CC: [email protected] CC: [email protected] TO: Andrea Arcangeli <[email protected]>
tree: https://git.kernel.org/pub/scm/linux/kernel/git/andrea/aa.git main head: 2f1336124b54750df7ae428da9352e4d8091f31e commit: fec43fa50ccf8365ae2a8d9f150970ab6ca42b18 [44/48] KSM: only attempt to merge with KSM pages if the payload doesn't change :::::: branch date: 2 days ago :::::: commit date: 2 days ago config: i386-randconfig-m021-20211218 (https://download.01.org/0day-ci/archive/20211219/[email protected]/config) compiler: gcc-9 (Debian 9.3.0-22) 9.3.0 If you fix the issue, kindly add following tag as appropriate Reported-by: kernel test robot <[email protected]> Reported-by: Dan Carpenter <[email protected]> smatch warnings: mm/ksm.c:2134 cmp_and_merge_page() error: uninitialized symbol 'checksum'. vim +/checksum +2134 mm/ksm.c 31dbd01f314364 Izik Eidus 2009-09-21 2049 31dbd01f314364 Izik Eidus 2009-09-21 2050 /* 81464e30609cdb Hugh Dickins 2009-09-21 2051 * cmp_and_merge_page - first see if page can be merged into the stable tree; 81464e30609cdb Hugh Dickins 2009-09-21 2052 * if not, compare checksum to previous and if it's the same, see if page can 81464e30609cdb Hugh Dickins 2009-09-21 2053 * be inserted into the unstable tree, or merged with a page already there and 81464e30609cdb Hugh Dickins 2009-09-21 2054 * both transferred to the stable tree. 31dbd01f314364 Izik Eidus 2009-09-21 2055 * 31dbd01f314364 Izik Eidus 2009-09-21 2056 * @page: the page that we are searching identical page to. 31dbd01f314364 Izik Eidus 2009-09-21 2057 * @rmap_item: the reverse mapping into the virtual address of this page 31dbd01f314364 Izik Eidus 2009-09-21 2058 */ 31dbd01f314364 Izik Eidus 2009-09-21 2059 static void cmp_and_merge_page(struct page *page, struct rmap_item *rmap_item) 31dbd01f314364 Izik Eidus 2009-09-21 2060 { 4b22927f0cbd58 Kirill Tkhai 2017-10-03 2061 struct mm_struct *mm = rmap_item->mm; 31dbd01f314364 Izik Eidus 2009-09-21 2062 struct rmap_item *tree_rmap_item; 8dd3557a52f0bc Hugh Dickins 2009-12-14 2063 struct page *tree_page = NULL; 7b6ba2c7d3baf8 Hugh Dickins 2009-12-14 2064 struct stable_node *stable_node; 8dd3557a52f0bc Hugh Dickins 2009-12-14 2065 struct page *kpage; 31dbd01f314364 Izik Eidus 2009-09-21 2066 unsigned int checksum; 31dbd01f314364 Izik Eidus 2009-09-21 2067 int err; 2c653d0ee2ae78 Andrea Arcangeli 2017-07-06 2068 bool max_page_sharing_bypass = false; 31dbd01f314364 Izik Eidus 2009-09-21 2069 4146d2d673e8d6 Hugh Dickins 2013-02-22 2070 stable_node = page_stable_node(page); 4146d2d673e8d6 Hugh Dickins 2013-02-22 2071 if (stable_node) { 4146d2d673e8d6 Hugh Dickins 2013-02-22 2072 if (stable_node->head != &migrate_nodes && 2c653d0ee2ae78 Andrea Arcangeli 2017-07-06 2073 get_kpfn_nid(READ_ONCE(stable_node->kpfn)) != 2c653d0ee2ae78 Andrea Arcangeli 2017-07-06 2074 NUMA(stable_node->nid)) { 2c653d0ee2ae78 Andrea Arcangeli 2017-07-06 2075 stable_node_dup_del(stable_node); 4146d2d673e8d6 Hugh Dickins 2013-02-22 2076 stable_node->head = &migrate_nodes; 4146d2d673e8d6 Hugh Dickins 2013-02-22 2077 list_add(&stable_node->list, stable_node->head); 4146d2d673e8d6 Hugh Dickins 2013-02-22 2078 } 4146d2d673e8d6 Hugh Dickins 2013-02-22 2079 if (stable_node->head != &migrate_nodes && 4146d2d673e8d6 Hugh Dickins 2013-02-22 2080 rmap_item->head == stable_node) 4146d2d673e8d6 Hugh Dickins 2013-02-22 2081 return; 2c653d0ee2ae78 Andrea Arcangeli 2017-07-06 2082 /* 2c653d0ee2ae78 Andrea Arcangeli 2017-07-06 2083 * If it's a KSM fork, allow it to go over the sharing limit 2c653d0ee2ae78 Andrea Arcangeli 2017-07-06 2084 * without warnings. 