Hello,

kernel test robot noticed "BUG:unable_to_handle_page_fault_for_address" on:

commit: 747e356babd8bdd569320c29916470345afd3cf7 ("[PATCH v3 5/6] VFS: rename 
kern_path_locked() and related functions.")
url: 
https://github.com/intel-lab-lkp/linux/commits/NeilBrown/VFS-ovl-add-lookup_one_positive_killable/20250915-101929
base: https://git.kernel.org/cgit/linux/kernel/git/vfs/vfs.git vfs.all
patch link: 
https://lore.kernel.org/all/[email protected]/
patch subject: [PATCH v3 5/6] VFS: rename kern_path_locked() and related 
functions.

in testcase: boot

config: i386-randconfig-2006-20250825
compiler: gcc-14
test machine: qemu-system-i386 -enable-kvm -cpu SandyBridge -smp 2 -m 4G

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


+---------------------------------------------+------------+------------+
|                                             | 1c87fa0646 | 747e356bab |
+---------------------------------------------+------------+------------+
| boot_successes                              | 24         | 0          |
| boot_failures                               | 0          | 24         |
| BUG:unable_to_handle_page_fault_for_address | 0          | 24         |
| Oops:Oops:#[##]                             | 0          | 24         |
| EIP:mnt_want_write                          | 0          | 24         |
| Kernel_panic-not_syncing:Fatal_exception    | 0          | 24         |
+---------------------------------------------+------------+------------+


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 <[email protected]>
| Closes: https://lore.kernel.org/oe-lkp/[email protected]


[   12.277015][   T18] BUG: unable to handle page fault for address: fefeff02
[   12.278063][   T18] #PF: supervisor read access in kernel mode
[   12.278982][   T18] #PF: error_code(0x0000) - not-present page
[   12.279886][   T18] *pde = 00000000
[   12.280491][   T18] Oops: Oops: 0000 [#1]
[   12.281158][   T18] CPU: 0 UID: 0 PID: 18 Comm: kdevtmpfs Not tainted 
6.17.0-rc3-00100-g747e356babd8 #1 PREEMPT(full)  
97a7d9f1f9975edf00ea02f43ed800cec17522a0
[   12.283292][   T18] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), 
BIOS 1.16.3-debian-1.16.3-2 04/01/2014
[ 12.283887][ T18] EIP: mnt_want_write (include/linux/fs.h:1908 
include/linux/fs.h:2044 fs/namespace.c:566) 
[ 12.283887][ T18] Code: 74 26 00 55 83 e8 30 89 e5 e8 b0 ff ff ff 5d c3 2e 8d 
b4 26 00 00 00 00 8d b6 00 00 00 00 3e 8d 74 26 00 55 89 e5 56 53 89 c3 <8b> 40 
04 05 d8 01 00 00 e8 67 f5 ff ff 89 d8 e8 90 e6 ff ff 89 c6
All code
========
   0:   74 26                   je     0x28
   2:   00 55 83                add    %dl,-0x7d(%rbp)
   5:   e8 30 89 e5 e8          call   0xffffffffe8e5893a
   a:   b0 ff                   mov    $0xff,%al
   c:   ff                      (bad)
   d:   ff 5d c3                lcall  *-0x3d(%rbp)
  10:   2e 8d b4 26 00 00 00    cs lea 0x0(%rsi,%riz,1),%esi
  17:   00 
  18:   8d b6 00 00 00 00       lea    0x0(%rsi),%esi
  1e:   3e 8d 74 26 00          ds lea 0x0(%rsi,%riz,1),%esi
  23:   55                      push   %rbp
  24:   89 e5                   mov    %esp,%ebp
  26:   56                      push   %rsi
  27:   53                      push   %rbx
  28:   89 c3                   mov    %eax,%ebx
  2a:*  8b 40 04                mov    0x4(%rax),%eax           <-- trapping 
instruction
  2d:   05 d8 01 00 00          add    $0x1d8,%eax
  32:   e8 67 f5 ff ff          call   0xfffffffffffff59e
  37:   89 d8                   mov    %ebx,%eax
  39:   e8 90 e6 ff ff          call   0xffffffffffffe6ce
  3e:   89 c6                   mov    %eax,%esi

