[LTP] [PATCH] proc_sysctl: Fix up ->is_seen() handling

[kernel test robot]

Hello,

kernel test robot noticed "segfault_at_ip_sp_error" on:

commit: 981dfb28e2d5851435754da557baadfdcbc828a8 ("[PATCH] proc_sysctl: Fix up ->is_seen() handling")
url: https://github.com/intel-lab-lkp/linux/commits/NeilBrown/proc_sysctl-Fix-up-is_seen-handling/20250613-083900
base: https://git.kernel.org/cgit/linux/kernel/git/sysctl/sysctl.git sysctl-next
patch link: https://lore.kernel.org/all/174977507817.608730.3467596162021780258@noble.neil.brown.name/
patch subject: [PATCH] proc_sysctl: Fix up ->is_seen() handling

in testcase: ltp
version: ltp-x86_64-99ebf35b3-1_20250607
with following parameters:

	test: net.tirpc_tests



config: x86_64-rhel-9.4-ltp
compiler: gcc-12
test machine: 8 threads 1 sockets Intel(R) Core(TM) i7-3770K CPU @ 3.50GHz (Ivy Bridge) with 16G memory

(please refer to attached dmesg/kmsg for entire log/backtrace)



If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <oliver.sang@intel.com>
| Closes: https://lore.kernel.org/oe-lkp/202506161619.6738c86c-lkp@intel.com


kern  :info  : [  157.002007] tirpc_clnt_cont[10507]: segfault at 8 ip 000055c92e030119 sp 00007ffd50302fb0 error 4 in tirpc_clnt_control[1119,55c92e030000+1000] likely on CPU 2 (core 2, socket 0)
kern :info : [ 157.002435] Code: 1d 0f 00 00 31 db 48 89 c1 4c 8d 44 24 10 ba 01 00 00 00 0f 29 44 24 10 e8 44 ff ff ff 48 8d 54 24 0c be 06 00 00 00 48 89 c7 <48> 8b 40 08 ff 50 28 48 8d 35 e3 0e 00 00 bf 01 00 00 00 83 f8 01
All code
========
   0:	1d 0f 00 00 31       	sbb    $0x3100000f,%eax
   5:	db 48 89             	fisttpl -0x77(%rax)
   8:	c1 4c 8d 44 24       	rorl   $0x24,0x44(%rbp,%rcx,4)
   d:	10 ba 01 00 00 00    	adc    %bh,0x1(%rdx)
  13:	0f 29 44 24 10       	movaps %xmm0,0x10(%rsp)
  18:	e8 44 ff ff ff       	call   0xffffffffffffff61
  1d:	48 8d 54 24 0c       	lea    0xc(%rsp),%rdx
  22:	be 06 00 00 00       	mov    $0x6,%esi
  27:	48 89 c7             	mov    %rax,%rdi
  2a:*	48 8b 40 08          	mov    0x8(%rax),%rax		<-- trapping instruction
  2e:	ff 50 28             	call   *0x28(%rax)
  31:	48 8d 35 e3 0e 00 00 	lea    0xee3(%rip),%rsi        # 0xf1b
  38:	bf 01 00 00 00       	mov    $0x1,%edi
  3d:	83 f8 01             	cmp    $0x1,%eax

Code starting with the faulting instruction
===========================================
   0:	48 8b 40 08          	mov    0x8(%rax),%rax
   4:	ff 50 28             	call   *0x28(%rax)
   7:	48 8d 35 e3 0e 00 00 	lea    0xee3(%rip),%rsi        # 0xef1
   e:	bf 01 00 00 00       	mov    $0x1,%edi
  13:	83 f8 01             	cmp    $0x1,%eax
user  :warn  : [  157.168019] LTP: starting tirpc_rpc_reg (rpc_test.sh -c tirpc_rpc_reg)
user  :warn  : [  158.080633] LTP: starting tirpc_rpc_call (rpc_test.sh -s tirpc_svc_1 -c tirpc_rpc_call)
user  :warn  : [  159.209909] LTP: starting tirpc_rpc_broadcast (rpc_test.sh -s tirpc_svc_1 -c tirpc_rpc_broadcast)
user  :warn  : [  160.241552] LTP: starting tirpc_rpc_broadcast_exp (rpc_test.sh -s tirpc_svc_1 -c tirpc_rpc_broadcast_exp -e "1,2")
user  :warn  : [  161.182028] LTP: starting tirpc_clnt_create (rpc_test.sh -s tirpc_svc_2 -c tirpc_clnt_create)
user  :warn  : [  162.081857] LTP: starting tirpc_clnt_create_timed (rpc_test.sh -s tirpc_svc_2 -c tirpc_clnt_create_timed)
user  :warn  : [  163.234462] LTP: starting tirpc_svc_create (rpc_test.sh -c tirpc_svc_create)
user  :notice: [  163.507518] Gnu C                  gcc (Debian 12.2.0-14+deb12u1) 12.2.0

user  :notice: [  163.508419] Clang

user  :notice: [  163.509434] Gnu make               4.3

user  :notice: [  163.510405] util-linux             2.38.1

user  :warn  : [  164.010443] LTP: starting tirpc_toplevel_clnt_call (rpc_test.sh -s tirpc_svc_2 -c tirpc_toplevel_clnt_call)
user  :warn  : [  165.054172] LTP: starting tirpc_clnt_destroy (rpc_test.sh -s tirpc_svc_2 -c tirpc_clnt_destroy)
user  :warn  : [  166.170592] LTP: starting tirpc_svc_destroy (rpc_test.sh -c tirpc_svc_destroy)
user  :err   : [  166.988060] -------------------------------------------



The kernel config and materials to reproduce are available at:
https://download.01.org/0day-ci/archive/20250616/202506161619.6738c86c-lkp@intel.com



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https://github.com/intel/lkp-tests/wiki