FYI, we noticed the following commit:

commit: 39cd5a4ba8ad845ed384f43cdf4099e4cd10fa81 ("x86/fsgsbase/64: Preserve FS/GS state in __switch_to if FSGSBASE is on")
https://git.kernel.org/pub/scm/linux/kernel/git/luto/linux.git x86/fsgsbase

in testcase: aim9
with following parameters:

	testtime: 300s
	test: fork_test
	cpufreq_governor: performance

test-description: Suite IX is the "AIM Independent Resource Benchmark:" the famous synthetic benchmark.
test-url: https://sourceforge.net/projects/aimbench/files/aim-suite9/


on test machine: 4 threads Intel(R) Core(TM) i3-3220 CPU @ 3.30GHz with 4G memory

caused below changes:


+-------------------------------------------------+------------+------------+
|                                                 | b0f17dd81a | 39cd5a4ba8 |
+-------------------------------------------------+------------+------------+
| boot_successes                                  | 2          | 4          |
| boot_failures                                   | 1          | 8          |
| BUG:kernel_reboot-without-warning_in_test_stage | 1          |            |
| BUG:stack_guard_page_was_hit_at#(stack_is#..#)  | 0          | 8          |
| RIP:page_fault                                  | 0          | 8          |
| Kernel_panic-not_syncing:Fatal_exception        | 0          | 8          |
+-------------------------------------------------+------------+------------+



[  121.844427] perf: interrupt took too long (3955 > 3947), lowering kernel.perf_event_max_sample_rate to 50000
[  122.080152] perf: interrupt took too long (4947 > 4943), lowering kernel.perf_event_max_sample_rate to 40000
[  122.724744] perf: interrupt took too long (6201 > 6183), lowering kernel.perf_event_max_sample_rate to 32000
[  211.978530] BUG: stack guard page was hit at ffffc90001773fe8 (stack is ffffc90001774000..ffffc90001777fff)
[  211.989358] kernel stack overflow (double-fault): 0000 [#1] SMP
[  211.996320] Modules linked in: rpcsec_gss_krb5 auth_rpcgss nfsv4 dns_resolver netconsole sr_mod cdrom sg intel_rapl ahci snd_hda_codec_realtek x86_pkg_temp_thermal intel_powerclamp snd_hda_codec_generic libahci coretemp ppdev i915 snd_hda_intel drm_kms_helper syscopyarea sysfillrect sysimgblt snd_hda_codec fb_sys_fops kvm snd_hda_core irqbypass snd_hwdep crct10dif_pclmul snd_pcm crc32_pclmul pcspkr crc32c_intel ghash_clmulni_intel cryptd snd_timer serio_raw snd libata soundcore drm shpchp wmi parport_pc parport video ip_tables
[  212.049322] CPU: 2 PID: 718 Comm: singleuser Not tainted 4.9.0-00014-g39cd5a4 #1
[  212.057720] Hardware name: Hewlett-Packard HP Pro 3340 MT/17A1, BIOS 8.07 01/24/2013
[  212.066473] task: ffff88011b6a4b80 task.stack: ffffc90001774000
[  212.073399] RIP: 0010:[<ffffffff81957cad>]  [<ffffffff81957cad>] page_fault+0xd/0x30
[  212.082139] RSP: 0018:ffffc90001773ff8  EFLAGS: 00010083
[  212.088404] RAX: 000000000000d2c0 RBX: ffffc900017740e8 RCX: ffffffff81957217
[  212.096507] RDX: 000000000000d2c0 RSI: 0000000000000000 RDI: ffffc900017740e8
[  212.104587] RBP: ffffc900017740d8 R08: ffff88011b6a4b80 R09: 0000000000000004
[  212.112664] R10: ffff88011fdce000 R11: 0000000000000000 R12: 0000000000000000
[  212.120702] R13: 0000000000000000 R14: 0000000000000000 R15: 0000000001200011
[  212.128746] FS:  00007fea1ae04700(0000) GS:ffff88011fb00000(0000) knlGS:ffff88011fb00000
[  212.137744] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  212.144334] CR2: ffffc90001773fe8 CR3: 0000000116f09000 CR4: 00000000001506e0
[  212.152348] Stack:
[  212.155208] Call Trace:
[  212.158478]  [<ffffffff81067f86>] ? __do_page_fault+0x6/0x4d0
[  212.165081]  [<ffffffff81068480>] ? do_page_fault+0x30/0x80
[  212.171484]  [<ffffffff81957cc8>] ? page_fault+0x28/0x30


To reproduce:

        git clone git://git.kernel.org/pub/scm/linux/kernel/git/wfg/lkp-tests.git
        cd lkp-tests
        bin/lkp install job.yaml  # job file is attached in this email
        bin/lkp run     job.yaml



Thanks,
Kernel Test Robot