FYI, we noticed the following commit (built with gcc-7):

commit: f675f2f91d0457e2b430936f0d756457fdcad1ca ("[PATCH V2 1/3] mm/debug: Add tests validating arch page table helpers for core features")
url: https://github.com/0day-ci/linux/commits/Anshuman-Khandual/mm-debug-Add-more-arch-page-table-helper-tests/20200324-161233


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-x86_64 -enable-kvm -cpu SandyBridge -smp 2 -m 8G

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


+-------------------------------------------------------------------------------+---------------+------------+
|                                                                               | next-20200323 | f675f2f91d |
+-------------------------------------------------------------------------------+---------------+------------+
| boot_successes                                                                | 1             | 0          |
| boot_failures                                                                 | 3             | 4          |
| WARNING:suspicious_RCU_usage                                                  | 3             | 4          |
| drivers/char/ipmi/ipmi_msghandler.c:#RCU-list_traversed_in_non-reader_section | 3             | 4          |
| net/ipv4/fib_trie.c:#RCU-list_traversed_in_non-reader_section                 | 3             | 2          |
| WARNING:at_mm/debug_vm_pgtable.c:#debug_vm_pgtable                            | 0             | 4          |
| RIP:debug_vm_pgtable                                                          | 0             | 4          |
| calltrace:hrtimers_dead_cpu                                                   | 0             | 1          |
| calltrace:irq_exit                                                            | 0             | 3          |
+-------------------------------------------------------------------------------+---------------+------------+


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


[  283.486118] WARNING: CPU: 1 PID: 1 at mm/debug_vm_pgtable.c:371 debug_vm_pgtable+0x4dc/0x7e3
[  283.487342] Modules linked in:
[  283.487752] CPU: 1 PID: 1 Comm: swapper/0 Not tainted 5.6.0-rc7-next-20200323-00001-gf675f2f91d045 #1
[  283.488817] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-1 04/01/2014
[  283.489794] RIP: 0010:debug_vm_pgtable+0x4dc/0x7e3
[  283.490361] Code: b5 fd 48 8b 7d d0 be 20 01 00 00 e8 3d 9f b5 fd 48 8b 75 c8 48 8b 7d d0 e8 30 9f b5 fd 48 8b 75 c8 48 8b 7d d0 e8 23 9f b5 fd <0f> 0b 48 8b 75 c8 48 8b 7d d0 e8 14 9f b5 fd 0f 0b 48 8b 75 c8 48
[  283.492577] RSP: 0000:ffff888236493ed8 EFLAGS: 00010202
[  283.493235] RAX: 00000001e1d31025 RBX: ffff88823e7f6cd8 RCX: ffffffffffffffff
[  283.494135] RDX: 0000000000000000 RSI: 0000000000000025 RDI: 00000001e1d31000
[  283.495002] RBP: ffff888236493f38 R08: 0000000000000001 R09: 0000000000000001
[  283.495858] R10: 0000000000000001 R11: 0000000000000000 R12: ffff88821d907000
[  283.496748] R13: ffff88821d8fc498 R14: ffff88821d8fda90 R15: ffff88821d8fc000
[  283.497614] FS:  0000000000000000(0000) GS:ffff888237800000(0000) knlGS:0000000000000000
[  283.498585] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  283.499290] CR2: 00000000ffffffff CR3: 00000001e1222000 CR4: 00000000000406e0
[  283.500165] Call Trace:
[  283.500499]  ? rest_init+0x240/0x240
[  283.500985]  kernel_init+0x13/0x110
[  283.501433]  ret_from_fork+0x24/0x30
[  283.501907] irq event stamp: 4760776
[  283.502366] hardirqs last  enabled at (4760775): [<ffffffffb481e34d>] _raw_spin_unlock_irqrestore+0x4d/0x60
[  283.511686] hardirqs last disabled at (4760776): [<ffffffffb3c038d4>] trace_hardirqs_off_thunk+0x1a/0x1c
[  283.512914] softirqs last  enabled at (4760748): [<ffffffffb4c002cf>] __do_softirq+0x2cf/0x4ad
[  283.514086] softirqs last disabled at (4760741): [<ffffffffb3cf4f4d>] irq_exit+0xcd/0xe0
[  283.515114] ---[ end trace 7e3383c4261f8faa ]---


To reproduce:

        # build kernel
	cd linux
	cp config-5.6.0-rc7-next-20200323-00001-gf675f2f91d045 .config
	make HOSTCC=gcc-7 CC=gcc-7 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,
Rong Chen