Code starting with the faulting instruction
===========================================
   0:   8b 40 04                mov    0x4(%rax),%eax
   3:   05 d8 01 00 00          add    $0x1d8,%eax
   8:   e8 67 f5 ff ff          call   0xfffffffffffff574
   d:   89 d8                   mov    %ebx,%eax
   f:   e8 90 e6 ff ff          call   0xffffffffffffe6a4
  14:   89 c6                   mov    %eax,%esi
[   12.283887][   T18] EAX: fefefefe EBX: fefefefe ECX: c5923640 EDX: c58b9e28
[   12.283887][   T18] ESI: c58b9f0c EDI: c54024e0 EBP: c58b9ea4 ESP: c58b9e9c
[   12.283887][   T18] DS: 007b ES: 007b FS: 0000 GS: 0000 SS: 0068 EFLAGS: 
00010246
[   12.283887][   T18] CR0: 80050033 CR2: fefeff02 CR3: 04780000 CR4: 000406d0
[   12.283887][   T18] Call Trace:
[ 12.283887][ T18] __start_removing_path (include/linux/fs.h:1024 
fs/namei.c:2784) 
[ 12.283887][ T18] start_removing_path (fs/namei.c:2842) 
[ 12.283887][ T18] devtmpfs_work_loop (drivers/base/devtmpfs.c:326 
drivers/base/devtmpfs.c:387 drivers/base/devtmpfs.c:400) 
[ 12.283887][ T18] devtmpfsd (drivers/base/devtmpfs.c:444) 
[ 12.283887][ T18] kthread (kernel/kthread.c:465) 
[ 12.283887][ T18] ? vclkdev_alloc (drivers/base/devtmpfs.c:436) 
[ 12.283887][ T18] ? kthread_is_per_cpu (kernel/kthread.c:412) 
[ 12.283887][ T18] ret_from_fork (arch/x86/kernel/process.c:154) 
[ 12.283887][ T18] ? kthread_is_per_cpu (kernel/kthread.c:412) 
[ 12.283887][ T18] ret_from_fork_asm (arch/x86/entry/entry_32.S:737) 
[ 12.283887][ T18] entry_INT80_32 (arch/x86/entry/entry_32.S:945) 
[   12.283887][   T18] Modules linked in:
[   12.283887][   T18] CR2: 00000000fefeff02
[   12.283887][   T18] ---[ end trace 0000000000000000 ]---
[ 12.283887][ T18] EIP: mnt_want_write (include/linux/fs.h:1908 
include/linux/fs.h:2044 fs/namespace.c:566) 
[ 12.283887][ T18] Code: 74 26 00 55 83 e8 30 89 e5 e8 b0 ff ff ff 5d c3 2e 8d 
b4 26 00 00 00 00 8d b6 00 00 00 00 3e 8d 74 26 00 55 89 e5 56 53 89 c3 <8b> 40 
04 05 d8 01 00 00 e8 67 f5 ff ff 89 d8 e8 90 e6 ff ff 89 c6
All code
========
   0:   74 26                   je     0x28
   2:   00 55 83                add    %dl,-0x7d(%rbp)
   5:   e8 30 89 e5 e8          call   0xffffffffe8e5893a
   a:   b0 ff                   mov    $0xff,%al
   c:   ff                      (bad)
   d:   ff 5d c3                lcall  *-0x3d(%rbp)
  10:   2e 8d b4 26 00 00 00    cs lea 0x0(%rsi,%riz,1),%esi
  17:   00 
  18:   8d b6 00 00 00 00       lea    0x0(%rsi),%esi
  1e:   3e 8d 74 26 00          ds lea 0x0(%rsi,%riz,1),%esi
  23:   55                      push   %rbp
  24:   89 e5                   mov    %esp,%ebp
  26:   56                      push   %rsi
  27:   53                      push   %rbx
  28:   89 c3                   mov    %eax,%ebx
  2a:*  8b 40 04                mov    0x4(%rax),%eax           <-- trapping 
instruction
  2d:   05 d8 01 00 00          add    $0x1d8,%eax
  32:   e8 67 f5 ff ff          call   0xfffffffffffff59e
  37:   89 d8                   mov    %ebx,%eax
  39:   e8 90 e6 ff ff          call   0xffffffffffffe6ce
  3e:   89 c6                   mov    %eax,%esi

Code starting with the faulting instruction
===========================================
   0:   8b 40 04                mov    0x4(%rax),%eax
   3:   05 d8 01 00 00          add    $0x1d8,%eax
   8:   e8 67 f5 ff ff          call   0xfffffffffffff574
   d:   89 d8                   mov    %ebx,%eax
   f:   e8 90 e6 ff ff          call   0xffffffffffffe6a4
  14:   89 c6                   mov    %eax,%esi


The kernel config and materials to reproduce are available at:
https://download.01.org/0day-ci/archive/20250921/[email protected]



-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki


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