FYI, we noticed the following commit (built with gcc-6):

commit: 0dd4eca846629b5dc7d11ca40ae2a1379334b9e4 ("kernfs, sysfs, cgroup, intel_rdt: Support fs_context")
https://git.kernel.org/cgit/linux/kernel/git/dhowells/linux-fs.git mount-context

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 -m 256M

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


+------------------------------------------+------------+------------+
|                                          | 76224b97f0 | 0dd4eca846 |
+------------------------------------------+------------+------------+
| boot_successes                           | 8          | 2          |
| boot_failures                            | 0          | 4          |
| kernel_BUG_at_fs/super.c                 | 0          | 4          |
| invalid_opcode:#[##]                     | 0          | 4          |
| EIP:vfs_get_tree                         | 0          | 4          |
| Kernel_panic-not_syncing:Fatal_exception | 0          | 4          |
+------------------------------------------+------------+------------+



[    7.295290] kernel BUG at fs/super.c:1775!
[    7.297885] invalid opcode: 0000 [#1] PREEMPT SMP
[    7.303028] CPU: 0 PID: 1 Comm: init Not tainted 4.17.0-rc5-00204-g0dd4eca #54
[    7.311821] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1 04/01/2014
[    7.322843] EIP: vfs_get_tree+0x16d/0x170
[    7.326346] EFLAGS: 00010246 CPU: 0
[    7.327808] EAX: 00000030 EBX: ce1a19c0 ECX: 00000000 EDX: ce1a19c0
[    7.330450] ESI: ce1a19c0 EDI: 00000000 EBP: c7de1f04 ESP: c7de1eec
[    7.336866]  DS: 007b ES: 007b FS: 00d8 GS: 00e0 SS: 0068
[    7.341293] CR0: 80050033 CR2: b7f3f588 CR3: 0bab1000 CR4: 00000690
[    7.346567] Call Trace:
[    7.349189]  ? vfs_set_fs_source+0x70/0x70
[    7.350853]  ? vfs_set_fs_source+0x70/0x70
[    7.352936]  do_mount+0x21a/0xaa0
[    7.355547]  ksys_mount+0xc4/0x140
[    7.359244]  sys_mount+0x19/0x20
[    7.362170]  do_int80_syscall_32+0x76/0x190
[    7.367179]  entry_INT80_32+0x36/0x36
[    7.371221] EIP: 0xb7f36c3e
[    7.375471] EFLAGS: 00000296 CPU: 0
[    7.378821] EAX: ffffffda EBX: 0804a3a9 ECX: 0804a3a1 EDX: 0804a3a9
[    7.381308] ESI: 0000000e EDI: 00000000 EBP: bfc00db8 ESP: bfc00d1c
[    7.383960]  DS: 007b ES: 007b FS: 0000 GS: 0033 SS: 007b
[    7.388781] Code: c7 43 0c 00 00 00 00 e8 b2 e2 ff ff b8 f4 ff ff ff eb 8f 8d 76 00 b8 fe ff ff ff c3 8b 43 04 ff 30 68 e8 7d ec c1 e8 d4 b1 f0 ff <0f> 0b 90 55 89 c8 89 e5 5d c3 89 f6 8d bc 27 00 00 00 00 55 31 
[    7.408953] EIP: vfs_get_tree+0x16d/0x170 SS:ESP: 0068:c7de1eec
[    7.420191] ---[ end trace 2ff80a4e86e2d2e8 ]---


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