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Thu, 05 Jan 2023 02:19:36 -0800 (PST) Date: Thu, 5 Jan 2023 10:18:27 +0000 In-Reply-To: <20230105101844.1893104-1-jthoughton@google.com> Mime-Version: 1.0 References: <20230105101844.1893104-1-jthoughton@google.com> X-Mailer: git-send-email 2.39.0.314.g84b9a713c41-goog Message-ID: <20230105101844.1893104-30-jthoughton@google.com> Subject: [PATCH 29/46] rmap: in try_to_{migrate,unmap}_one, check head page for page flags From: James Houghton To: Mike Kravetz , Muchun Song , Peter Xu Cc: David Hildenbrand , David Rientjes , Axel Rasmussen , Mina Almasry , "Zach O'Keefe" , Manish Mishra , Naoya Horiguchi , "Dr . David Alan Gilbert" , "Matthew Wilcox (Oracle)" , Vlastimil Babka , Baolin Wang , Miaohe Lin , Yang Shi , Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org, James Houghton Content-Type: text/plain; charset="UTF-8" X-Rspam-User: X-Rspamd-Queue-Id: 97B6340019 X-Rspamd-Server: rspam01 X-Stat-Signature: xzh4o8k16rid14gudqfz3h5jcoradi83 X-HE-Tag: 1672913977-465452 X-HE-Meta: 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 LmHvtxfp AF2WtyWDlnKTMpTCdsfw2m590RNDdvHWtnX0FG2Ozd2kimCHlIgwxyfc3BmpTuS2Uu9VIC8TYRHXSwFKSQ4yvpaLI1HjTrhw8RZE29RMCYlihtJgUXedn0qcEUa7vbFai3fQ39yqzSYSvD8jLrX5ecd7eOPL3lVsPg2+GUJ7EJVvkN0jVZzpVbQYo6rWXYPkyRxxn8EuWhO9Vvs81YA2DAhCuQxN+lH3jVs/qnj+L8NplxrAJ9znhfQLx0K9HOWo92IOs2QKT1SPlLyMJQhBGtStlb3RvJLauOvIu4Q1AbgIAAULPT0Iwk3hInulzBOh1fDyX5g7gmf352CfVgB9ciXoNUNmiipaG1OOnroD/YFwlA8HJ1F9AqneESu0oIr1TxhzjLd6F8o5tChbrEFuxU4jOyhUcZiNHYEj9o5W2utghzkk0Ki5yNKYpPpGcnbWjWQcj X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: The main complication here is that HugeTLB pages have their poison status stored in the head page as the HWPoison page flag. Because HugeTLB high-granularity mapping can create PTEs that point to subpages instead of always the head of a hugepage, we need to check the compound_head for page flags. Signed-off-by: James Houghton --- mm/rmap.c | 34 ++++++++++++++++++++++++++-------- 1 file changed, 26 insertions(+), 8 deletions(-) diff --git a/mm/rmap.c b/mm/rmap.c index 076ea77010e5..a6004d6b0415 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -1456,10 +1456,11 @@ static bool try_to_unmap_one(struct folio *folio, struct vm_area_struct *vma, struct mm_struct *mm = vma->vm_mm; DEFINE_FOLIO_VMA_WALK(pvmw, folio, vma, address, 0); pte_t pteval; - struct page *subpage; + struct page *subpage, *page_flags_page; bool anon_exclusive, ret = true; struct mmu_notifier_range range; enum ttu_flags flags = (enum ttu_flags)(long)arg; + bool page_poisoned; /* * When racing against e.g. zap_pte_range() on another cpu, @@ -1512,9 +1513,17 @@ static bool try_to_unmap_one(struct folio *folio, struct vm_area_struct *vma, subpage = folio_page(folio, pte_pfn(*pvmw.pte) - folio_pfn(folio)); + /* + * We check the page flags of HugeTLB pages by checking the + * head page. + */ + page_flags_page = folio_test_hugetlb(folio) + ? &folio->page + : subpage; + page_poisoned = PageHWPoison(page_flags_page); address = pvmw.address; anon_exclusive = folio_test_anon(folio) && - PageAnonExclusive(subpage); + PageAnonExclusive(page_flags_page); if (folio_test_hugetlb(folio)) { bool anon = folio_test_anon(folio); @@ -1523,7 +1532,7 @@ static bool try_to_unmap_one(struct folio *folio, struct vm_area_struct *vma, * The try_to_unmap() is only passed a hugetlb page * in the case where the hugetlb page is poisoned. */ - VM_BUG_ON_PAGE(!PageHWPoison(subpage), subpage); + VM_BUG_ON_FOLIO(!page_poisoned, folio); /* * huge_pmd_unshare may unmap an entire PMD page. * There is no way of knowing exactly which PMDs may @@ -1606,7 +1615,7 @@ static bool try_to_unmap_one(struct folio *folio, struct vm_area_struct *vma, /* Update high watermark before we lower rss */ update_hiwater_rss(mm); - if (PageHWPoison(subpage) && !(flags & TTU_IGNORE_HWPOISON)) { + if (page_poisoned && !(flags & TTU_IGNORE_HWPOISON)) { pteval = swp_entry_to_pte(make_hwpoison_entry(subpage)); if (folio_test_hugetlb(folio)) { hugetlb_count_sub(1UL << pvmw.pte_order, mm); @@ -1632,7 +1641,9 @@ static bool try_to_unmap_one(struct folio *folio, struct vm_area_struct *vma, mmu_notifier_invalidate_range(mm, address, address + PAGE_SIZE); } else if (folio_test_anon(folio)) { - swp_entry_t entry = { .val = page_private(subpage) }; + swp_entry_t entry = { + .val = page_private(page_flags_page) + }; pte_t swp_pte; /* * Store the swap location in the pte. @@ -1831,7 +1842,7 @@ static bool try_to_migrate_one(struct folio *folio, struct vm_area_struct *vma, struct mm_struct *mm = vma->vm_mm; DEFINE_FOLIO_VMA_WALK(pvmw, folio, vma, address, 0); pte_t pteval; - struct page *subpage; + struct page *subpage, *page_flags_page; bool anon_exclusive, ret = true; struct mmu_notifier_range range; enum ttu_flags flags = (enum ttu_flags)(long)arg; @@ -1911,9 +1922,16 @@ static bool try_to_migrate_one(struct folio *folio, struct vm_area_struct *vma, subpage = folio_page(folio, pte_pfn(*pvmw.pte) - folio_pfn(folio)); } + /* + * We check the page flags of HugeTLB pages by checking the + * head page. + */ + page_flags_page = folio_test_hugetlb(folio) + ? &folio->page + : subpage; address = pvmw.address; anon_exclusive = folio_test_anon(folio) && - PageAnonExclusive(subpage); + PageAnonExclusive(page_flags_page); if (folio_test_hugetlb(folio)) { bool anon = folio_test_anon(folio); @@ -2032,7 +2050,7 @@ static bool try_to_migrate_one(struct folio *folio, struct vm_area_struct *vma, * No need to invalidate here it will synchronize on * against the special swap migration pte. */ - } else if (PageHWPoison(subpage)) { + } else if (PageHWPoison(page_flags_page)) { pteval = swp_entry_to_pte(make_hwpoison_entry(subpage)); if (folio_test_hugetlb(folio)) { hugetlb_count_sub(1L << pvmw.pte_order, mm); -- 2.39.0.314.g84b9a713c41-goog