2c653d0ee2ae78 Andrea Arcangeli 2017-07-06 2085 */ 2c653d0ee2ae78 Andrea Arcangeli 2017-07-06 2086 if (!is_page_sharing_candidate(stable_node)) 2c653d0ee2ae78 Andrea Arcangeli 2017-07-06 2087 max_page_sharing_bypass = true; fec43fa50ccf83 Andrea Arcangeli 2021-11-23 2088 } else { fec43fa50ccf83 Andrea Arcangeli 2021-11-23 2089 /* fec43fa50ccf83 Andrea Arcangeli 2021-11-23 2090 * If the hash value of the page has changed from the last fec43fa50ccf83 Andrea Arcangeli 2021-11-23 2091 * time we calculated it, this page is changing frequently: fec43fa50ccf83 Andrea Arcangeli 2021-11-23 2092 * therefore we don't want to write protect it. fec43fa50ccf83 Andrea Arcangeli 2021-11-23 2093 */ fec43fa50ccf83 Andrea Arcangeli 2021-11-23 2094 checksum = calc_checksum(page); fec43fa50ccf83 Andrea Arcangeli 2021-11-23 2095 if (rmap_item->oldchecksum != checksum) { fec43fa50ccf83 Andrea Arcangeli 2021-11-23 2096 rmap_item->oldchecksum = checksum; fec43fa50ccf83 Andrea Arcangeli 2021-11-23 2097 remove_rmap_item_from_tree(rmap_item); fec43fa50ccf83 Andrea Arcangeli 2021-11-23 2098 return; fec43fa50ccf83 Andrea Arcangeli 2021-11-23 2099 } 4146d2d673e8d6 Hugh Dickins 2013-02-22 2100 } 31dbd01f314364 Izik Eidus 2009-09-21 2101 31dbd01f314364 Izik Eidus 2009-09-21 2102 /* We first start with searching the page inside the stable tree */ 62b61f611eb5e2 Hugh Dickins 2009-12-14 2103 kpage = stable_tree_search(page); 4146d2d673e8d6 Hugh Dickins 2013-02-22 2104 if (kpage == page && rmap_item->head == stable_node) { 4146d2d673e8d6 Hugh Dickins 2013-02-22 2105 put_page(kpage); 4146d2d673e8d6 Hugh Dickins 2013-02-22 2106 return; 4146d2d673e8d6 Hugh Dickins 2013-02-22 2107 } 4146d2d673e8d6 Hugh Dickins 2013-02-22 2108 4146d2d673e8d6 Hugh Dickins 2013-02-22 2109 remove_rmap_item_from_tree(rmap_item); 4146d2d673e8d6 Hugh Dickins 2013-02-22 2110 62b61f611eb5e2 Hugh Dickins 2009-12-14 2111 if (kpage) { 2cee57d1b08877 Yang Shi 2019-03-05 2112 if (PTR_ERR(kpage) == -EBUSY) 2cee57d1b08877 Yang Shi 2019-03-05 2113 return; 2cee57d1b08877 Yang Shi 2019-03-05 2114 08beca44dfb0ab Hugh Dickins 2009-12-14 2115 err = try_to_merge_with_ksm_page(rmap_item, page, kpage); 31dbd01f314364 Izik Eidus 2009-09-21 2116 if (!err) { 31dbd01f314364 Izik Eidus 2009-09-21 2117 /* 31dbd01f314364 Izik Eidus 2009-09-21 2118 * The page was successfully merged: 31dbd01f314364 Izik Eidus 2009-09-21 2119 * add its rmap_item to the stable tree. 31dbd01f314364 Izik Eidus 2009-09-21 2120 */ 5ad6468801d28c Hugh Dickins 2009-12-14 2121 lock_page(kpage); 2c653d0ee2ae78 Andrea Arcangeli 2017-07-06 2122 stable_tree_append(rmap_item, page_stable_node(kpage), 2c653d0ee2ae78 Andrea Arcangeli 2017-07-06 2123 max_page_sharing_bypass); 5ad6468801d28c Hugh Dickins 2009-12-14 2124 unlock_page(kpage); 31dbd01f314364 Izik Eidus 2009-09-21 2125 } 8dd3557a52f0bc Hugh Dickins 2009-12-14 2126 put_page(kpage); 31dbd01f314364 Izik Eidus 2009-09-21 2127 return; 31dbd01f314364 Izik Eidus 2009-09-21 2128 } 31dbd01f314364 Izik Eidus 2009-09-21 2129 e86c59b1b12d0d Claudio Imbrenda 2017-02-24 2130 /* e86c59b1b12d0d Claudio Imbrenda 2017-02-24 2131 * Same checksum as an empty page. We attempt to merge it