kthread_create_worker+0x40/0x40
[   24.859387]  ret_from_fork+0x1c/0x28
[   24.860081] Modules linked in: serio_raw i2c_piix4 i2c_core
[   24.861149] ---[ end trace 59d328920e1c098a ]---


To reproduce:

        # build kernel
	cd linux
	cp config-5.9.0-rc1-00019-g4e88ec4a9eb17 .config
	make HOSTCC=gcc-9 CC=gcc-9 ARCH=i386 olddefconfig prepare modules_prepare bzImage

        git clone https://github.com/intel/lkp-tests.git
        cd lkp-tests
        bin/lkp qemu -k <bzImage> job-script # job-script is attached in this email



Thanks,
lkp