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[80.230.25.21]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4891c320084sm125739585e9.2.2026.04.20.05.50.53 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 20 Apr 2026 05:50:54 -0700 (PDT) Date: Mon, 20 Apr 2026 08:50:52 -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 , linux-mm@kvack.org, virtualization@lists.linux.dev, Lorenzo Stoakes , "Liam R. Howlett" , Mike Rapoport Subject: [PATCH RFC v2 12/18] mm: skip zeroing in alloc_anon_folio for pre-zeroed pages Message-ID: <97780c54dc083b9e3e0bfb4bb9ed7d8b1a576f91.1776689093.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 Use vma_alloc_folio_hints() and check PGHINT_ZEROED to skip folio_zero_user() in the mTHP anonymous page allocation path when the page is already zeroed. Signed-off-by: Michael S. Tsirkin Assisted-by: Claude:claude-opus-4-6 Assisted-by: cursor-agent:GPT-5.4-xhigh --- mm/memory.c | 14 +++++--------- 1 file changed, 5 insertions(+), 9 deletions(-) diff --git a/mm/memory.c b/mm/memory.c index c65e82c86fed..066e2c9781dc 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -5179,8 +5179,10 @@ static struct folio *alloc_anon_folio(struct vm_fault *vmf) /* Try allocating the highest of the remaining orders. */ gfp = vma_thp_gfp_mask(vma); while (orders) { + pghint_t hints; + addr = ALIGN_DOWN(vmf->address, PAGE_SIZE << order); - folio = vma_alloc_folio(gfp, order, vma, addr); + folio = vma_alloc_folio_hints(gfp, order, vma, addr, &hints); if (folio) { if (mem_cgroup_charge(folio, vma->vm_mm, gfp)) { count_mthp_stat(order, MTHP_STAT_ANON_FAULT_FALLBACK_CHARGE); @@ -5188,14 +5190,8 @@ static struct folio *alloc_anon_folio(struct vm_fault *vmf) goto next; } folio_throttle_swaprate(folio, gfp); - /* - * When a folio is not zeroed during allocation - * (__GFP_ZERO not used) or user folios require special - * handling, folio_zero_user() is used to make sure - * that the page corresponding to the faulting address - * will be hot in the cache after zeroing. - */ - if (user_alloc_needs_zeroing()) + if (user_alloc_needs_zeroing() && + !(hints & PGHINT_ZEROED)) folio_zero_user(folio, vmf->address); return folio; } -- MST