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Message-ID: <202511131448.ZCsuBlBE-lkp@intel.com>
Date: Thu, 13 Nov 2025 15:19:38 +0800
From: kernel test robot <lkp@...el.com>
To: Samuel Holland <samuel.holland@...ive.com>,
Palmer Dabbelt <palmer@...belt.com>, Paul Walmsley <pjw@...nel.org>,
linux-riscv@...ts.infradead.org,
Andrew Morton <akpm@...ux-foundation.org>,
David Hildenbrand <david@...hat.com>
Cc: oe-kbuild-all@...ts.linux.dev,
Linux Memory Management List <linux-mm@...ck.org>,
devicetree@...r.kernel.org, Suren Baghdasaryan <surenb@...gle.com>,
linux-kernel@...r.kernel.org, Mike Rapoport <rppt@...nel.org>,
Michal Hocko <mhocko@...e.com>, Conor Dooley <conor@...nel.org>,
Lorenzo Stoakes <lorenzo.stoakes@...cle.com>,
Krzysztof Kozlowski <krzk@...nel.org>,
Alexandre Ghiti <alex@...ti.fr>,
Emil Renner Berthing <kernel@...il.dk>,
Rob Herring <robh+dt@...nel.org>, Vlastimil Babka <vbabka@...e.cz>,
"Liam R . Howlett" <Liam.Howlett@...cle.com>,
Samuel Holland <samuel.holland@...ive.com>
Subject: Re: [PATCH v3 08/22] mm: Allow page table accessors to be
non-idempotent
Hi Samuel,
kernel test robot noticed the following build errors:
[auto build test ERROR on 24172e0d79900908cf5ebf366600616d29c9b417]
url: https://github.com/intel-lab-lkp/linux/commits/Samuel-Holland/mm-ptdump-replace-READ_ONCE-with-standard-page-table-accessors/20251113-095117
base: 24172e0d79900908cf5ebf366600616d29c9b417
patch link: https://lore.kernel.org/r/20251113014656.2605447-9-samuel.holland%40sifive.com
patch subject: [PATCH v3 08/22] mm: Allow page table accessors to be non-idempotent
config: powerpc-allnoconfig (https://download.01.org/0day-ci/archive/20251113/202511131448.ZCsuBlBE-lkp@intel.com/config)
compiler: powerpc-linux-gcc (GCC) 15.1.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20251113/202511131448.ZCsuBlBE-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@...el.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202511131448.ZCsuBlBE-lkp@intel.com/
All errors (new ones prefixed by >>):
mm/gup.c: In function 'gup_fast_pte_range':
>> mm/gup.c:2848:9: error: implicit declaration of function 'set_pmd'; did you mean 'set_p4d'? [-Wimplicit-function-declaration]
2848 | set_pmd(&pmd, pmd);
| ^~~~~~~
| set_p4d
--
mm/pgtable-generic.c: In function '___pte_offset_map':
>> mm/pgtable-generic.c:303:9: error: implicit declaration of function 'set_pmd'; did you mean 'set_p4d'? [-Wimplicit-function-declaration]
303 | set_pmd(&pmdval, pmdval);
| ^~~~~~~
| set_p4d
vim +2848 mm/gup.c
2819
2820 #ifdef CONFIG_ARCH_HAS_PTE_SPECIAL
2821 /*
2822 * GUP-fast relies on pte change detection to avoid concurrent pgtable
2823 * operations.
2824 *
2825 * To pin the page, GUP-fast needs to do below in order:
2826 * (1) pin the page (by prefetching pte), then (2) check pte not changed.
2827 *
2828 * For the rest of pgtable operations where pgtable updates can be racy
2829 * with GUP-fast, we need to do (1) clear pte, then (2) check whether page
2830 * is pinned.
2831 *
2832 * Above will work for all pte-level operations, including THP split.
2833 *
2834 * For THP collapse, it's a bit more complicated because GUP-fast may be
2835 * walking a pgtable page that is being freed (pte is still valid but pmd
2836 * can be cleared already). To avoid race in such condition, we need to
2837 * also check pmd here to make sure pmd doesn't change (corresponds to
2838 * pmdp_collapse_flush() in the THP collapse code path).
2839 */
2840 static int gup_fast_pte_range(pmd_t pmd, pmd_t *pmdp, unsigned long addr,
2841 unsigned long end, unsigned int flags, struct page **pages,
2842 int *nr)
2843 {
2844 int ret = 0;
2845 pte_t *ptep, *ptem;
2846
2847 /* transform pmd as if &pmd pointed to a hardware page table */
> 2848 set_pmd(&pmd, pmd);
2849 ptem = ptep = pte_offset_map(&pmd, addr);
2850 pmd = pmdp_get(&pmd);
2851 if (!ptep)
2852 return 0;
2853 do {
2854 pte_t pte = ptep_get_lockless(ptep);
2855 struct page *page;
2856 struct folio *folio;
2857
2858 /*
2859 * Always fallback to ordinary GUP on PROT_NONE-mapped pages:
2860 * pte_access_permitted() better should reject these pages
2861 * either way: otherwise, GUP-fast might succeed in
2862 * cases where ordinary GUP would fail due to VMA access
2863 * permissions.
2864 */
2865 if (pte_protnone(pte))
2866 goto pte_unmap;
2867
2868 if (!pte_access_permitted(pte, flags & FOLL_WRITE))
2869 goto pte_unmap;
2870
2871 if (pte_special(pte))
2872 goto pte_unmap;
2873
2874 /* If it's not marked as special it must have a valid memmap. */
2875 VM_WARN_ON_ONCE(!pfn_valid(pte_pfn(pte)));
2876 page = pte_page(pte);
2877
2878 folio = try_grab_folio_fast(page, 1, flags);
2879 if (!folio)
2880 goto pte_unmap;
2881
2882 if (unlikely(pmd_val(pmd) != pmd_val(pmdp_get(pmdp))) ||
2883 unlikely(pte_val(pte) != pte_val(ptep_get(ptep)))) {
2884 gup_put_folio(folio, 1, flags);
2885 goto pte_unmap;
2886 }
2887
2888 if (!gup_fast_folio_allowed(folio, flags)) {
2889 gup_put_folio(folio, 1, flags);
2890 goto pte_unmap;
2891 }
2892
2893 if (!pte_write(pte) && gup_must_unshare(NULL, flags, page)) {
2894 gup_put_folio(folio, 1, flags);
2895 goto pte_unmap;
2896 }
2897
2898 /*
2899 * We need to make the page accessible if and only if we are
2900 * going to access its content (the FOLL_PIN case). Please
2901 * see Documentation/core-api/pin_user_pages.rst for
2902 * details.
2903 */
2904 if ((flags & FOLL_PIN) && arch_make_folio_accessible(folio)) {
2905 gup_put_folio(folio, 1, flags);
2906 goto pte_unmap;
2907 }
2908 folio_set_referenced(folio);
2909 pages[*nr] = page;
2910 (*nr)++;
2911 } while (ptep++, addr += PAGE_SIZE, addr != end);
2912
2913 ret = 1;
2914
2915 pte_unmap:
2916 pte_unmap(ptem);
2917 return ret;
2918 }
2919 #else
2920
--
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki
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