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Wed, 20 Dec 2023 22:45:10 +0000 (UTC) From: David Hildenbrand To: linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org, David Hildenbrand , Andrew Morton , "Matthew Wilcox (Oracle)" , Hugh Dickins , Ryan Roberts , Yin Fengwei , Mike Kravetz , Muchun Song , Peter Xu Subject: [PATCH v2 02/40] mm/rmap: introduce and use hugetlb_remove_rmap() Date: Wed, 20 Dec 2023 23:44:26 +0100 Message-ID: <20231220224504.646757-3-david@redhat.com> In-Reply-To: <20231220224504.646757-1-david@redhat.com> References: <20231220224504.646757-1-david@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.2 X-Rspamd-Queue-Id: 04C6A180002 X-Rspam-User: X-Stat-Signature: 83edw69qxwrjrm43pphoidoart9wixku X-Rspamd-Server: rspam01 X-HE-Tag: 1703112317-15527 X-HE-Meta: U2FsdGVkX1+OW3tE1wMI3nA4LKhJM4n6lOMrWpZFYTBP4RhkJOvN2KtJ0kRZkz2VAwZpj1M5EMr3vyT8lh0zSvbKpHK7ShxSJctJRkKA4hU8aSUd6FnGqhYgw8jhdPGWZLwIpsuQTrs72sgsvZS1LFYcCECMtMYmNjcqS+qqnxC4OGn2MJHCbJwKQj6RghYfbNO+DKD9DK4Nl0xk6HYbSy4Uhhha18TbLa+3RfgDbdqcFCDP6TqhdBLowHqR1XHYxTbchlmHuO9P+N1OAcQhZOPnLBTCnKvrgO3avXd9bAB+oUADziXLgbJbkl/JYelrZiVwKIttrx+Tuhd1XuYAQwEzRuoWUfB9IfIBKH//ZQTrVhsh74PSVSK7RUhBBJyjLsXEZ1XwlEC0jO7w9EwpdboL7YixAc5iEg2GVLxTP2EyjDXIz6J2CajZFcMjEpaKCGW6pI9KaQjAj1zbpkKf2e3rNIea7kGDMy1OxomUpMNmZ0b2oJyt833Vb1GRU/8wTKqToKkSlS2xWHQL77K6H86zNT+XfuE5fEIZKOMRtyNWfq7rvUrlmqzKZQS6QgE3vEooRwUDUTy7lL0Z0by/sWgr0s9SMmekjXTVm+dtvK56M2AZ2Mi6c0lST4U4l395Fb0hfJTf33Bv5uXsBNsOfdAWOUBMElrvtRwoPiCQ+4yAlMeu0rYqIrHiAUucRusbrxdUZYNYS7P3oCxtEHpmEHxoCH/D1jr/aeGF0y2mcf3p97rcnCKRcHAcHz4oV/4pqOS7f1k8+aQYvPPAaouSX5z+vPurZcqttTuOMKzvsZon8RFapmZw+FMfo9D0xAQoZinlc/r5QCVI8Std/KI3v3O8kATYR++vvcv2JsKScNvYbOLmUrsZLk1N19BvmcnRIQjk3Yx1Wy8Hy9ZGW7UOcdtxFEsqSa3zNJdv1AMoOlkFUxzrxV0Jh6EKTkZbnZOJE7kf7rwoVYEM74EeLfp fFBV48B0 1gmy3W3zJeLeO7Zr1ZBJ0TuIWEtmo5mFhGgaubg0dULnAa8yFcoz82KCcb5M8gCnMDARNS+WNSDu48iPE/0mY4D47F0BvpyaQP0ju3EIPkNSgwzKA6bLYe9efgC1SWsdmBn5nS9UK/fe2fDqrYvA22Zy/JCMQEjuF9XyD4EJflkDc9R2d/8DfzneNzwYvSwdZbetdpcRNcXyF7LsV1XedUhVk+BEFratvl7RVHi+mKdzsS9MTxZVjYmsBj7GmZ/VN+3foZmEJLrf212M+tCUxKBjWDGK21/HRiLgXR+F+Vi8BXUnFHYTZ44PcF2uIVRc01hNOvM9e5CL23/j/uVgTfOGavwWdPHEAOhsE2ErqsqmcT14= 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: List-Subscribe: List-Unsubscribe: hugetlb rmap handling differs quite a lot from "ordinary" rmap code. For example, hugetlb currently only supports entire mappings, and treats any mapping as mapped using a single "logical PTE". Let's move it out of the way so we can overhaul our "ordinary" rmap. implementation/interface. Let's introduce and use hugetlb_remove_rmap() and remove the hugetlb code from page_remove_rmap(). This effectively removes one check on the small-folio path as well. Add sanity checks that we end up with the right folios in the right functions. Note: all possible candidates that need care are page_remove_rmap() that pass compound=true. Reviewed-by: Yin Fengwei Reviewed-by: Ryan Roberts Reviewed-by: Matthew Wilcox (Oracle) Signed-off-by: David Hildenbrand Reviewed-by: Muchun Song --- include/linux/rmap.h | 7 +++++++ mm/hugetlb.c | 4 ++-- mm/rmap.c | 18 +++++++++--------- 3 files changed, 18 insertions(+), 11 deletions(-) diff --git a/include/linux/rmap.h b/include/linux/rmap.h index 36096ba69bdcd..64ae6c4d72720 100644 --- a/include/linux/rmap.h +++ b/include/linux/rmap.h @@ -211,6 +211,13 @@ void hugetlb_add_anon_rmap(struct folio *, struct vm_area_struct *, void hugetlb_add_new_anon_rmap(struct folio *, struct vm_area_struct *, unsigned long address); +static inline void hugetlb_remove_rmap(struct folio *folio) +{ + VM_WARN_ON_FOLIO(!folio_test_hugetlb(folio), folio); + + atomic_dec(&folio->_entire_mapcount); +} + static inline void __page_dup_rmap(struct page *page, bool compound) { if (compound) { diff --git a/mm/hugetlb.c b/mm/hugetlb.c index 305f3ca1dee62..ef48ae6738909 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -5676,7 +5676,7 @@ void __unmap_hugepage_range(struct mmu_gather *tlb, struct vm_area_struct *vma, make_pte_marker(PTE_MARKER_UFFD_WP), sz); hugetlb_count_sub(pages_per_huge_page(h), mm); - page_remove_rmap(page, vma, true); + hugetlb_remove_rmap(page_folio(page)); spin_unlock(ptl); tlb_remove_page_size(tlb, page, huge_page_size(h)); @@ -5987,7 +5987,7 @@ static vm_fault_t hugetlb_wp(struct mm_struct *mm, struct vm_area_struct *vma, /* Break COW or unshare */ huge_ptep_clear_flush(vma, haddr, ptep); - page_remove_rmap(&old_folio->page, vma, true); + hugetlb_remove_rmap(old_folio); hugetlb_add_new_anon_rmap(new_folio, vma, haddr); if (huge_pte_uffd_wp(pte)) newpte = huge_pte_mkuffd_wp(newpte); diff --git a/mm/rmap.c b/mm/rmap.c index 9845499b22f8f..261e1af0d254f 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -1480,15 +1480,9 @@ void page_remove_rmap(struct page *page, struct vm_area_struct *vma, bool last; enum node_stat_item idx; + VM_WARN_ON_FOLIO(folio_test_hugetlb(folio), folio); VM_BUG_ON_PAGE(compound && !PageHead(page), page); - /* Hugetlb pages are not counted in NR_*MAPPED */ - if (unlikely(folio_test_hugetlb(folio))) { - /* hugetlb pages are always mapped with pmds */ - atomic_dec(&folio->_entire_mapcount); - return; - } - /* Is page being unmapped by PTE? Is this its last map to be removed? */ if (likely(!compound)) { last = atomic_add_negative(-1, &page->_mapcount); @@ -1846,7 +1840,10 @@ static bool try_to_unmap_one(struct folio *folio, struct vm_area_struct *vma, dec_mm_counter(mm, mm_counter_file(&folio->page)); } discard: - page_remove_rmap(subpage, vma, folio_test_hugetlb(folio)); + if (unlikely(folio_test_hugetlb(folio))) + hugetlb_remove_rmap(folio); + else + page_remove_rmap(subpage, vma, false); if (vma->vm_flags & VM_LOCKED) mlock_drain_local(); folio_put(folio); @@ -2199,7 +2196,10 @@ static bool try_to_migrate_one(struct folio *folio, struct vm_area_struct *vma, */ } - page_remove_rmap(subpage, vma, folio_test_hugetlb(folio)); + if (unlikely(folio_test_hugetlb(folio))) + hugetlb_remove_rmap(folio); + else + page_remove_rmap(subpage, vma, false); if (vma->vm_flags & VM_LOCKED) mlock_drain_local(); folio_put(folio);