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Date:   Tue, 13 Dec 2022 19:33:22 +0800
From:   kernel test robot <lkp@...el.com>
To:     Kefeng Wang <wangkefeng.wang@...wei.com>, naoya.horiguchi@....com,
        akpm@...ux-foundation.org, linux-mm@...ck.org
Cc:     llvm@...ts.linux.dev, oe-kbuild-all@...ts.linux.dev,
        tony.luck@...el.com, linux-kernel@...r.kernel.org,
        linmiaohe@...wei.com, David Hildenbrand <david@...hat.com>,
        Kefeng Wang <wangkefeng.wang@...wei.com>
Subject: Re: [PATCH -next v3] mm: hwposion: support recovery from
 ksm_might_need_to_copy()

Hi Kefeng,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on next-20221208]
[cannot apply to akpm-mm/mm-everything linus/master v6.1 v6.1-rc8 v6.1-rc7 v6.1]
[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#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Kefeng-Wang/mm-hwposion-support-recovery-from-ksm_might_need_to_copy/20221213-105100
patch link:    https://lore.kernel.org/r/20221213030557.143432-1-wangkefeng.wang%40huawei.com
patch subject: [PATCH -next v3] mm: hwposion: support recovery from ksm_might_need_to_copy()
config: i386-randconfig-a002
compiler: clang version 14.0.6 (https://github.com/llvm/llvm-project f28c006a5895fc0e329fe15fead81e37457cb1d1)
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/intel-lab-lkp/linux/commit/0015a0b43762219cbe6edac8bb9e7e385978152b
        git remote add linux-review https://github.com/intel-lab-lkp/linux
        git fetch --no-tags linux-review Kefeng-Wang/mm-hwposion-support-recovery-from-ksm_might_need_to_copy/20221213-105100
        git checkout 0015a0b43762219cbe6edac8bb9e7e385978152b
        # 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=i386 SHELL=/bin/bash

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

All warnings (new ones prefixed by >>):

>> mm/swapfile.c:1777:6: warning: variable 'new_pte' is used uninitialized whenever 'if' condition is true [-Wsometimes-uninitialized]
           if (unlikely(!pte_same_as_swp(*pte, swp_entry_to_pte(entry)))) {
               ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   include/linux/compiler.h:78:22: note: expanded from macro 'unlikely'
   # define unlikely(x)    __builtin_expect(!!(x), 0)
                           ^~~~~~~~~~~~~~~~~~~~~~~~~~
   mm/swapfile.c:1827:36: note: uninitialized use occurs here
           set_pte_at(vma->vm_mm, addr, pte, new_pte);
                                             ^~~~~~~
   mm/swapfile.c:1777:2: note: remove the 'if' if its condition is always false
           if (unlikely(!pte_same_as_swp(*pte, swp_entry_to_pte(entry)))) {
           ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   mm/swapfile.c:1765:2: note: variable 'new_pte' is declared here
           pte_t *pte, new_pte;
           ^
   1 warning generated.


