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Howlett" , Linus Torvalds , linux-arm-kernel@axis.com, linux-arm-kernel@lists.infradead.org, linux-crypto@vger.kernel.org, linux-ide@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-mips@vger.kernel.org, linux-mmc@vger.kernel.org, linux-mm@kvack.org, linux-riscv@lists.infradead.org, linux-s390@vger.kernel.org, linux-scsi@vger.kernel.org, Lorenzo Stoakes , Marco Elver , Marek Szyprowski , Michal Hocko , Muchun Song , netdev@vger.kernel.org, Oscar Salvador , Peter Xu , Robin Murphy , Suren Baghdasaryan , Tejun Heo , virtualization@lists.linux.dev, Vlastimil Babka , wireguard@lists.zx2c4.com, x86@kernel.org, Zi Yan Subject: [PATCH v1 09/36] mm/mm_init: make memmap_init_compound() look more like prep_compound_page() Date: Thu, 28 Aug 2025 00:01:13 +0200 Message-ID: <20250827220141.262669-10-david@redhat.com> In-Reply-To: <20250827220141.262669-1-david@redhat.com> References: <20250827220141.262669-1-david@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.4 X-Rspamd-Queue-Id: A5F3418000F X-Rspam-User: X-Stat-Signature: 6q1rs4b1a7zjhdqnqk3hkk3e5ygj1p3w X-Rspamd-Server: rspam09 X-HE-Tag: 1756332302-909129 X-HE-Meta: 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 DOCIyGyu 4kgSRFZQxnF8/HPM756IkHgpc3kTOf62MOryKYIHUR6cxyZIbFsYBt9ZmHMaHLyhJvsSzmNVL4Tv9Rn0EsRMcJXj4BWbtue18FCPReCEmMPfaDOnTlUZPcH+EHhAXNAfbs629UnYaIKfpQvDxvfw0mcK3Srszz/1ZrLqYEuvjrmYz9qAJdkJX3QMoi2IIz4c7t9r1RaKgTvJiZOJk4UMjVQ/AczZYxHuIAb8cghX5Tmq/HheTGk+ZiJohiSadrUAls1l6uFQGpq6pFnmJ+7+8mX6FwPnfELev4NTtJTJq91910859J4OY4Xpvzi/wH0ZofPX6s0lTFBWmu4xenlpx+UG/QyA5+YVPKtxZwqGLoY/qBKP3+12dMA8vsJ851Kv5ZuEu+XoMloZaNUdW+mo+zcLGpg== 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: Grepping for "prep_compound_page" leaves on clueless how devdax gets its compound pages initialized. Let's add a comment that might help finding this open-coded prep_compound_page() initialization more easily. Further, let's be less smart about the ordering of initialization and just perform the prep_compound_head() call after all tail pages were initialized: just like prep_compound_page() does. No need for a comment to describe the initialization order: again, just like prep_compound_page(). Reviewed-by: Mike Rapoport (Microsoft) Signed-off-by: David Hildenbrand --- mm/mm_init.c | 15 +++++++-------- 1 file changed, 7 insertions(+), 8 deletions(-) diff --git a/mm/mm_init.c b/mm/mm_init.c index 5c21b3af216b2..df614556741a4 100644 --- a/mm/mm_init.c +++ b/mm/mm_init.c @@ -1091,6 +1091,12 @@ static void __ref memmap_init_compound(struct page *head, unsigned long pfn, end_pfn = head_pfn + nr_pages; unsigned int order = pgmap->vmemmap_shift; + /* + * We have to initialize the pages, including setting up page links. + * prep_compound_page() does not take care of that, so instead we + * open-code prep_compound_page() so we can take care of initializing + * the pages in the same go. + */ __SetPageHead(head); for (pfn = head_pfn + 1; pfn < end_pfn; pfn++) { struct page *page = pfn_to_page(pfn); @@ -1098,15 +1104,8 @@ static void __ref memmap_init_compound(struct page *head, __init_zone_device_page(page, pfn, zone_idx, nid, pgmap); prep_compound_tail(head, pfn - head_pfn); set_page_count(page, 0); - - /* - * The first tail page stores important compound page info. - * Call prep_compound_head() after the first tail page has - * been initialized, to not have the data overwritten. - */ - if (pfn == head_pfn + 1) - prep_compound_head(head, order); } + prep_compound_head(head, order); } void __ref memmap_init_zone_device(struct zone *zone, -- 2.50.1