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Thu, 23 Apr 2026 00:19:20 -0700 (PDT) From: Muchun Song To: Andrew Morton , David Hildenbrand , Muchun Song , Oscar Salvador , Michael Ellerman , Madhavan Srinivasan Cc: Lorenzo Stoakes , "Liam R . Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Nicholas Piggin , Christophe Leroy , aneesh.kumar@linux.ibm.com, joao.m.martins@oracle.com, linux-mm@kvack.org, linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, Muchun Song Subject: [PATCH v5 0/6] mm: fix vmemmap optimization accounting and initialization Date: Thu, 23 Apr 2026 15:19:05 +0800 Message-Id: <20260423071911.1962859-1-songmuchun@bytedance.com> X-Mailer: git-send-email 2.20.1 X-Mailing-List: linuxppc-dev@lists.ozlabs.org List-Id: List-Help: List-Owner: List-Post: List-Archive: , List-Subscribe: , , List-Unsubscribe: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit The series fixes several bugs in vmemmap optimization, mainly around incorrect page accounting and memmap initialization in DAX and memory hotplug paths. It also fixes pageblock migratetype initialization and struct page initialization for ZONE_DEVICE compound pages. The first four patches fix vmemmap accounting issues. The first patch fixes an accounting underflow in the section activation failure path. The second patch fixes incorrect altmap passing in the error path. The third patch passes pgmap through memory deactivation paths so the teardown side can determine whether vmemmap optimization was in effect. The fourth patch uses that information to account the optimized DAX vmemmap size correctly. The last two patches fix initialization issues in mm/mm_init. One makes sure all pageblocks in ZONE_DEVICE compound pages get their migratetype initialized. The other fixes a case where DAX memory hotplug reuses an unoptimized early-section memmap while compound_nr_pages() still assumes vmemmap optimization, leaving tail struct pages uninitialized. Changelog: v4 -> v5: - mm/memory_hotplug: Fix incorrect altmap passing in error path (new bugfix suggested by Sashiko). - mm/sparse-vmemmap: Rename section_vmemmap_pages() to section_nr_vmemmap_pages() and use two-tab indent (suggested by David). - mm/sparse-vmemmap: Use 1UL for pages_per_compound and use const for order and pages_per_compound (suggested by David). - mm/sparse-vmemmap: Simplify VM_WARN_ON_ONCE checks for better readability (suggested by David). - mm/mm_init: Use two-tab indent and const for @end in pageblock_migratetype_init_range() (suggested by David). - Collect Acked-by tags from David. Muchun Song (6): mm/sparse-vmemmap: Fix vmemmap accounting underflow mm/memory_hotplug: Fix incorrect altmap passing in error path mm/sparse-vmemmap: Pass @pgmap argument to memory deactivation paths mm/sparse-vmemmap: Fix DAX vmemmap accounting with optimization mm/mm_init: Fix pageblock migratetype for ZONE_DEVICE compound pages mm/mm_init: Fix uninitialized struct pages for ZONE_DEVICE arch/arm64/mm/mmu.c | 5 +-- arch/loongarch/mm/init.c | 5 +-- arch/powerpc/mm/mem.c | 5 +-- arch/riscv/mm/init.c | 5 +-- arch/s390/mm/init.c | 5 +-- arch/x86/mm/init_64.c | 5 +-- include/linux/memory_hotplug.h | 6 +-- mm/memory_hotplug.c | 15 ++++---- mm/memremap.c | 4 +- mm/mm_init.c | 34 +++++++++------- mm/sparse-vmemmap.c | 37 ++++++++++++++---- 11 files changed, 81 insertions(+), 45 deletions(-) -- 2.20.1