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Howlett" , Alexander Potapenko , Andrew Morton , Brendan Jackman , Christoph Lameter , Dennis Zhou , Dmitry Vyukov , dri-devel@lists.freedesktop.org, intel-gfx@lists.freedesktop.org, iommu@lists.linux.dev, io-uring@vger.kernel.org, Jason Gunthorpe , Jens Axboe , Johannes Weiner , John Hubbard , kasan-dev@googlegroups.com, kvm@vger.kernel.org, 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, 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 v2 09/37] mm/mm_init: make memmap_init_compound() look more like prep_compound_page() Date: Mon, 1 Sep 2025 17:03:30 +0200 Message-ID: <20250901150359.867252-10-david@redhat.com> In-Reply-To: <20250901150359.867252-1-david@redhat.com> References: <20250901150359.867252-1-david@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.93 X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 90DD318000A X-Stat-Signature: 8ajobnnrf3ohnr9qgdp35m3dqki9wu4s X-Rspam-User: X-HE-Tag: 1756739230-804910 X-HE-Meta: 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 hEJ+s+/g 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 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) Reviewed-by: Wei Yang Reviewed-by: Lorenzo Stoakes Acked-by: Liam R. Howlett 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