with the e86c59b1b12d0d Claudio Imbrenda 2017-02-24 2132 * appropriate zero page if the user enabled this via sysfs. e86c59b1b12d0d Claudio Imbrenda 2017-02-24 2133 */ e86c59b1b12d0d Claudio Imbrenda 2017-02-24 @2134 if (ksm_use_zero_pages && (checksum == zero_checksum)) { e86c59b1b12d0d Claudio Imbrenda 2017-02-24 2135 struct vm_area_struct *vma; e86c59b1b12d0d Claudio Imbrenda 2017-02-24 2136 d8ed45c5dcd455 Michel Lespinasse 2020-06-08 2137 mmap_read_lock(mm); 4b22927f0cbd58 Kirill Tkhai 2017-10-03 2138 vma = find_mergeable_vma(mm, rmap_item->address); 56df70a63ed5d9 Muchun Song 2020-04-20 2139 if (vma) { e86c59b1b12d0d Claudio Imbrenda 2017-02-24 2140 err = try_to_merge_one_page(vma, page, e86c59b1b12d0d Claudio Imbrenda 2017-02-24 2141 ZERO_PAGE(rmap_item->address)); 56df70a63ed5d9 Muchun Song 2020-04-20 2142 } else { 56df70a63ed5d9 Muchun Song 2020-04-20 2143 /* 56df70a63ed5d9 Muchun Song 2020-04-20 2144 * If the vma is out of date, we do not need to 56df70a63ed5d9 Muchun Song 2020-04-20 2145 * continue. 56df70a63ed5d9 Muchun Song 2020-04-20 2146 */ 56df70a63ed5d9 Muchun Song 2020-04-20 2147 err = 0; 56df70a63ed5d9 Muchun Song 2020-04-20 2148 } d8ed45c5dcd455 Michel Lespinasse 2020-06-08 2149 mmap_read_unlock(mm); e86c59b1b12d0d Claudio Imbrenda 2017-02-24 2150 /* e86c59b1b12d0d Claudio Imbrenda 2017-02-24 2151 * In case of failure, the page was not really empty, so we e86c59b1b12d0d Claudio Imbrenda 2017-02-24 2152 * need to continue. Otherwise we're done. e86c59b1b12d0d Claudio Imbrenda 2017-02-24 2153 */ e86c59b1b12d0d Claudio Imbrenda 2017-02-24 2154 if (!err) e86c59b1b12d0d Claudio Imbrenda 2017-02-24 2155 return; e86c59b1b12d0d Claudio Imbrenda 2017-02-24 2156 } 8dd3557a52f0bc Hugh Dickins 2009-12-14 2157 tree_rmap_item = 8dd3557a52f0bc Hugh Dickins 2009-12-14 2158 unstable_tree_search_insert(rmap_item, page, &tree_page); 31dbd01f314364 Izik Eidus 2009-09-21 2159 if (tree_rmap_item) { 77da2ba0648a4f Claudio Imbrenda 2018-04-05 2160 bool split; 77da2ba0648a4f Claudio Imbrenda 2018-04-05 2161 8dd3557a52f0bc Hugh Dickins 2009-12-14 2162 kpage = try_to_merge_two_pages(rmap_item, page, 8dd3557a52f0bc Hugh Dickins 2009-12-14 2163 tree_rmap_item, tree_page); 77da2ba0648a4f Claudio Imbrenda 2018-04-05 2164 /* 77da2ba0648a4f Claudio Imbrenda 2018-04-05 2165 * If both pages we tried to merge belong to the same compound 77da2ba0648a4f Claudio Imbrenda 2018-04-05 2166 * page, then we actually ended up increasing the reference 77da2ba0648a4f Claudio Imbrenda 2018-04-05 2167 * count of the same compound page twice, and split_huge_page 77da2ba0648a4f Claudio Imbrenda 2018-04-05 2168 * failed. 77da2ba0648a4f Claudio Imbrenda 2018-04-05 2169 * Here we set a flag if that happened, and we use it later to 77da2ba0648a4f Claudio Imbrenda 2018-04-05 2170 * try split_huge_page again. Since we call put_page right 77da2ba0648a4f Claudio Imbrenda 2018-04-05 2171 * afterwards, the reference count will be correct and 77da2ba0648a4f Claudio Imbrenda 2018-04-05 2172 * split_huge_page should succeed. 77da2ba0648a4f Claudio Imbrenda 2018-04-05 2173 */ 77da2ba0648a4f Claudio Imbrenda 2018-04-05 2174 split = PageTransCompound(page) 77da2ba0648a4f Claudio Imbrenda 2018-04-05 2175 && compound_head(page) == compound_head(tree_page); 8dd3557a52f0bc Hugh Dickins 2009-12-14 2176 put_page(tree_page); bc56620b493496 Hugh Dickins 2013-02-22 2177 if (kpage) { 31dbd01f314364 Izik Eidus 2009-09-21 2178 /* bc56620b493496 Hugh Dickins 2013-02-22 2179 * The pages were successfully merged: insert new bc56620b493496 Hugh Dickins 2013-02-22 2180 * node in the stable tree and add both rmap_items. 