Greeting,

FYI, we noticed the following commit (built with gcc-9):

commit: 4092a9304d1dd88368c7cd327adb666f70a46519 ("[PATCH] __register_sysctl_table: do not drop subdir")
url: https://github.com/0day-ci/linux/commits/Boris-Sukholitko/__register_sysctl_table-do-not-drop-subdir/20200527-185030


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 16G

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


+-----------------------------------------------------+------------+------------+
|                                                     | 444fc5cde6 | 4092a9304d |
+-----------------------------------------------------+------------+------------+
| boot_successes                                      | 7          | 12         |
| boot_failures                                       | 0          | 21         |
| WARNING:at_fs/proc/proc_sysctl.c:#retire_sysctl_set | 0          | 21         |
| RIP:retire_sysctl_set                               | 0          | 21         |
+-----------------------------------------------------+------------+------------+


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


[   17.566582] WARNING: CPU: 1 PID: 30 at fs/proc/proc_sysctl.c:1683 retire_sysctl_set+0xf/0x12
[   17.569242] Modules linked in: hidp cmtp kernelcapi bnep rfcomm bluetooth ecdh_generic ecc rfkill can_bcm can_raw can pptp gre l2tp_ppp l2tp_netlink l2tp_core ip6_udp_tunnel udp_tunnel pppoe pppox ppp_generic slhc crypto_user ib_core nfnetlink scsi_transport_iscsi dccp_ipv6 atm sctp libcrc32c dccp_ipv4 dccp sr_mod cdrom ata_generic pata_acpi bochs_drm drm_vram_helper drm_ttm_helper ttm ppdev parport_pc joydev floppy parport ata_piix drm_kms_helper syscopyarea sysfillrect sysimgblt fb_sys_fops libata drm i2c_piix4
[   17.588023] CPU: 1 PID: 30 Comm: kworker/u4:1 Not tainted 5.7.0-rc7-00009-g4092a9304d1dd #1
[   17.590914] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-1 04/01/2014
[   17.593792] Workqueue: netns cleanup_net
[   17.596063] RIP: 0010:retire_sysctl_set+0xf/0x12
[   17.598264] Code: 00 00 00 00 49 c7 40 48 00 00 00 00 49 c7 40 50 00 00 00 00 c3 66 0f 1f 44 00 00 66 66 66 66 90 48 8b 47 58 48 85 c0 75 01 c3 <0f> 0b c3 66 66 66 66 90 55 48 89 e5 48 83 ec 60 48 89 4c 24 48 48
[   17.605164] RSP: 0018:ffffaf6e80107df8 EFLAGS: 00010282
[   17.607844] RAX: ffff8c679b4e3458 RBX: ffff8c679b678000 RCX: 0000000080150011
[   17.610770] RDX: ffff8c679b678030 RSI: ffffffffa420b4c8 RDI: ffff8c679b6780b0
[   17.614024] RBP: ffffaf6e80107e30 R08: 0000000000000000 R09: ffffffffa2d82300
[   17.617120] R10: ffff8c67a1651cc0 R11: 0000000000000001 R12: ffffffffa420b4c0
[   17.620012] R13: ffffffffa420b4c8 R14: ffffaf6e80107e30 R15: ffff8c67a1430060
[   17.622807] FS:  0000000000000000(0000) GS:ffff8c67ffd00000(0000) knlGS:0000000000000000
[   17.625994] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   17.628799] CR2: 0000000002d2f830 CR3: 00000003964cc000 CR4: 00000000000406e0
[   17.632376] Call Trace:
[   17.634848]  ops_exit_list+0x36/0x70
[   17.637279]  cleanup_net+0x236/0x360
[   17.639545]  process_one_work+0x1bb/0x3b0
[   17.641937]  worker_thread+0x50/0x3e0
[   17.644359]  kthread+0x111/0x150
[   17.646661]  ? process_one_work+0x3b0/0x3b0
[   17.649433]  ? kthread_park+0x90/0x90
[   17.652014]  ret_from_fork+0x35/0x40
[   17.655589] ---[ end trace 275a12e471dacce7 ]---


To reproduce:

        # build kernel
	cd linux
	cp config-5.7.0-rc7-00009-g4092a9304d1dd .config
	make HOSTCC=gcc-9 CC=gcc-9 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