Re: [PATCH] mm/swap: Fix lost swap bits in unuse_pte()

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

Hi Peter,

Thank you for the patch! Yet something to improve:

[auto build test ERROR on hnaz-mm/master]

url:    https://github.com/intel-lab-lkp/linux/commits/Peter-Xu/mm-swap-Fix-lost-swap-bits-in-unuse_pte/20220420-053845
base:   https://github.com/hnaz/linux-mm master
config: s390-randconfig-r023-20220420 (https://download.01.org/0day-ci/archive/20220420/202204201313.QYiDBRbL-lkp@intel.com/config)
compiler: clang version 15.0.0 (https://github.com/llvm/llvm-project bac6cd5bf85669e3376610cfc4c4f9ca015e7b9b)
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # install s390 cross compiling tool for clang build
        # apt-get install binutils-s390x-linux-gnu
        # https://github.com/intel-lab-lkp/linux/commit/355ac3eb45402f7aab25b76af029d4390af05238
        git remote add linux-review https://github.com/intel-lab-lkp/linux
        git fetch --no-tags linux-review Peter-Xu/mm-swap-Fix-lost-swap-bits-in-unuse_pte/20220420-053845
        git checkout 355ac3eb45402f7aab25b76af029d4390af05238
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=s390 SHELL=/bin/bash

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>

All errors (new ones prefixed by >>):

>> mm/swapfile.c:1824:2: error: use of undeclared identifier 'new_pte'; did you mean 'newpte'?
           new_pte = pte_mkold(mk_pte(page, vma->vm_page_prot));
           ^~~~~~~
           newpte
   mm/swapfile.c:1786:14: note: 'newpte' declared here
           pte_t *pte, newpte;
                       ^
   mm/swapfile.c:1826:26: error: use of undeclared identifier 'new_pte'
                   pte = pte_mksoft_dirty(new_pte);
                                          ^
   mm/swapfile.c:1828:23: error: use of undeclared identifier 'new_pte'
                   pte = pte_mkuffd_wp(new_pte);
                                       ^
   mm/swapfile.c:1829:36: error: use of undeclared identifier 'new_pte'; did you mean 'newpte'?
           set_pte_at(vma->vm_mm, addr, pte, new_pte);
                                             ^~~~~~~
                                             newpte
   mm/swapfile.c:1786:14: note: 'newpte' declared here
           pte_t *pte, newpte;
                       ^
   4 errors generated.


vim +1824 mm/swapfile.c

  1775	
  1776	/*
  1777	 * No need to decide whether this PTE shares the swap entry with others,
  1778	 * just let do_wp_page work it out if a write is requested later - to
  1779	 * force COW, vm_page_prot omits write permission from any private vma.
  1780	 */
  1781	static int unuse_pte(struct vm_area_struct *vma, pmd_t *pmd,
  1782			unsigned long addr, swp_entry_t entry, struct page *page)
  1783	{
  1784		struct page *swapcache;
  1785		spinlock_t *ptl;
  1786		pte_t *pte, newpte;
  1787		int ret = 1;
  1788	
  1789		swapcache = page;
  1790		page = ksm_might_need_to_copy(page, vma, addr);
  1791		if (unlikely(!page))
  1792			return -ENOMEM;
  1793	
  1794		pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
  1795		if (unlikely(!pte_same_as_swp(*pte, swp_entry_to_pte(entry)))) {
  1796			ret = 0;
  1797			goto out;
  1798		}
  1799	
  1800		/* See do_swap_page() */
  1801		BUG_ON(!PageAnon(page) && PageMappedToDisk(page));
  1802		BUG_ON(PageAnon(page) && PageAnonExclusive(page));
  1803	
  1804		dec_mm_counter(vma->vm_mm, MM_SWAPENTS);
  1805		inc_mm_counter(vma->vm_mm, MM_ANONPAGES);
  1806		get_page(page);
  1807		if (page == swapcache) {
  1808			rmap_t rmap_flags = RMAP_NONE;
  1809	
  1810			/*
  1811			 * See do_swap_page(): PageWriteback() would be problematic.
  1812			 * However, we do a wait_on_page_writeback() just before this
  1813			 * call and have the page locked.
  1814			 */
  1815			VM_BUG_ON_PAGE(PageWriteback(page), page);
  1816			if (pte_swp_exclusive(*pte))
  1817				rmap_flags |= RMAP_EXCLUSIVE;
  1818	
  1819			page_add_anon_rmap(page, vma, addr, rmap_flags);
  1820		} else { /* ksm created a completely new copy */
  1821			page_add_new_anon_rmap(page, vma, addr);
  1822			lru_cache_add_inactive_or_unevictable(page, vma);
  1823		}
> 1824		new_pte = pte_mkold(mk_pte(page, vma->vm_page_prot));
  1825		if (pte_swp_soft_dirty(*pte))
  1826			pte = pte_mksoft_dirty(new_pte);
  1827		if (pte_swp_uffd_wp(*pte))
  1828			pte = pte_mkuffd_wp(new_pte);
  1829		set_pte_at(vma->vm_mm, addr, pte, new_pte);
  1830		swap_free(entry);
  1831	out:
  1832		pte_unmap_unlock(pte, ptl);
  1833		if (page != swapcache) {
  1834			unlock_page(page);
  1835			put_page(page);
  1836		}
  1837		return ret;
  1838	}
  1839	

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