31dbd01f314364 Izik Eidus 2009-09-21 2181 */ 5ad6468801d28c Hugh Dickins 2009-12-14 2182 lock_page(kpage); 7b6ba2c7d3baf8 Hugh Dickins 2009-12-14 2183 stable_node = stable_tree_insert(kpage); 7b6ba2c7d3baf8 Hugh Dickins 2009-12-14 2184 if (stable_node) { 2c653d0ee2ae78 Andrea Arcangeli 2017-07-06 2185 stable_tree_append(tree_rmap_item, stable_node, 2c653d0ee2ae78 Andrea Arcangeli 2017-07-06 2186 false); 2c653d0ee2ae78 Andrea Arcangeli 2017-07-06 2187 stable_tree_append(rmap_item, stable_node, 2c653d0ee2ae78 Andrea Arcangeli 2017-07-06 2188 false); 7b6ba2c7d3baf8 Hugh Dickins 2009-12-14 2189 } 5ad6468801d28c Hugh Dickins 2009-12-14 2190 unlock_page(kpage); 7b6ba2c7d3baf8 Hugh Dickins 2009-12-14 2191 31dbd01f314364 Izik Eidus 2009-09-21 2192 /* 31dbd01f314364 Izik Eidus 2009-09-21 2193 * If we fail to insert the page into the stable tree, 31dbd01f314364 Izik Eidus 2009-09-21 2194 * we will have 2 virtual addresses that are pointing 31dbd01f314364 Izik Eidus 2009-09-21 2195 * to a ksm page left outside the stable tree, 31dbd01f314364 Izik Eidus 2009-09-21 2196 * in which case we need to break_cow on both. 31dbd01f314364 Izik Eidus 2009-09-21 2197 */ 7b6ba2c7d3baf8 Hugh Dickins 2009-12-14 2198 if (!stable_node) { 8dd3557a52f0bc Hugh Dickins 2009-12-14 2199 break_cow(tree_rmap_item); 8dd3557a52f0bc Hugh Dickins 2009-12-14 2200 break_cow(rmap_item); 31dbd01f314364 Izik Eidus 2009-09-21 2201 } 77da2ba0648a4f Claudio Imbrenda 2018-04-05 2202 } else if (split) { 77da2ba0648a4f Claudio Imbrenda 2018-04-05 2203 /* 77da2ba0648a4f Claudio Imbrenda 2018-04-05 2204 * We are here if we tried to merge two pages and 77da2ba0648a4f Claudio Imbrenda 2018-04-05 2205 * failed because they both belonged to the same 77da2ba0648a4f Claudio Imbrenda 2018-04-05 2206 * compound page. We will split the page now, but no 77da2ba0648a4f Claudio Imbrenda 2018-04-05 2207 * merging will take place. 77da2ba0648a4f Claudio Imbrenda 2018-04-05 2208 * We do not want to add the cost of a full lock; if 77da2ba0648a4f Claudio Imbrenda 2018-04-05 2209 * the page is locked, it is better to skip it and 77da2ba0648a4f Claudio Imbrenda 2018-04-05 2210 * perhaps try again later. 77da2ba0648a4f Claudio Imbrenda 2018-04-05 2211 */ 77da2ba0648a4f Claudio Imbrenda 2018-04-05 2212 if (!trylock_page(page)) 77da2ba0648a4f Claudio Imbrenda 2018-04-05 2213 return; 77da2ba0648a4f Claudio Imbrenda 2018-04-05 2214 split_huge_page(page); 77da2ba0648a4f Claudio Imbrenda 2018-04-05 2215 unlock_page(page); 31dbd01f314364 Izik Eidus 2009-09-21 2216 } 31dbd01f314364 Izik Eidus 2009-09-21 2217 } 31dbd01f314364 Izik Eidus 2009-09-21 2218 } 31dbd01f314364 Izik Eidus 2009-09-21 2219 :::::: The code at line 2134 was first introduced by commit :::::: e86c59b1b12d0db1c97eb5bec7586a691685c6cc mm/ksm: improve deduplication of zero pages with colouring :::::: TO: Claudio Imbrenda <[email protected]> :::::: CC: Linus Torvalds <[email protected]> --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/[email protected] _______________________________________________ kbuild mailing list -- [email protected] To unsubscribe send an email to [email protected]
