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Wed, 30 Sep 2026 07:07:50 -0700 (PDT) From: Muchun Song To: Andrew Morton , David Hildenbrand , Oscar Salvador , Madhavan Srinivasan , Michael Ellerman , Jonathan Corbet Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-doc@vger.kernel.org, Muchun Song , Lorenzo Stoakes , Mike Rapoport , Qi Zheng , Nicholas Piggin , Christophe Leroy , Ritesh Harjani , Shrikanth Hegde , Randy Dunlap , Muchun Song , Lance Yang Subject: [PATCH v6 04/12] mm/sparse-vmemmap: open-code init_compound_tail() Date: Wed, 30 Sep 2026 22:06:19 +0800 Message-ID: <20260930140627.57431-5-songmuchun@bytedance.com> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260930140627.57431-1-songmuchun@bytedance.com> References: <20260930140627.57431-1-songmuchun@bytedance.com> Precedence: bulk X-Mailing-List: linux-doc@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit init_compound_tail() is only used by vmemmap_shared_tail_page(), where the shared tail page setup intentionally passes NULL as the compound head. Keeping this helper in mm/internal.h exposes that special case to the rest of the MM code and can make the NULL head argument look generally valid. Open-code the initialization at the only call site so the special-case use stays local to sparse vmemmap optimization. No functional change intended. Signed-off-by: Muchun Song Acked-by: Qi Zheng Acked-by: David Hildenbrand (Arm) Acked-by: Mike Rapoport (Microsoft) --- v4: - Collect Acked-by from Mike Rapoport v3: - Collect Acked-by from David Hildenbrand v2: - Collect Acked-by from Qi Zheng --- mm/internal.h | 9 --------- mm/sparse-vmemmap.c | 5 ++++- 2 files changed, 4 insertions(+), 10 deletions(-) diff --git a/mm/internal.h b/mm/internal.h index da14c56fb24e..0dca33db068f 100644 --- a/mm/internal.h +++ b/mm/internal.h @@ -786,15 +786,6 @@ static inline void prep_compound_tail(struct page *tail, VM_WARN_ON_ONCE(tail->private); } -static inline void init_compound_tail(struct page *tail, - const struct page *head, unsigned int order, struct zone *zone) -{ - atomic_set(&tail->_mapcount, -1); - set_page_node(tail, zone_to_nid(zone)); - set_page_zone(tail, zone_idx(zone)); - prep_compound_tail(tail, head, order); -} - #if defined CONFIG_COMPACTION || defined CONFIG_CMA /* diff --git a/mm/sparse-vmemmap.c b/mm/sparse-vmemmap.c index 6916a3690778..f77e6e1e5a8b 100644 --- a/mm/sparse-vmemmap.c +++ b/mm/sparse-vmemmap.c @@ -221,7 +221,10 @@ struct page __ref *vmemmap_shared_tail_page(unsigned int order, struct zone *zon for (int i = 0; i < PAGE_SIZE / sizeof(struct page); i++) { page = (struct page *)addr + i; mm_zero_struct_page(page); - init_compound_tail(page, NULL, order, zone); + atomic_set(&page->_mapcount, -1); + set_page_node(page, zone_to_nid(zone)); + set_page_zone(page, zone_idx(zone)); + prep_compound_tail(page, NULL, order); } page = virt_to_page(addr); -- 2.54.0