FYI, we noticed the following commit (built with gcc-7):

commit: 987f028b8637cfa7658aa456ae73f8f21a7a7f6f ("char: hpet: Use flexible-array member")
https://git.kernel.org/cgit/linux/kernel/git/gregkh/char-misc.git char-misc-next

in testcase: blktests
with following parameters:

	disk: 1SSD
	test: nvme-005



on test machine: qemu-system-x86_64 -enable-kvm -cpu SandyBridge -smp 2 -m 8G

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


+------------------------------------------+------------+------------+
|                                          | eb143f8756 | 987f028b86 |
+------------------------------------------+------------+------------+
| boot_successes                           | 7          | 0          |
| boot_failures                            | 0          | 7          |
| stack_segment:#[##]                      | 0          | 7          |
| RIP:__kmalloc                            | 0          | 7          |
| Kernel_panic-not_syncing:Fatal_exception | 0          | 7          |
+------------------------------------------+------------+------------+


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


[    1.025991] NetLabel:  unlabeled traffic allowed by default
[    1.026375] hpet0: at MMIO 0xfed00000, IRQs 2, 8, 0
[    1.027093] hpet0: 3 comparators, 64-bit 100.000000 MHz counter
[    1.030128] clocksource: Switched to clocksource kvm-clock
[    1.084907] VFS: Disk quotas dquot_6.6.0
[    1.086158] stack segment: 0000 [#1] SMP PTI
[    1.087100] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.5.0-rc7-00103-g987f028b8637c #1
[    1.087100] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1 04/01/2014
[    1.087100] RIP: 0010:__kmalloc+0x9d/0x270
[    1.087100] Code: 01 00 00 4d 8b 07 65 49 8b 50 08 65 4c 03 05 4a 37 b7 75 49 8b 28 48 85 ed 0f 84 a1 01 00 00 41 8b 47 20 4d 8b 07 48 8d 4a 01 <48> 8b 5c 05 00 48 89 e8 65 49 0f c7 08 0f 94 c0 84 c0 74 c5 41 8b
[    1.087100] RSP: 0000:ffffa4cb80013d28 EFLAGS: 00010202
[    1.087100] RAX: 0000000000000000 RBX: 0000000000000dc0 RCX: 0000000000000133
[    1.087100] RDX: 0000000000000132 RSI: 0000000000000dc0 RDI: ffff981247c02fc0
[    1.087100] RBP: 009896808086a201 R08: 0000000000031120 R09: ffff981274887e00
[    1.087100] R10: ffffa4cb80013d78 R11: 0000000000000000 R12: 0000000000000dc0
[    1.087100] R13: 00000000000000fe R14: ffff981247c02fc0 R15: ffff981247c02fc0
[    1.087100] FS:  0000000000000000(0000) GS:ffff98137fc00000(0000) knlGS:0000000000000000
[    1.087100] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[    1.087100] CR2: 0000000000000000 CR3: 0000000133a0a000 CR4: 00000000000406f0
[    1.087100] Call Trace:
[    1.087100]  ? __register_sysctl_table+0x44e/0x5e0
[    1.087100]  __register_sysctl_table+0x44e/0x5e0
[    1.087100]  ? kmem_cache_alloc_trace+0x3b/0x230
[    1.087100]  __register_sysctl_paths+0x1c0/0x1f0
[    1.087100]  ? set_debug_rodata+0x11/0x11
[    1.087100]  dquot_init+0x2f/0x116
[    1.087100]  ? iomap_init+0x20/0x20
[    1.087100]  do_one_initcall+0x46/0x220
[    1.087100]  kernel_init_freeable+0x1c2/0x23b
[    1.087100]  ? rest_init+0xd0/0xd0
[    1.087100]  kernel_init+0xa/0x110
[    1.087100]  ret_from_fork+0x35/0x40
[    1.087100] Modules linked in:
[    1.115829] ---[ end trace bc28001aba492303 ]---
[    1.116611] RIP: 0010:__kmalloc+0x9d/0x270
[    1.117313] Code: 01 00 00 4d 8b 07 65 49 8b 50 08 65 4c 03 05 4a 37 b7 75 49 8b 28 48 85 ed 0f 84 a1 01 00 00 41 8b 47 20 4d 8b 07 48 8d 4a 01 <48> 8b 5c 05 00 48 89 e8 65 49 0f c7 08 0f 94 c0 84 c0 74 c5 41 8b
[    1.120074] RSP: 0000:ffffa4cb80013d28 EFLAGS: 00010202
[    1.120940] RAX: 0000000000000000 RBX: 0000000000000dc0 RCX: 0000000000000133
[    1.122042] RDX: 0000000000000132 RSI: 0000000000000dc0 RDI: ffff981247c02fc0
[    1.123138] RBP: 009896808086a201 R08: 0000000000031120 R09: ffff981274887e00
[    1.124258] R10: ffffa4cb80013d78 R11: 0000000000000000 R12: 0000000000000dc0
[    1.125378] R13: 00000000000000fe R14: ffff981247c02fc0 R15: ffff981247c02fc0
[    1.126453] FS:  0000000000000000(0000) GS:ffff98137fc00000(0000) knlGS:0000000000000000
[    1.127787] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[    1.128716] CR2: 0000000000000000 CR3: 0000000133a0a000 CR4: 00000000000406f0
[    1.129807] Kernel panic - not syncing: Fatal exception


To reproduce:

        # build kernel
	cd linux
	cp config-5.5.0-rc7-00103-g987f028b8637c .config
	make HOSTCC=gcc-7 CC=gcc-7 ARCH=x86_64 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