Greeting,

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

commit: 5da9e742d1934e86760f02caa769eecb239feafe ("[RFC][PATCH v2 12/21] x86/pti: Use PTI stack instead of trampoline stack")
url: https://github.com/0day-ci/linux/commits/Alexandre-Chartre/x86-pti-Defer-CR3-switch-to-C-code/20201116-225620
base: https://git.kernel.org/cgit/linux/kernel/git/tip/tip.git 1fcd009102ee02e217f2e7635ab65517d785da8e

in testcase: boot

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):


+-------------------------------------------------------+------------+------------+
|                                                       | f2df5fbe42 | 5da9e742d1 |
+-------------------------------------------------------+------------+------------+
| PANIC:double_fault                                    | 0          | 4          |
| double_fault:#[##]                                    | 0          | 4          |
| Kernel_panic-not_syncing:Fatal_exception_in_interrupt | 0          | 4          |
+-------------------------------------------------------+------------+------------+


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


[    6.786553] Loading compiled-in X.509 certificates
[    6.788127] zswap: loaded using pool lzo/zbud
[    6.789836] Key type ._fscrypt registered
[    6.791177] Key type .fscrypt registered
[    6.792501] Key type fscrypt-provisioning registered
[    6.794677] traps: PANIC: double fault, error_code: 0x0
[    6.794679] double fault: 0000 [#1] SMP PTI
[    6.794680] CPU: 0 PID: 87 Comm: modprobe Not tainted 5.10.0-rc1-00013-g5da9e742d193 #1
[    6.794681] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-1 04/01/2014
[    6.794681] RIP: 0023:0xf7fd507d
[    6.794683] Code: 8b 4c 24 04 53 56 57 55 8b 01 85 c0 75 23 8b 44 24 18 8b 5c 24 1c 8b 4c 24 20 8b 54 24 24 8b 74 24 28 8b 7c 24 2c 8b 6c 24 30 <cd> 80 5d 5f 5e 5b c3 5d 5f 5e 5b e9 30 09 00 00 65 8b 15 04 00 00
[    6.794684] RSP: 002b:00000000fffc710c EFLAGS: 00010246
[    6.794686] RAX: 0000000000000005 RBX: 00000000fffc7330 RCX: 0000000000088000
[    6.794687] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
[    6.794688] RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
[    6.794689] R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
[    6.794690] R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
[    6.794690] FS:  0000000000000000 GS:  00000000f7ff1de4
[    6.794691] Modules linked in:
[    6.824939] ---[ end trace 2d660ddeebdfa224 ]---
[    6.824941] RIP: 0023:0xf7fd507d
[    6.824942] Code: 8b 4c 24 04 53 56 57 55 8b 01 85 c0 75 23 8b 44 24 18 8b 5c 24 1c 8b 4c 24 20 8b 54 24 24 8b 74 24 28 8b 7c 24 2c 8b 6c 24 30 <cd> 80 5d 5f 5e 5b c3 5d 5f 5e 5b e9 30 09 00 00 65 8b 15 04 00 00
[    6.824943] RSP: 002b:00000000fffc710c EFLAGS: 00010246
[    6.824945] RAX: 0000000000000005 RBX: 00000000fffc7330 RCX: 0000000000088000
[    6.824946] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
[    6.824947] RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
[    6.824948] R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
[    6.824949] R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
[    6.824950] FS:  0000000000000000(0000) GS:ffff88823fc00000(0063) knlGS:00000000f7ff1de4
[    6.824950] CS:  0023 DS: 002b ES: 002b CR0: 0000000080050033
[    6.824952] CR2: ffffc9000032fff8 CR3: 000000012fd52000 CR4: 00000000000406f0
[    6.824953] Kernel panic - not syncing: Fatal exception in interrupt
[    6.825052] Kernel Offset: disabled

Kboot worker: lkp-worker11
Elapsed time: 60



To reproduce:

        # build kernel
	cd linux
	cp config-5.10.0-rc1-00013-g5da9e742d193 .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 <bzImage> job-script # job-script is attached in this email



Thanks,
Oliver Sang