vim +1777 mm/swapfile.c

179ef71cbc0852 Cyrill Gorcunov         2013-08-13  1753  
^1da177e4c3f41 Linus Torvalds          2005-04-16  1754  /*
72866f6f277ec0 Hugh Dickins            2005-10-29  1755   * No need to decide whether this PTE shares the swap entry with others,
72866f6f277ec0 Hugh Dickins            2005-10-29  1756   * just let do_wp_page work it out if a write is requested later - to
72866f6f277ec0 Hugh Dickins            2005-10-29  1757   * force COW, vm_page_prot omits write permission from any private vma.
^1da177e4c3f41 Linus Torvalds          2005-04-16  1758   */
044d66c1d2b1c5 Hugh Dickins            2008-02-07  1759  static int unuse_pte(struct vm_area_struct *vma, pmd_t *pmd,
f102cd8b173e06 Matthew Wilcox (Oracle  2022-09-02  1760) 		unsigned long addr, swp_entry_t entry, struct folio *folio)
^1da177e4c3f41 Linus Torvalds          2005-04-16  1761  {
f102cd8b173e06 Matthew Wilcox (Oracle  2022-09-02  1762) 	struct page *page = folio_file_page(folio, swp_offset(entry));
9e16b7fb1d066d Hugh Dickins            2013-02-22  1763  	struct page *swapcache;
044d66c1d2b1c5 Hugh Dickins            2008-02-07  1764  	spinlock_t *ptl;
14a762dd1977cf Miaohe Lin              2022-05-19  1765  	pte_t *pte, new_pte;
0015a0b4376221 Kefeng Wang             2022-12-13  1766  	bool hwposioned = false;
044d66c1d2b1c5 Hugh Dickins            2008-02-07  1767  	int ret = 1;
044d66c1d2b1c5 Hugh Dickins            2008-02-07  1768  
9e16b7fb1d066d Hugh Dickins            2013-02-22  1769  	swapcache = page;
9e16b7fb1d066d Hugh Dickins            2013-02-22  1770  	page = ksm_might_need_to_copy(page, vma, addr);
9e16b7fb1d066d Hugh Dickins            2013-02-22  1771  	if (unlikely(!page))
9e16b7fb1d066d Hugh Dickins            2013-02-22  1772  		return -ENOMEM;
0015a0b4376221 Kefeng Wang             2022-12-13  1773  	else if (unlikely(PTR_ERR(page) == -EHWPOISON))
0015a0b4376221 Kefeng Wang             2022-12-13  1774  		hwposioned = true;
9e16b7fb1d066d Hugh Dickins            2013-02-22  1775  
044d66c1d2b1c5 Hugh Dickins            2008-02-07  1776  	pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
9f8bdb3f3dad3f Hugh Dickins            2016-01-15 @1777  	if (unlikely(!pte_same_as_swp(*pte, swp_entry_to_pte(entry)))) {
044d66c1d2b1c5 Hugh Dickins            2008-02-07  1778  		ret = 0;
044d66c1d2b1c5 Hugh Dickins            2008-02-07  1779  		goto out;
044d66c1d2b1c5 Hugh Dickins            2008-02-07  1780  	}
8a9f3ccd24741b Balbir Singh            2008-02-07  1781  
0015a0b4376221 Kefeng Wang             2022-12-13  1782  	if (hwposioned || !PageUptodate(page)) {
0015a0b4376221 Kefeng Wang             2022-12-13  1783  		swp_entry_t swp_entry;
9f186f9e5fa9eb Miaohe Lin              2022-05-19  1784  
9f186f9e5fa9eb Miaohe Lin              2022-05-19  1785  		dec_mm_counter(vma->vm_mm, MM_SWAPENTS);
0015a0b4376221 Kefeng Wang             2022-12-13  1786  		if (hwposioned) {
0015a0b4376221 Kefeng Wang             2022-12-13  1787  			swp_entry = make_hwpoison_entry(swapcache);
0015a0b4376221 Kefeng Wang             2022-12-13  1788  			page = swapcache;
0015a0b4376221 Kefeng Wang             2022-12-13  1789  		} else {
0015a0b4376221 Kefeng Wang             2022-12-13  1790  			swp_entry = make_swapin_error_entry();
0015a0b4376221 Kefeng Wang             2022-12-13  1791  		}
0015a0b4376221 Kefeng Wang             2022-12-13  1792  		new_pte = swp_entry_to_pte(swp_entry);
9f186f9e5fa9eb Miaohe Lin              2022-05-19  1793  		ret = 0;
9f186f9e5fa9eb Miaohe Lin              2022-05-19  1794  		goto out;
9f186f9e5fa9eb Miaohe Lin              2022-05-19  1795  	}
