Re: [RFC PATCH 2/4 v1] livedump: Add write protection management

[kernel test robot <lkp@intel.com>]

Hi Lukas,

[This is a private test report for your RFC patch.]
kernel test robot noticed the following build warnings:

[auto build test WARNING on tip/x86/core]
[also build test WARNING on tip/x86/mm linus/master v6.6 next-20231110]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Lukas-Hruska/crash-vmcore-VMCOREINFO-creation-from-non-kdump-kernel/20231111-022332
base:   tip/x86/core
patch link:    https://lore.kernel.org/r/20231110150057.15717-3-lhruska%40suse.cz
patch subject: [RFC PATCH 2/4 v1] livedump: Add write protection management
config: x86_64-allyesconfig (https://download.01.org/0day-ci/archive/20231111/202311111350.ddmhyoBh-lkp@intel.com/config)
compiler: gcc-12 (Debian 12.2.0-14) 12.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20231111/202311111350.ddmhyoBh-lkp@intel.com/reproduce)

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 <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202311111350.ddmhyoBh-lkp@intel.com/

All warnings (new ones prefixed by >>):

   arch/x86/mm/wrprotect.c: In function 'split_large_pages':
>> arch/x86/mm/wrprotect.c:103:13: warning: variable 'ret' set but not used [-Wunused-but-set-variable]
     103 |         int ret;
         |             ^~~
   arch/x86/mm/wrprotect.c: In function 'handle_tasks':
   arch/x86/mm/wrprotect.c:263:9: error: implicit declaration of function 'do_each_thread'; did you mean 'for_each_thread'? [-Werror=implicit-function-declaration]
     263 |         do_each_thread(p, t) {
         |         ^~~~~~~~~~~~~~
         |         for_each_thread
   arch/x86/mm/wrprotect.c:263:29: error: expected ';' before '{' token
     263 |         do_each_thread(p, t) {
         |                             ^~
         |                             ;
   In file included from include/linux/pgtable.h:6,
                    from include/linux/mm.h:29,
                    from arch/x86/include/asm/wrprotect.h:23,
                    from arch/x86/mm/wrprotect.c:21:
   arch/x86/mm/wrprotect.c: In function 'protect_pte':
   arch/x86/include/asm/pgtable.h:461:21: error: too few arguments to function 'pte_mkwrite'
     461 | #define pte_mkwrite pte_mkwrite
         |                     ^~~~~~~~~~~
   arch/x86/mm/wrprotect.c:386:23: note: in expansion of macro 'pte_mkwrite'
     386 |                 pte = pte_mkwrite(pte);
         |                       ^~~~~~~~~~~
   arch/x86/include/asm/pgtable.h:460:7: note: declared here
     460 | pte_t pte_mkwrite(pte_t pte, struct vm_area_struct *vma);
         |       ^~~~~~~~~~~
   arch/x86/mm/wrprotect.c: In function 'wrprotect_uninit':
   arch/x86/mm/wrprotect.c:728:13: warning: variable 'ret' set but not used [-Wunused-but-set-variable]
     728 |         int ret;
         |             ^~~
   cc1: some warnings being treated as errors


vim +/ret +103 arch/x86/mm/wrprotect.c

    95	
    96	/* split_large_pages
    97	 *
    98	 * This function splits all large pages in straight mapping area into 4K ones.
    99	 * Currently wrprotect supports only 4K pages, and so this is needed.
   100	 */
   101	static int split_large_pages(void)
   102	{
 > 103		int ret;
   104		struct mm_walk_ops split_large_pages_walk_ops;
   105	
   106		memset(&split_large_pages_walk_ops, 0, sizeof(struct mm_walk_ops));
   107		split_large_pages_walk_ops.pud_entry = split_large_pages_walk_pud;
   108		split_large_pages_walk_ops.pmd_entry = split_large_pages_walk_pmd;
   109	
   110		mmap_write_lock(&init_mm);
   111		ret = walk_page_range_novma(&init_mm, PAGE_OFFSET, PAGE_OFFSET + DIRECT_MAP_SIZE,
   112			&split_large_pages_walk_ops, init_mm.pgd, NULL);
   113		mmap_write_unlock(&init_mm);
   114	
   115		return 0;
   116	}
   117	

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