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

commit: 58604f33501dee9e277d5be38d619a24088d91e2 ("page cache: Convert delete_batch to XArray")
git://git.infradead.org/users/willy/linux-dax.git xarray-2017-12-04

in testcase: pft
with following parameters:

	iterations: 20x

test-description: Pft is the page fault test micro benchmark.
test-url: https://github.com/gormanm/pft


on test machine: qemu-system-x86_64 -enable-kvm -cpu kvm64,+ssse3 -m 1G

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


+------------------------------------------------------+------------+------------+
|                                                      | e2677e8adb | 58604f3350 |
+------------------------------------------------------+------------+------------+
| boot_successes                                       | 9          | 2          |
| boot_failures                                        | 0          | 4          |
| WARNING:at_mm/truncate.c:#truncate_inode_pages_range | 0          | 4          |
| RIP:truncate_inode_pages_range                       | 0          | 4          |
+------------------------------------------------------+------------+------------+



[   38.690816] WARNING: CPU: 0 PID: 1 at mm/truncate.c:453 truncate_inode_pages_range+0xbe0/0xd0e
[   38.692065] Modules linked in:
[   38.692065] CPU: 0 PID: 1 Comm: swapper Not tainted 4.15.0-rc2-00039-g58604f3 #2
[   38.692065] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1 04/01/2014
[   38.692065] task: 000000005507d1e2 task.stack: 000000005d472ef5
[   38.692065] RIP: 0010:truncate_inode_pages_range+0xbe0/0xd0e
[   38.692065] RSP: 0000:ffffc9000000b788 EFLAGS: 00010202
[   38.692065] RAX: 0000000000000003 RBX: ffffffffffffffff RCX: 0000000000000000
[   38.692065] RDX: 0000000000000000 RSI: 0000000000000001 RDI: ffffffffa9515f48
[   38.692065] RBP: ffffc9000000b950 R08: 0000000000000000 R09: 0000000000000000
[   38.692065] R10: 0000000000000000 R11: ffffc9000000b718 R12: 0000000000000010
[   38.692065] R13: ffff880030738d80 R14: 0000000000000000 R15: 0000000000000001
[   38.692065] FS:  0000000000000000(0000) GS:ffffffffa944a000(0000) knlGS:0000000000000000
[   38.692065] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   38.692065] CR2: 0000000000000000 CR3: 000000000d639000 CR4: 00000000000006b0
[   38.692065] Call Trace:
[   38.692065]  truncate_inode_pages_range+0x37/0x3a
[   38.692065]  truncate_inode_pages+0x12/0x14
[   38.692065]  truncate_pagecache+0x40/0x59
[   38.692065]  truncate_setsize+0x46/0x4b
[   38.692065]  simple_setattr+0x5c/0x7e
[   38.692065]  notify_change+0x4d1/0x680
[   38.692065]  do_truncate+0xcd/0xfe
[   38.692065]  do_last+0xabb/0xbd4
[   38.692065]  path_openat+0x33c/0x48e
[   38.692065]  ? error+0x32/0x32
[   38.692065]  do_filp_open+0x60/0x13a
[   38.692065]  ? mntput_no_expire+0x53/0x2bc
[   38.692065]  ? do_raw_spin_unlock+0x10a/0x140
[   38.692065]  ? _raw_spin_unlock+0xe/0x16
[   38.692065]  do_sys_open+0x2ad/0x38f
[   38.692065]  ? do_sys_open+0x2ad/0x38f
[   38.692065]  ? error+0x32/0x32
[   38.692065]  SyS_open+0x1e/0x20
[   38.692065]  do_name+0x115/0x363
[   38.692065]  write_buffer+0x28/0x39
[   38.692065]  flush_buffer+0x53/0xd2
[   38.692065]  __gunzip+0x3b9/0x4d1
[   38.692065]  ? bunzip2+0x5f6/0x5f6
[   38.692065]  ? do_early_param+0xc0/0xc0
[   38.692065]  gunzip+0x11/0x13
[   38.692065]  ? do_start+0x23/0x23
[   38.692065]  unpack_to_rootfs+0x1b5/0x352
[   38.692065]  ? do_start+0x23/0x23
[   38.692065]  ? unpack_to_rootfs+0x352/0x352
[   38.692065]  populate_rootfs+0x8b/0x1a0
[   38.692065]  ? unpack_to_rootfs+0x352/0x352
[   38.692065]  do_one_initcall+0xb2/0x1cf
[   38.692065]  ? do_early_param+0x3f/0xc0
[   38.692065]  kernel_init_freeable+0x122/0x1e8
[   38.692065]  ? rest_init+0xaf/0xaf
[   38.692065]  kernel_init+0xe/0x160
[   38.692065]  ret_from_fork+0x24/0x30
[   38.692065] Code: 31 c9 31 d2 45 0f b6 ff 44 89 fe e8 86 59 f9 ff 4c 8b 8d 48 fe ff ff 49 63 c7 48 83 c0 02 48 ff 04 c5 98 fd 62 a9 4d 39 cc 74 02 <0f> ff 31 c9 31 d2 44 89 fe 48 c7 c7 18 5f 51 a9 e8 56 59 f9 ff 
[   38.692065] ---[ end trace 60394982e4827c89 ]---


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