Hi Andrea, Thank you for the patch! Yet something to improve: [auto build test ERROR on linux-sof-driver/master] [also build test ERROR on v4.19-rc7 next-20181012] [if your patch is applied to the wrong git tree, please drop us a note to help improve the system] url: https://github.com/0day-ci/linux/commits/Andrea-Arcangeli/mm-thp-fix-MADV_DONTNEED-vs-migrate_misplaced_transhuge_page-race-condition/20181014-143004 base: https://github.com/thesofproject/linux master config: arm64-defconfig (attached as .config) compiler: aarch64-linux-gnu-gcc (Debian 7.2.0-11) 7.2.0 reproduce: wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross chmod +x ~/bin/make.cross # save the attached .config to linux build tree GCC_VERSION=7.2.0 make.cross ARCH=arm64 All errors (new ones prefixed by >>): mm/migrate.c: In function 'migrate_misplaced_transhuge_page': >> mm/migrate.c:2054:32: error: 'end' undeclared (first use in this function); did you mean '_end'? flush_cache_range(vma, start, end + HPAGE_PMD_SIZE); ^~~ _end mm/migrate.c:2054:32: note: each undeclared identifier is reported only once for each function it appears in vim +2054 mm/migrate.c 2005 2006 #if defined(CONFIG_NUMA_BALANCING) && defined(CONFIG_TRANSPARENT_HUGEPAGE) 2007 /* 2008 * Migrates a THP to a given target node. page must be locked and is unlocked 2009 * before returning. 2010 */ 2011 int migrate_misplaced_transhuge_page(struct mm_struct *mm, 2012 struct vm_area_struct *vma, 2013 pmd_t *pmd, pmd_t entry, 2014 unsigned long address, 2015 struct page *page, int node) 2016 { 2017 spinlock_t *ptl; 2018 pg_data_t *pgdat = NODE_DATA(node); 2019 int isolated = 0; 2020 struct page *new_page = NULL; 2021 int page_lru = page_is_file_cache(page); 2022 unsigned long start = address & HPAGE_PMD_MASK; 2023 2024 /* 2025 * Rate-limit the amount of data that is being migrated to a node. 2026 * Optimal placement is no good if the memory bus is saturated and 2027 * all the time is being spent migrating! 2028 */ 2029 if (numamigrate_update_ratelimit(pgdat, HPAGE_PMD_NR)) 2030 goto out_dropref; 2031 2032 new_page = alloc_pages_node(node, 2033 (GFP_TRANSHUGE_LIGHT | __GFP_THISNODE), 2034 HPAGE_PMD_ORDER); 2035 if (!new_page) 2036 goto out_fail; 2037 prep_transhuge_page(new_page); 2038 2039 isolated = numamigrate_isolate_page(pgdat, page); 2040 if (!isolated) { 2041 put_page(new_page); 2042 goto out_fail; 2043 } 2044 2045 /* Prepare a page as a migration target */ 2046 __SetPageLocked(new_page); 2047 if (PageSwapBacked(page)) 2048 __SetPageSwapBacked(new_page); 2049 2050 /* anon mapping, we can simply copy page->mapping to the new page: */ 2051 new_page->mapping = page->mapping; 2052 new_page->index = page->index; 2053 /* flush the cache before copying using the kernel virtual address */ > 2054 flush_cache_range(vma, start, end + HPAGE_PMD_SIZE); 2055 migrate_page_copy(new_page, page); 2056 WARN_ON(PageLRU(new_page)); 2057 2058 /* Recheck the target PMD */ 2059 ptl = pmd_lock(mm, pmd); 2060 if (unlikely(!pmd_same(*pmd, entry) || !page_ref_freeze(page, 2))) { 2061 spin_unlock(ptl); 2062 2063 /* Reverse changes made by migrate_page_copy() */ 2064 if (TestClearPageActive(new_page)) 2065 SetPageActive(page); 2066 if (TestClearPageUnevictable(new_page)) 2067 SetPageUnevictable(page); 2068 2069 unlock_page(new_page); 2070 put_page(new_page); /* Free it */ 2071 2072 /* Retake the callers reference and putback on LRU */ 2073 get_page(page); 2074 putback_lru_page(page); 2075 mod_node_page_state(page_pgdat(page), 2076 NR_ISOLATED_ANON + page_lru, -HPAGE_PMD_NR); 2077 2078 goto out_unlock; 2079 } 2080 2081 entry = mk_huge_pmd(new_page, vma->vm_page_prot); 2082 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); 2083 2084 /* 2085 * Overwrite the old entry under pagetable lock and establish 2086 * the new PTE. Any parallel GUP will either observe the old 2087 * page blocking on the page lock, block on the page table 2088 * lock or observe the new page. The SetPageUptodate on the 2089 * new page and page_add_new_anon_rmap guarantee the copy is 2090 * visible before the pagetable update. 2091 */ 2092 page_add_anon_rmap(new_page, vma, start, true); 2093 /* 2094 * At this point the pmd is numa/protnone (i.e. non present) 2095 * and the TLB has already been flushed globally. So no TLB 2096 * can be currently caching this non present pmd mapping. 2097 * There's no need of clearing the pmd before doing 2098 * set_pmd_at(), nor to flush the TLB after 2099 * set_pmd_at(). Clearing the pmd here would introduce a race 2100 * condition against MADV_DONTNEED, beacuse MADV_DONTNEED only 2101 * holds the mmap_sem for reading. If the pmd is set to NULL 2102 * at any given time, MADV_DONTNEED won't wait on the pmd lock 2103 * and it'll skip clearing this pmd. 2104 */ 2105 set_pmd_at(mm, start, pmd, entry); 2106 update_mmu_cache_pmd(vma, address, &entry); 2107 2108 page_ref_unfreeze(page, 2); 2109 mlock_migrate_page(new_page, page); 2110 page_remove_rmap(page, true); 2111 set_page_owner_migrate_reason(new_page, MR_NUMA_MISPLACED); 2112 2113 spin_unlock(ptl); 2114 2115 /* Take an "isolate" reference and put new page on the LRU. */ 2116 get_page(new_page); 2117 putback_lru_page(new_page); 2118 2119 unlock_page(new_page); 2120 unlock_page(page); 2121 put_page(page); /* Drop the rmap reference */ 2122 put_page(page); /* Drop the LRU isolation reference */ 2123 2124 count_vm_events(PGMIGRATE_SUCCESS, HPAGE_PMD_NR); 2125 count_vm_numa_events(NUMA_PAGE_MIGRATE, HPAGE_PMD_NR); 2126 2127 mod_node_page_state(page_pgdat(page), 2128 NR_ISOLATED_ANON + page_lru, 2129 -HPAGE_PMD_NR); 2130 return isolated; 2131 2132 out_fail: 2133 count_vm_events(PGMIGRATE_FAIL, HPAGE_PMD_NR); 2134 out_dropref: 2135 ptl = pmd_lock(mm, pmd); 2136 if (pmd_same(*pmd, entry)) { 2137 entry = pmd_modify(entry, vma->vm_page_prot); 2138 set_pmd_at(mm, start, pmd, entry); 2139 update_mmu_cache_pmd(vma, address, &entry); 2140 } 2141 spin_unlock(ptl); 2142 2143 out_unlock: 2144 unlock_page(page); 2145 put_page(page); 2146 return 0; 2147 } 2148 #endif /* CONFIG_NUMA_BALANCING */ 2149 --- 0-DAY kernel test infrastructure Open Source Technology Center https://lists.01.org/pipermail/kbuild-all Intel Corporation
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