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([120.133.49.20]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-856a2ea6fa3sm844230b3a.37.2026.08.28.11.37.31 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 28 Aug 2026 11:37:39 -0700 (PDT) From: Yin Tirui To: Andrew Morton , linux-mm@kvack.org Cc: David Hildenbrand , Lorenzo Stoakes , Dev Jain , Zi Yan , Baolin Wang , Barry Song , Lance Yang , Ryan Roberts , Nico Pache , Usama Arif , "Liam R . Howlett" , wangkefeng.wang@huawei.com, chenjun102@huawei.com, linux-kernel@vger.kernel.org, Yin Tirui Subject: [PATCH RFC 5/9] mm/huge_memory: dispatch on the folio when splitting a huge PMD Date: Sat, 29 Aug 2026 02:33:15 +0800 Message-Id: X-Mailer: git-send-email 2.34.1 In-Reply-To: References: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Only anonymous folios carry the anon rmap and PageAnonExclusive() state needed when rebuilding PTEs, so decide the split path from folio_test_anon() rather than vma_is_anonymous(). Treat a NULL folio as nothing to rebuild. This only changes behavior for folio/VMA mismatches, which are not produced by any in-tree path. Signed-off-by: Yin Tirui --- mm/huge_memory.c | 9 ++------- 1 file changed, 2 insertions(+), 7 deletions(-) diff --git a/mm/huge_memory.c b/mm/huge_memory.c index b2ede9a6ae5d..1cd8878edc1d 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -3244,7 +3244,7 @@ static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd, if (unlikely(!is_present && !folio)) return; - if (!vma_is_anonymous(vma)) { + if (!folio || !folio_test_anon(folio)) { unmap_huge_pmd_entry(vma, haddr, pmd, folio, is_present); return; } @@ -3254,14 +3254,12 @@ static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd, entry = softleaf_from_pmd(old_pmd); page = softleaf_to_page(entry); - folio = page_folio(page); soft_dirty = pmd_swp_soft_dirty(old_pmd); uffd_wp = pmd_swp_uffd(old_pmd); write = softleaf_is_migration_write(entry); - if (PageAnon(page)) - anon_exclusive = softleaf_is_migration_read_exclusive(entry); + anon_exclusive = softleaf_is_migration_read_exclusive(entry); young = softleaf_is_migration_young(entry); dirty = softleaf_is_migration_dirty(entry); } else if (pmd_is_device_private_entry(old_pmd)) { @@ -3269,7 +3267,6 @@ static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd, entry = softleaf_from_pmd(old_pmd); page = softleaf_to_page(entry); - folio = page_folio(page); soft_dirty = pmd_swp_soft_dirty(old_pmd); uffd_wp = pmd_swp_uffd(old_pmd); @@ -3321,7 +3318,6 @@ static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd, */ old_pmd = pmdp_invalidate(vma, haddr, pmd); page = pmd_page(old_pmd); - folio = page_folio(page); if (pmd_dirty(old_pmd)) { dirty = true; folio_set_dirty(folio); @@ -3332,7 +3328,6 @@ static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd, uffd_wp = pmd_uffd(old_pmd); VM_WARN_ON_FOLIO(!folio_ref_count(folio), folio); - VM_WARN_ON_FOLIO(!folio_test_anon(folio), folio); /* * Without "freeze", we'll simply split the PMD, propagating the -- 2.34.1