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[73.170.51.167]) by smtp.googlemail.com with ESMTPSA id t16-20020a17090b019000b002772faee740sm5162367pjs.5.2023.10.16.13.06.55 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 16 Oct 2023 13:06:56 -0700 (PDT) From: "Vishal Moola (Oracle)" To: linux-mm@kvack.org Cc: linux-kernel@vger.kernel.org, akpm@linux-foundation.org, shy828301@gmail.com, "Vishal Moola (Oracle)" , Matthew Wilcox Subject: [PATCH 1/5] mm/khugepaged: Convert __collapse_huge_page_isolate() to use folios Date: Mon, 16 Oct 2023 13:05:06 -0700 Message-Id: <20231016200510.7387-2-vishal.moola@gmail.com> X-Mailer: git-send-email 2.40.1 In-Reply-To: <20231016200510.7387-1-vishal.moola@gmail.com> References: <20231016200510.7387-1-vishal.moola@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" Replaces 11 calls to compound_head() with 1, and removes 1375 bytes of kernel text. Previously, to determine if any pte was shared, the page mapcount corresponding exactly to the pte was checked. This gave us a precise number of shared ptes. Using folio_estimated_sharers() instead uses the mapcount of the head page, giving us an estimate for tail page ptes. This means if a tail page's mapcount is greater than its head page's mapcount, folio_estimated_sharers() would be underestimating the number of shared ptes, and vice versa. Signed-off-by: Vishal Moola (Oracle) Reviewed-by: Matthew Wilcox (Oracle) --- mm/khugepaged.c | 51 ++++++++++++++++++++++++------------------------- 1 file changed, 25 insertions(+), 26 deletions(-) diff --git a/mm/khugepaged.c b/mm/khugepaged.c index 88433cc25d8a..7a552fe16c92 100644 --- a/mm/khugepaged.c +++ b/mm/khugepaged.c @@ -541,7 +541,7 @@ static int __collapse_huge_page_isolate(struct vm_area_= struct *vma, struct collapse_control *cc, struct list_head *compound_pagelist) { - struct page *page =3D NULL; + struct folio *folio =3D NULL; pte_t *_pte; int none_or_zero =3D 0, shared =3D 0, result =3D SCAN_FAIL, referenced = =3D 0; bool writable =3D false; @@ -570,15 +570,15 @@ static int __collapse_huge_page_isolate(struct vm_are= a_struct *vma, result =3D SCAN_PTE_UFFD_WP; goto out; } - page =3D vm_normal_page(vma, address, pteval); - if (unlikely(!page) || unlikely(is_zone_device_page(page))) { + folio =3D vm_normal_folio(vma, address, pteval); + if (unlikely(!folio) || unlikely(folio_is_zone_device(folio))) { result =3D SCAN_PAGE_NULL; goto out; } =20 - VM_BUG_ON_PAGE(!PageAnon(page), page); + VM_BUG_ON_FOLIO(!folio_test_anon(folio), folio); =20 - if (page_mapcount(page) > 1) { + if (folio_estimated_sharers(folio) > 1) { ++shared; if (cc->is_khugepaged && shared > khugepaged_max_ptes_shared) { @@ -588,16 +588,15 @@ static int __collapse_huge_page_isolate(struct vm_are= a_struct *vma, } } =20 - if (PageCompound(page)) { - struct page *p; - page =3D compound_head(page); + if (folio_test_large(folio)) { + struct folio *f; =20 /* * Check if we have dealt with the compound page * already */ - list_for_each_entry(p, compound_pagelist, lru) { - if (page =3D=3D p) + list_for_each_entry(f, compound_pagelist, lru) { + if (folio =3D=3D f) goto next; } } @@ -608,7 +607,7 @@ static int __collapse_huge_page_isolate(struct vm_area_= struct *vma, * is needed to serialize against split_huge_page * when invoked from the VM. */ - if (!trylock_page(page)) { + if (!folio_trylock(folio)) { result =3D SCAN_PAGE_LOCK; goto out; } @@ -624,8 +623,8 @@ static int __collapse_huge_page_isolate(struct vm_area_= struct *vma, * but not from this process. The other process cannot write to * the page, only trigger CoW. */ - if (!is_refcount_suitable(page)) { - unlock_page(page); + if (!is_refcount_suitable(&folio->page)) { + folio_unlock(folio); result =3D SCAN_PAGE_COUNT; goto out; } @@ -634,27 +633,27 @@ static int __collapse_huge_page_isolate(struct vm_are= a_struct *vma, * Isolate the page to avoid collapsing an hugepage * currently in use by the VM. */ - if (!isolate_lru_page(page)) { - unlock_page(page); + if (!folio_isolate_lru(folio)) { + folio_unlock(folio); result =3D SCAN_DEL_PAGE_LRU; goto out; } - mod_node_page_state(page_pgdat(page), - NR_ISOLATED_ANON + page_is_file_lru(page), - compound_nr(page)); - VM_BUG_ON_PAGE(!PageLocked(page), page); - VM_BUG_ON_PAGE(PageLRU(page), page); + node_stat_mod_folio(folio, + NR_ISOLATED_ANON + folio_is_file_lru(folio), + folio_nr_pages(folio)); + VM_BUG_ON_FOLIO(!folio_test_locked(folio), folio); + VM_BUG_ON_FOLIO(folio_test_lru(folio), folio); =20 - if (PageCompound(page)) - list_add_tail(&page->lru, compound_pagelist); + if (folio_test_large(folio)) + list_add_tail(&folio->lru, compound_pagelist); next: /* * If collapse was initiated by khugepaged, check that there is * enough young pte to justify collapsing the page */ if (cc->is_khugepaged && - (pte_young(pteval) || page_is_young(page) || - PageReferenced(page) || mmu_notifier_test_young(vma->vm_mm, + (pte_young(pteval) || folio_test_young(folio) || + folio_test_referenced(folio) || mmu_notifier_test_young(vma->vm_mm, address))) referenced++; =20 @@ -668,13 +667,13 @@ static int __collapse_huge_page_isolate(struct vm_are= a_struct *vma, result =3D SCAN_LACK_REFERENCED_PAGE; } else { result =3D SCAN_SUCCEED; - trace_mm_collapse_huge_page_isolate(page, none_or_zero, + trace_mm_collapse_huge_page_isolate(&folio->page, none_or_zero, referenced, writable, result); return result; } out: release_pte_pages(pte, _pte, compound_pagelist); - trace_mm_collapse_huge_page_isolate(page, none_or_zero, + trace_mm_collapse_huge_page_isolate(&folio->page, none_or_zero, referenced, writable, result); return result; } --=20 2.40.1