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

commit: 5149a783b9655eb96bf418cf12a3d7786558df45 ("[RFC PATCH 2/2] selinux: Propagate RCU walk status from 'security_inode_follow_link()'")
url: https://github.com/0day-ci/linux/commits/Will-Deacon/selinux-Don-t-call-avc_compute_av-from-RCU-path-walk/20191122-104223


in testcase: boot

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):


+----------------------------------------------------------------------------+------------+------------+
|                                                                            | c7e8a6ea45 | 5149a783b9 |
+----------------------------------------------------------------------------+------------+------------+
| boot_successes                                                             | 4          | 0          |
| boot_failures                                                              | 0          | 13         |
| WARNING:at_security/selinux/avc.c:#avc_has_perm_flags                      | 0          | 13         |
| RIP:avc_has_perm_flags                                                     | 0          | 13         |
| Kernel_panic-not_syncing:VFS:Unable_to_mount_root_fs_on_unknown-block(#,#) | 0          | 13         |
+----------------------------------------------------------------------------+------------+------------+


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


[    4.885585] WARNING: CPU: 1 PID: 133 at security/selinux/avc.c:1156 avc_has_perm_flags+0x152/0x1f0
[    4.885585] Modules linked in:
[    4.885585] CPU: 1 PID: 133 Comm: kworker/u4:0 Not tainted 5.4.0-rc8-00017-g5149a783b9655 #1
[    4.885585] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1 04/01/2014
[    4.885585] RIP: 0010:avc_has_perm_flags+0x152/0x1f0
[    4.885585] Code: 04 75 aa 4c 8d 4c 24 20 4c 8d 44 24 0c 44 89 e1 44 89 ea 89 de 4c 89 f7 4c 89 1c 24 e8 f7 f0 ff ff 4c 8b 1c 24 e9 75 ff ff ff <0f> 0b b8 f3 ff ff ff eb a0 31 c0 44 8b 4c 24 14 41 21 d1 eb 8b 48
[    4.885585] RSP: 0000:ffffb1fb4010fb00 EFLAGS: 00010246
[    4.885585] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 000000000000000a
[    4.885585] RDX: 0000000000000003 RSI: 0000000000000001 RDI: ffffffffb9d30620
[    4.885585] RBP: 0000000000000001 R08: 0000000000000000 R09: 0000000000000002
[    4.885585] R10: 0000000000000001 R11: ffffb1fb4010fba0 R12: ffff8c792a0e14d0
[    4.885585] R13: ffff8c792a08da80 R14: ffffb1fb4010fd68 R15: ffff8c792a0e14d0
[    4.885585] FS:  0000000000000000(0000) GS:ffff8c793fd00000(0000) knlGS:0000000000000000
[    4.885585] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[    4.885585] CR2: 00000000ffffffff CR3: 00000001e240a000 CR4: 00000000000406e0
[    4.885585] Call Trace:
[    4.885585]  ? lookup_fast+0xc8/0x2b0
[    4.885585]  ? _cond_resched+0x19/0x30
[    4.885585]  selinux_inode_follow_link+0x84/0xb0
[    4.885585]  security_inode_follow_link+0x37/0x50
[    4.885585]  trailing_symlink+0xb7/0x260
[    4.885585]  path_openat+0xc6/0x1550
[    4.885585]  do_filp_open+0x9b/0x110
[    4.885585]  ? do_open_execat+0x83/0x1a0
[    4.885585]  do_open_execat+0x83/0x1a0
[    4.885585]  __do_execve_file+0x623/0x930
[    4.885585]  ? _cond_resched+0x19/0x30
[    4.885585]  ? yield_to+0x1c0/0x1c0
[    4.885585]  do_execve+0x21/0x30
[    4.885585]  call_usermodehelper_exec_async+0x19a/0x1b0
[    4.885585]  ? recalc_sigpending+0x17/0x50
[    4.885585]  ? call_usermodehelper+0xa0/0xa0
[    4.885585]  ret_from_fork+0x35/0x40
[    4.885585] ---[ end trace b767db40447c2290 ]---


To reproduce:

        # build kernel
	cd linux
	cp config-5.4.0-rc8-00017-g5149a783b9655 .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,
lkp