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b=PhV9mmVJj8HaWPabBYhvMSsgZMBm/iNmNrVKbOAwBrvBUDAS3kQzPqHIsoQoErIZ+ kUhMB7AiLoWxhuQwHEtRsLJ+TcYl/HFfQkIH0iosT9Vlfk/ZtkRrN7667NE1qNLDHA 3AWysrlhQkVoPGtjqmN2K0E1FN0qTC1lIjb5S6M3W7UXsmbTNfwG4r9hY0DDdOA4r9 39KEZ4ww4zwmSXesWcJRj8jYzQ6s5AlQXWTz5KJiYZ7+480u/c5Ev5cs/GMeJ6Ikl5 m+vjuqsmPW9pRo8g5Hx1mk/LubFTe1VuqHcmHEu7leARLCHxOafE/t+y+DHmEzvslm eEdS7mvZL1hnw== Message-ID: Date: Thu, 10 Sep 2026 09:50:26 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 03/11] mm/sparse-vmemmap: open-code init_compound_tail() To: Muchun Song , Andrew Morton , 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 , Randy Dunlap References: <20260908030335.96549-1-songmuchun@bytedance.com> <20260908030335.96549-4-songmuchun@bytedance.com> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 032AA1C0004 X-Stat-Signature: 39zdgz79f6m916ss5ykt9bddcksfenog X-Rspam-User: X-HE-Tag: 1789026805-374138 X-HE-Meta: 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 Pg/LVwM/ u5Xev+jlX1q79LOVkgBCN5wMjTGiIBzgZU1hx8cS352PGYh4bicwlZsOPJSJhawGf2dfW2QPcoUHMZtQvqs1R+iBqzJV8sPoFJA/6LccUwjTmfgIvV/vVkMyUr5aEIOZcuenv+S3umhmwbkUUT41qRj04tOTFaelMVG/9QEAlAugWh5bpWEktVGqhs4PZNMix+JkqcurhbWmJsysFisdTEvBBz5HOP6daE15MvMSKdJt6UYBkcVZnTgm6G/MQjyQdcoTmWV9oQWA33QW93YMmZsl7tPo1nkzyfJduuQBduLi4iHet3knnYx4d5+4IJmCXr08gKBgF1P9is1H+T+fg53O5fAD6UGSxx5NP Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 9/8/26 05:03, Muchun Song wrote: > 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 > --- > 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 70143dd8b579..e453ce4675a0 100644 > --- a/mm/sparse-vmemmap.c > +++ b/mm/sparse-vmemmap.c > @@ -189,7 +189,10 @@ 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); Acked-by: David Hildenbrand (Arm) -- Cheers, David