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