9f186f9e5fa9eb Miaohe Lin              2022-05-19  1796  
78fbe906cc900b David Hildenbrand       2022-05-09  1797  	/* See do_swap_page() */
78fbe906cc900b David Hildenbrand       2022-05-09  1798  	BUG_ON(!PageAnon(page) && PageMappedToDisk(page));
78fbe906cc900b David Hildenbrand       2022-05-09  1799  	BUG_ON(PageAnon(page) && PageAnonExclusive(page));
78fbe906cc900b David Hildenbrand       2022-05-09  1800  
b084d4353ff99d KAMEZAWA Hiroyuki       2010-03-05  1801  	dec_mm_counter(vma->vm_mm, MM_SWAPENTS);
d559db086ff5be KAMEZAWA Hiroyuki       2010-03-05  1802  	inc_mm_counter(vma->vm_mm, MM_ANONPAGES);
^1da177e4c3f41 Linus Torvalds          2005-04-16  1803  	get_page(page);
00501b531c4723 Johannes Weiner         2014-08-08  1804  	if (page == swapcache) {
1493a1913e34b0 David Hildenbrand       2022-05-09  1805  		rmap_t rmap_flags = RMAP_NONE;
1493a1913e34b0 David Hildenbrand       2022-05-09  1806  
1493a1913e34b0 David Hildenbrand       2022-05-09  1807  		/*
1493a1913e34b0 David Hildenbrand       2022-05-09  1808  		 * See do_swap_page(): PageWriteback() would be problematic.
1493a1913e34b0 David Hildenbrand       2022-05-09  1809  		 * However, we do a wait_on_page_writeback() just before this
1493a1913e34b0 David Hildenbrand       2022-05-09  1810  		 * call and have the page locked.
1493a1913e34b0 David Hildenbrand       2022-05-09  1811  		 */
1493a1913e34b0 David Hildenbrand       2022-05-09  1812  		VM_BUG_ON_PAGE(PageWriteback(page), page);
1493a1913e34b0 David Hildenbrand       2022-05-09  1813  		if (pte_swp_exclusive(*pte))
1493a1913e34b0 David Hildenbrand       2022-05-09  1814  			rmap_flags |= RMAP_EXCLUSIVE;
1493a1913e34b0 David Hildenbrand       2022-05-09  1815  
1493a1913e34b0 David Hildenbrand       2022-05-09  1816  		page_add_anon_rmap(page, vma, addr, rmap_flags);
00501b531c4723 Johannes Weiner         2014-08-08  1817  	} else { /* ksm created a completely new copy */
40f2bbf71161fa David Hildenbrand       2022-05-09  1818  		page_add_new_anon_rmap(page, vma, addr);
b518154e59aab3 Joonsoo Kim             2020-08-11  1819  		lru_cache_add_inactive_or_unevictable(page, vma);
00501b531c4723 Johannes Weiner         2014-08-08  1820  	}
14a762dd1977cf Miaohe Lin              2022-05-19  1821  	new_pte = pte_mkold(mk_pte(page, vma->vm_page_prot));
14a762dd1977cf Miaohe Lin              2022-05-19  1822  	if (pte_swp_soft_dirty(*pte))
14a762dd1977cf Miaohe Lin              2022-05-19  1823  		new_pte = pte_mksoft_dirty(new_pte);
14a762dd1977cf Miaohe Lin              2022-05-19  1824  	if (pte_swp_uffd_wp(*pte))
14a762dd1977cf Miaohe Lin              2022-05-19  1825  		new_pte = pte_mkuffd_wp(new_pte);
0015a0b4376221 Kefeng Wang             2022-12-13  1826  out:
14a762dd1977cf Miaohe Lin              2022-05-19  1827  	set_pte_at(vma->vm_mm, addr, pte, new_pte);
^1da177e4c3f41 Linus Torvalds          2005-04-16  1828  	swap_free(entry);
044d66c1d2b1c5 Hugh Dickins            2008-02-07  1829  	pte_unmap_unlock(pte, ptl);
9e16b7fb1d066d Hugh Dickins            2013-02-22  1830  	if (page != swapcache) {
9e16b7fb1d066d Hugh Dickins            2013-02-22  1831  		unlock_page(page);
9e16b7fb1d066d Hugh Dickins            2013-02-22  1832  		put_page(page);
9e16b7fb1d066d Hugh Dickins            2013-02-22  1833  	}
044d66c1d2b1c5 Hugh Dickins            2008-02-07  1834  	return ret;
^1da177e4c3f41 Linus Torvalds          2005-04-16  1835  }
^1da177e4c3f41 Linus Torvalds          2005-04-16  1836  

-- 
0-DAY CI Kernel Test Service
https://01.org/lkp

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