FYI, we noticed the following commit (built with gcc-4.9):

commit: 51bad67ffbce0aaa44579f84ef5d05597054ec6a ("x86/asm: Pad assembly functions with INT3 instructions")
https://git.kernel.org/cgit/linux/kernel/git/tip/tip.git x86/pti

in testcase: boot

on test machine: qemu-system-i386 -enable-kvm -m 256M

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


+-------------------------------------------+------------+------------+
|                                           | e0f6d1a526 | 51bad67ffb |
+-------------------------------------------+------------+------------+
| boot_successes                            | 0          | 0          |
| boot_failures                             | 24         | 24         |
| WARNING:at_kernel/kthread.c:#kthread_park | 24         | 24         |
| EIP:kthread_park                          | 24         | 24         |
| int3:#[##]                                | 0          | 24         |
| EIP:ret_from_intr                         | 0          | 24         |
| Kernel_panic-not_syncing:Fatal_exception  | 0          | 24         |
+-------------------------------------------+------------+------------+




[   11.174401] Write protecting the kernel text: 7192k
[   11.174882] Write protecting the kernel read-only data: 2796k
[   11.175437] rodata_test: all tests were successful
[   11.176131] random: get_random_u32 called from arch_rnd+0x1e/0x40 with crng_init=0
[   11.176836] random: get_random_u32 called from load_elf_binary+0x32d/0x12c4 with crng_init=0
[   11.177719] int3: 0000 [#1] PREEMPT DEBUG_PAGEALLOC
[   11.178183] Modules linked in:
[   11.178501] CPU: 0 PID: 1 Comm: init Tainted: G        W         4.17.0-rc3-00048-g51bad67 #2
[   11.179288] EIP: ret_from_intr+0xd/0x14
[   11.179647] EFLAGS: 00000046 CPU: 0
[   11.179975] EAX: 00000003 EBX: 00000000 ECX: 00000000 EDX: 00000000
[   11.180553] ESI: 00000000 EDI: 79048b50 EBP: 0603bfb4 ESP: 8603bfb4
[   11.181188]  DS: 007b ES: 007b FS: 0000 GS: 00e0 SS: 0068
[   11.181675] CR0: 80050033 CR2: 6ffce1bf CR3: 0b2c9000 CR4: 00000690
[   11.182269] Call Trace:
[   11.182501] Code: 00 00 00 eb e6 cc cc cc cc cc cc cc cc cc cc cc cc cc fa 8d b6 00 00 00 00 e8 5d e8 8f ff 8b 44 24 34 83 e0 03 83 f8 03 72 28 cc <cc> cc cc cc cc cc cc fa 8d b6 00 00 00 00 e8 3d e8 8f ff 89 e0 
[   11.184326] EIP: ret_from_intr+0xd/0x14 SS:ESP: 0068:8603bfb4
[   11.184848] ---[ end trace 031a6bca415900de ]---
[   11.185302] Kernel panic - not syncing: Fatal exception
[   11.185782] Kernel Offset: disabled

Elapsed time: 20

#!/bin/bash


To reproduce:

        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,
Xiaolong