linux-kernel - Re: [PATCH 3/3] mm: don't remap clean subpages when splitting isolated thp

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Date:   Sat, 31 Jul 2021 17:53:51 +0800
From:   kernel test robot <lkp@...el.com>
To:     Yu Zhao <yuzhao@...gle.com>, linux-mm@...ck.org
Cc:     clang-built-linux@...glegroups.com, kbuild-all@...ts.01.org,
        Andrew Morton <akpm@...ux-foundation.org>,
        Linux Memory Management List <linux-mm@...ck.org>,
        Hugh Dickins <hughd@...gle.com>,
        "Kirill A . Shutemov" <kirill.shutemov@...ux.intel.com>,
        Matthew Wilcox <willy@...radead.org>,
        Vlastimil Babka <vbabka@...e.cz>,
        Yang Shi <shy828301@...il.com>, Zi Yan <ziy@...dia.com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/3] mm: don't remap clean subpages when splitting
 isolated thp

Hi Yu,

Thank you for the patch! Yet something to improve:

[auto build test ERROR on linus/master]
[also build test ERROR on v5.14-rc3]
[cannot apply to hnaz-linux-mm/master linux/master next-20210730]
[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]

url:    https://github.com/0day-ci/linux/commits/Yu-Zhao/mm-optimize-thp-for-reclaim-and-migration/20210731-144129
base:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git c7d102232649226a69dddd58a4942cf13cff4f7c
config: x86_64-randconfig-a001-20210730 (attached as .config)
compiler: clang version 13.0.0 (https://github.com/llvm/llvm-project 4f71f59bf3d9914188a11d0c41bedbb339d36ff5)
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
        # https://github.com/0day-ci/linux/commit/e4e76c4915b364558aacae2cf320a43306a20fa1
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review Yu-Zhao/mm-optimize-thp-for-reclaim-and-migration/20210731-144129
        git checkout e4e76c4915b364558aacae2cf320a43306a20fa1
        # save the attached .config to linux build tree
        mkdir build_dir
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross O=build_dir ARCH=x86_64 SHELL=/bin/bash

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

All errors (new ones prefixed by >>):

>> mm/migrate.c:199:17: error: use of undeclared identifier 'THP_SPLIT_UNMAP'
           count_vm_event(THP_SPLIT_UNMAP);
                          ^
   mm/migrate.c:2606:16: warning: variable 'addr' set but not used [-Wunused-but-set-variable]
           unsigned long addr, i, restore = 0;
                         ^
   1 warning and 1 error generated.


vim +/THP_SPLIT_UNMAP +199 mm/migrate.c

   170	
   171	static bool try_to_unmap_clean(struct page_vma_mapped_walk *pvmw, struct page *page)
   172	{
   173		void *addr;
   174		bool dirty;
   175	
   176		VM_BUG_ON_PAGE(PageLRU(page), page);
   177		VM_BUG_ON_PAGE(PageCompound(page), page);
   178		VM_BUG_ON_PAGE(!PageAnon(page), page);
   179		VM_BUG_ON_PAGE(!PageLocked(page), page);
   180		VM_BUG_ON_PAGE(pte_present(*pvmw->pte), page);
   181	
   182		if (PageMlocked(page) || (pvmw->vma->vm_flags & VM_LOCKED))
   183			return false;
   184	
   185		/*
   186		 * The pmd entry mapping the old thp was flushed and the pte mapping
   187		 * this subpage has been non present. Therefore, this subpage is
   188		 * inaccessible. We don't need to remap it if it contains only zeros.
   189		 */
   190		addr = kmap_atomic(page);
   191		dirty = !!memchr_inv(addr, 0, PAGE_SIZE);
   192		kunmap_atomic(addr);
   193	
   194		if (dirty)
   195			return false;
   196	
   197		pte_clear_not_present_full(pvmw->vma->vm_mm, pvmw->address, pvmw->pte, false);
   198		dec_mm_counter(pvmw->vma->vm_mm, mm_counter(page));
 > 199		count_vm_event(THP_SPLIT_UNMAP);
   200	
   201		return true;
   202	}
   203	

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org

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