tree:   https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-unstable
head:   9bb8753acdd8c679c474b3531e026dd389a6e46c
commit: 5f408bfe0d1375cebe7a5ebfac1182bbcaf8b887 [34/123] mm: gup: stop abusing try_grab_folio
config: powerpc64-randconfig-003-20240630
compiler: clang version 15.0.7 (https://github.com/llvm/llvm-project 8dfdcc7b7bf66834a761bd8de445840ef68e4d1a)
reproduce (this is a W=1 build):

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/202407010039.D3sIu3fu-lkp@intel.com/

All errors (new ones prefixed by >>):

>> mm/gup.c:474:11: error: call to undeclared function 'try_grab_folio_fast'; ISO C99 and later do not support implicit function declarations [-Werror,-Wimplicit-function-declaration]
                   folio = try_grab_folio_fast(page, refs, flags);
                           ^
   mm/gup.c:474:11: note: did you mean 'try_grab_folio'?
   mm/gup.c:139:18: note: 'try_grab_folio' declared here
   int __must_check try_grab_folio(struct folio *folio, int refs,
                    ^
   mm/gup.c:474:9: error: incompatible integer to pointer conversion assigning to 'struct folio *' from 'int' [-Wint-conversion]
                   folio = try_grab_folio_fast(page, refs, flags);
                         ^ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   mm/gup.c:2747:22: error: static declaration of 'try_grab_folio_fast' follows non-static declaration
   static struct folio *try_grab_folio_fast(struct page *page, int refs,
                        ^
   mm/gup.c:474:11: note: previous implicit declaration is here
                   folio = try_grab_folio_fast(page, refs, flags);
                           ^
   3 errors generated.


vim +/try_grab_folio_fast +474 mm/gup.c

   439	
   440	/*
   441	 * Returns 1 if succeeded, 0 if failed, -EMLINK if unshare needed.
   442	 *
   443	 * NOTE: for the same entry, gup-fast and gup-slow can return different
   444	 * results (0 v.s. -EMLINK) depending on whether vma is available.  This is
   445	 * the expected behavior, where we simply want gup-fast to fallback to
   446	 * gup-slow to take the vma reference first.
   447	 */
   448	static int gup_hugepte(struct vm_area_struct *vma, pte_t *ptep, unsigned long sz,
   449			       unsigned long addr, unsigned long end, unsigned int flags,
   450			       struct page **pages, int *nr, bool fast)
   451	{
   452		unsigned long pte_end;
   453		struct page *page;
   454		struct folio *folio;
   455		pte_t pte;
   456		int refs;
   457	
   458		pte_end = (addr + sz) & ~(sz-1);
   459		if (pte_end < end)
   460			end = pte_end;
   461	
   462		pte = huge_ptep_get(ptep);
   463	
   464		if (!pte_access_permitted(pte, flags & FOLL_WRITE))
   465			return 0;
   466	
   467		/* hugepages are never "special" */
   468		VM_BUG_ON(!pfn_valid(pte_pfn(pte)));
   469	
   470		page = pte_page(pte);
   471		refs = record_subpages(page, sz, addr, end, pages + *nr);
   472	
   473		if (fast) {
 > 474			folio = try_grab_folio_fast(page, refs, flags);
   475			if (!folio)
   476				return 0;
   477		} else {
   478			folio = page_folio(page);
   479			if (try_grab_folio(folio, refs, flags))
   480				return 0;
   481		}
   482	
   483		if (unlikely(pte_val(pte) != pte_val(ptep_get(ptep)))) {
   484			gup_put_folio(folio, refs, flags);
   485			return 0;
   486		}
   487	
   488		if (!pte_write(pte) && gup_must_unshare(vma, flags, &folio->page)) {
   489			gup_put_folio(folio, refs, flags);
   490			return -EMLINK;
   491		}
   492	
   493		*nr += refs;
   494		folio_set_referenced(folio);
   495		return 1;
   496	}
   497	

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