Re: [PATCH 2/2] mm/MADV_COLLAPSE: catch !none !huge !bad pmd lookups

[kernel test robot]

Hi Zach,

Thank you for the patch! Yet something to improve:

[auto build test ERROR on akpm-mm/mm-everything]

url:    https://github.com/intel-lab-lkp/linux/commits/Zach-O-Keefe/mm-MADV_COLLAPSE-catch-none-huge-bad-pmd-lookups/20230125-095954
base:   https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-everything
patch link:    https://lore.kernel.org/r/20230125015738.912924-2-zokeefe%40google.com
patch subject: [PATCH 2/2] mm/MADV_COLLAPSE: catch !none !huge !bad pmd lookups
config: x86_64-rhel-8.3-kselftests (https://download.01.org/0day-ci/archive/20230125/202301252110.hFYRsbrm-lkp@xxxxxxxxx/config)
compiler: gcc-11 (Debian 11.3.0-8) 11.3.0
reproduce (this is a W=1 build):
        # https://github.com/intel-lab-lkp/linux/commit/6001eb9a8f1687a1d0b72831d991886106cac37b
        git remote add linux-review https://github.com/intel-lab-lkp/linux
        git fetch --no-tags linux-review Zach-O-Keefe/mm-MADV_COLLAPSE-catch-none-huge-bad-pmd-lookups/20230125-095954
        git checkout 6001eb9a8f1687a1d0b72831d991886106cac37b
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        make W=1 O=build_dir ARCH=x86_64 olddefconfig
        make W=1 O=build_dir ARCH=x86_64 SHELL=/bin/bash

If you fix the issue, kindly add following tag where applicable
| Reported-by: kernel test robot <lkp@xxxxxxxxx>

All errors (new ones prefixed by >>):

   mm/khugepaged.c: In function 'find_pmd_or_thp_or_none':
>> mm/khugepaged.c:972:24: error: incompatible type for argument 1 of 'pmd_devmap'
     972 |         if (pmd_devmap(pmd))
         |                        ^~~
         |                        |
         |                        pmd_t **
   In file included from include/linux/pgtable.h:6,
                    from include/linux/mm.h:29,
                    from mm/khugepaged.c:4:
   arch/x86/include/asm/pgtable.h:254:36: note: expected 'pmd_t' but argument is of type 'pmd_t **'
     254 | static inline int pmd_devmap(pmd_t pmd)
         |                              ~~~~~~^~~


vim +/pmd_devmap +972 mm/khugepaged.c

   945	
   946	/*
   947	 * See pmd_trans_unstable() for how the result may change out from
   948	 * underneath us, even if we hold mmap_lock in read.
   949	 */
   950	static int find_pmd_or_thp_or_none(struct mm_struct *mm,
   951					   unsigned long address,
   952					   pmd_t **pmd)
   953	{
   954		pmd_t pmde;
   955	
   956		*pmd = mm_find_pmd(mm, address);
   957		if (!*pmd)
   958			return SCAN_PMD_NULL;
   959	
   960		pmde = pmdp_get_lockless(*pmd);
   961	
   962	#ifdef CONFIG_TRANSPARENT_HUGEPAGE
   963		/* See comments in pmd_none_or_trans_huge_or_clear_bad() */
   964		barrier();
   965	#endif
   966		if (pmd_none(pmde))
   967			return SCAN_PMD_NONE;
   968		if (!pmd_present(pmde))
   969			return SCAN_PMD_NULL;
   970		if (pmd_trans_huge(pmde))
   971			return SCAN_PMD_MAPPED;
 > 972		if (pmd_devmap(pmd))
   973			return SCAN_PMD_NULL;
   974		if (pmd_bad(pmde))
   975			return SCAN_PMD_NULL;
   976		return SCAN_SUCCEED;
   977	}
   978	

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