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[80.230.47.179]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-488fc10019bsm765744485e9.4.2026.04.26.14.47.47 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 26 Apr 2026 14:47:48 -0700 (PDT) Date: Sun, 26 Apr 2026 17:47:46 -0400 From: "Michael S. Tsirkin" To: linux-kernel@vger.kernel.org Cc: Andrew Morton , David Hildenbrand , Vlastimil Babka , Brendan Jackman , Michal Hocko , Suren Baghdasaryan , Jason Wang , Andrea Arcangeli , Gregory Price , linux-mm@kvack.org, virtualization@lists.linux.dev, Johannes Weiner , Zi Yan Subject: [PATCH RFC v4 05/22] mm: page_alloc: move prep_compound_page before post_alloc_hook Message-ID: <9c4c4cacb2cd5d1fd32219ab00f27e70600c3900.1777223007.git.mst@redhat.com> References: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Mailer: git-send-email 2.27.0.106.g8ac3dc51b1 X-Mutt-Fcc: =sent Move prep_compound_page() before post_alloc_hook() in prep_new_page(). The next patch adds a folio_zero_user() call to post_alloc_hook(), which uses folio_nr_pages() to determine how many pages to zero. Without compound metadata set up first, folio_nr_pages() returns 1 for higher-order allocations, so only the first page would be zeroed. All other operations in post_alloc_hook() (arch_alloc_page, KASAN, debug, page owner, etc.) use raw page pointers with explicit order counts and are unaffected by this reordering. Signed-off-by: Michael S. Tsirkin Assisted-by: Claude:claude-opus-4-6 Assisted-by: cursor-agent:GPT-5.4-xhigh --- mm/page_alloc.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/mm/page_alloc.c b/mm/page_alloc.c index c19eaf76607c..04c03c56abec 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -1895,11 +1895,11 @@ static void prep_new_page(struct page *page, unsigned int order, gfp_t gfp_flags unsigned int alloc_flags, unsigned long user_addr) { - post_alloc_hook(page, order, gfp_flags, user_addr); - if (order && (gfp_flags & __GFP_COMP)) prep_compound_page(page, order); + post_alloc_hook(page, order, gfp_flags, user_addr); + /* * page is set pfmemalloc when ALLOC_NO_WATERMARKS was necessary to * allocate the page. The expectation is that the caller is taking -- MST