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b=jghbsS5YSHe8w3LBrqGZUa9pzp MOYMpizHzLXjFvmjhQZ6oSg0Qx4tIOqknxI9s+KpUSUw/UN7qfWa2659QlI0d7pc8Q8IgqoFGDBew wIEJT+qqmadiV0iY/2GmP+dPJ0E+mN42rjdUE1Fz0qcBAlCvrqYA+ZEF+HwMIF9ZIQZ7Scnwe4tf8 XgWF/NKUshdj+uctNPhg8pJr0EmhoQV79evuxiU/rbJyCHOKuOH0ioAexDfSlJHpzl/XpBzTscROj RwhmhR0w9MCkIftqBi+uTo8Q702DSFkgVXaE/4FNrEaiVbeHTl+B6AClaBKyBiVe4ItgH/czc8BPE q0uQKcKw==; Received: from 114-44-196-209.dynamic-ip.hinet.net ([114.44.196.209] helo=gavin-HP-Z840-Workstation..) by fanzine2.igalia.com with esmtpsa (Cipher TLS1.3:ECDHE_X25519__RSA_PSS_RSAE_SHA256__AES_256_GCM:256) (Exim) id 1u8GT4-008HIu-8c; Fri, 25 Apr 2025 12:39:38 +0200 From: Gavin Guo To: linux-mm@kvack.org, akpm@linux-foundation.org Cc: gshan@redhat.com, david@redhat.com, willy@infradead.org, ziy@nvidia.com, linmiaohe@huawei.com, hughd@google.com, revest@google.com, kernel-dev@igalia.com, linux-kernel@vger.kernel.org Subject: [PATCH v2 1/2] mm/huge_memory: Adjust try_to_migrate_one() and split_huge_pmd_locked() Date: Fri, 25 Apr 2025 18:38:58 +0800 Message-ID: <20250425103859.825879-2-gavinguo@igalia.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20250425103859.825879-1-gavinguo@igalia.com> References: <20250425103859.825879-1-gavinguo@igalia.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Queue-Id: BB6A11C0006 X-Stat-Signature: zjjxfithxmt4yg4cthdpgt1ecdk9bqk7 X-Rspam-User: X-Rspamd-Server: rspam08 X-HE-Tag: 1745577580-72409 X-HE-Meta: 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 Cu0g/gRN 304ia8T2WxDQ8NKsh6mtLBCOJL2Hdhi4ElaMKEQL4Dw3U1Uq4KmyHIjKbZlNtHCHAYps4Fvp/8AlYXyASWGLV2ISmW1gY/naLfy97cpsJSDqPf3bePq5O/uL1/M5EzXtiYPmBbnVM5lm/z+n+c7Ssosiy/PqnxVtt2AFrIuabhI/oltxSfEzZVi68ZpZoEznT4zByI+7AmH+SNB+zr2yH5vO06RooAL2iLkaWRQzxi0ckr2jGGrHV/iqAaAMUQ6ZdOal+L9HCrt9JsfRIvkbyulWcFqITCCKjmQCZvIceTpmBJzdoOTywaU7+Yp9JXKdLzgbAdWIxLOr0ZyX4hI7nKzq4JyO5UbUSAg7txdbCgvUredYOCaClISVhBvwUSJDRbnqkcCRbQKEL6UmelDNoXNQX1OVB8uaRl0EB 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: The split_huge_pmd_locked function currently performs redundant checks for migration entries and folio validation that are already handled by the page_vma_mapped_walk mechanism in try_to_migrate_one. Specifically, page_vma_mapped_walk already ensures that: - The folio is properly mapped in the given VMA area - pmd_trans_huge, pmd_devmap, and migration entry validation are performed To leverage page_vma_mapped_walk's work, moving TTU_SPLIT_HUGE_PMD handling to the while loop checking and removing these duplicate checks from split_huge_pmd_locked. Suggested-by: David Hildenbrand Link: https://lore.kernel.org/all/98d1d195-7821-4627-b518-83103ade56c0@redhat.com/ Link: https://lore.kernel.org/all/91599a3c-e69e-4d79-bac5-5013c96203d7@redhat.com/ Signed-off-by: Gavin Guo Acked-by: David Hildenbrand --- mm/huge_memory.c | 21 ++------------------- mm/rmap.c | 18 +++++++++--------- 2 files changed, 11 insertions(+), 28 deletions(-) diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 47d76d03ce30..485a0ba011af 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -3075,27 +3075,10 @@ static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd, void split_huge_pmd_locked(struct vm_area_struct *vma, unsigned long address, pmd_t *pmd, bool freeze, struct folio *folio) { - bool pmd_migration = is_pmd_migration_entry(*pmd); - - VM_WARN_ON_ONCE(folio && !folio_test_pmd_mappable(folio)); VM_WARN_ON_ONCE(!IS_ALIGNED(address, HPAGE_PMD_SIZE)); - VM_WARN_ON_ONCE(folio && !folio_test_locked(folio)); - VM_BUG_ON(freeze && !folio); - - /* - * When the caller requests to set up a migration entry, we - * require a folio to check the PMD against. Otherwise, there - * is a risk of replacing the wrong folio. - */ - if (pmd_trans_huge(*pmd) || pmd_devmap(*pmd) || pmd_migration) { - /* - * Do not apply pmd_folio() to a migration entry; and folio lock - * guarantees that it must be of the wrong folio anyway. - */ - if (folio && (pmd_migration || folio != pmd_folio(*pmd))) - return; + if (pmd_trans_huge(*pmd) || pmd_devmap(*pmd) || + is_pmd_migration_entry(*pmd)) __split_huge_pmd_locked(vma, pmd, address, freeze); - } } void __split_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd, diff --git a/mm/rmap.c b/mm/rmap.c index 67bb273dfb80..b53a4dcaeaae 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -2291,13 +2291,6 @@ static bool try_to_migrate_one(struct folio *folio, struct vm_area_struct *vma, if (flags & TTU_SYNC) pvmw.flags = PVMW_SYNC; - /* - * unmap_page() in mm/huge_memory.c is the only user of migration with - * TTU_SPLIT_HUGE_PMD and it wants to freeze. - */ - if (flags & TTU_SPLIT_HUGE_PMD) - split_huge_pmd_address(vma, address, true, folio); - /* * For THP, we have to assume the worse case ie pmd for invalidation. * For hugetlb, it could be much worse if we need to do pud @@ -2323,9 +2316,16 @@ static bool try_to_migrate_one(struct folio *folio, struct vm_area_struct *vma, mmu_notifier_invalidate_range_start(&range); while (page_vma_mapped_walk(&pvmw)) { -#ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION /* PMD-mapped THP migration entry */ if (!pvmw.pte) { + if (flags & TTU_SPLIT_HUGE_PMD) { + split_huge_pmd_locked(vma, pvmw.address, + pvmw.pmd, true, NULL); + ret = false; + page_vma_mapped_walk_done(&pvmw); + break; + } +#ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION subpage = folio_page(folio, pmd_pfn(*pvmw.pmd) - folio_pfn(folio)); VM_BUG_ON_FOLIO(folio_test_hugetlb(folio) || @@ -2337,8 +2337,8 @@ static bool try_to_migrate_one(struct folio *folio, struct vm_area_struct *vma, break; } continue; - } #endif + } /* Unexpected PMD-mapped THP? */ VM_BUG_ON_FOLIO(!pvmw.pte, folio); -- 2.43.0