FYI, we noticed the following commit (built with gcc-5):

commit: c77d419f9248f8c40bbf773d59aa5b6cbc0d60f0 ("[patch V2 07/10] x86/mm/cpa: Add sanity check for existing mappings")
url: https://github.com/0day-ci/linux/commits/Thomas-Gleixner/x86-mm-cpa-Improve-large-page-preservation-handling/20180915-062636


in testcase: trinity
with following parameters:

	runtime: 300s

test-description: Trinity is a linux system call fuzz tester.
test-url: http://codemonkey.org.uk/projects/trinity/


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

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


+---------------------------------------------------------------+------------+------------+
|                                                               | 03ae905b93 | c77d419f92 |
+---------------------------------------------------------------+------------+------------+
| boot_successes                                                | 35         | 0          |
| boot_failures                                                 | 1          | 7          |
| Mem-Info                                                      | 1          |            |
| WARNING:at_arch/x86/mm/pageattr.c:#__change_page_attr_set_clr | 0          | 7          |
| EIP:__change_page_attr_set_clr                                | 0          | 7          |
+---------------------------------------------------------------+------------+------------+



[    5.168861] WARNING: CPU: 0 PID: 1 at arch/x86/mm/pageattr.c:829 __change_page_attr_set_clr+0x324/0x7b8
[    5.170140] Modules linked in:
[    5.170503] CPU: 0 PID: 1 Comm: swapper Not tainted 4.19.0-rc2-00018-gc77d419 #2
[    5.171321] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1 04/01/2014
[    5.172255] EIP: __change_page_attr_set_clr+0x324/0x7b8
[    5.172846] Code: 75 b8 ff 75 bc 8b 45 b0 8b 7d ac c1 e0 0c 8d 44 07 ff 50 ff 75 ac 68 ce e7 83 79 68 01 68 83 79 68 e0 e7 83 79 e8 bb 03 04 00 <0f> 0b 80 4b 1c 02 83 c4 20 be 01 00 00 00 e9 9b 00 00 00 89 f0 89
[    5.174915] EAX: 00000077 EBX: 85833f24 ECX: 00000006 EDX: 00000003
[    5.175619] ESI: 000001e1 EDI: 79800000 EBP: 85833f04 ESP: 85833e68
[    5.176311] DS: 007b ES: 007b FS: 0000 GS: 0000 SS: 0068 EFLAGS: 00010202
[    5.177074] CR0: 80050033 CR2: 080c2008 CR3: 01ad5000 CR4: 000406d0
[    5.177783] Call Trace:
[    5.178071]  ? mutex_unlock+0xb/0xd
[    5.178498]  ? vm_unmap_aliases+0x160/0x168
[    5.178966]  change_page_attr_set_clr+0x101/0x29c
[    5.179497]  ? preempt_count_add+0x5b/0x8c
[    5.179953]  set_memory_ro+0x19/0x1b
[    5.180356]  set_pages_ro+0x14/0x16
[    5.180757]  mark_rodata_ro+0x73/0xa5
[    5.181167]  ? rest_init+0x1e2/0x1e2
[    5.181576]  kernel_init+0x25/0xd5
[    5.181955]  ret_from_fork+0x19/0x30
[    5.182355] irq event stamp: 2163908
[    5.182763] hardirqs last  enabled at (2163907): [<79064c74>] console_unlock+0x401/0x44c
[    5.183649] hardirqs last disabled at (2163908): [<79000fbe>] trace_hardirqs_off_thunk+0xc/0x10
[    5.184606] softirqs last  enabled at (2163904): [<795e0462>] __do_softirq+0x272/0x31a
[    5.185485] softirqs last disabled at (2163815): [<7900da03>] do_softirq_own_stack+0x26/0x2c
[    5.186397] ---[ end trace e9f576b73c312d83 ]---


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,
lkp