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[80.230.25.21]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-43fe4e4daf2sm28270624f8f.33.2026.04.20.05.50.56 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 20 Apr 2026 05:50:57 -0700 (PDT) Date: Mon, 20 Apr 2026 08:50:55 -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 , Zi Yan , Baolin Wang , "Liam R. Howlett" , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Lance Yang Subject: [PATCH RFC v2 13/18] mm: skip zeroing in vma_alloc_anon_folio_pmd for pre-zeroed pages Message-ID: <551567632643dc1b5cdf08284039aeba0b296b6d.1776689093.git.mst@redhat.com> References: MIME-Version: 1.0 In-Reply-To: X-Mailer: git-send-email 2.27.0.106.g8ac3dc51b1 X-Mutt-Fcc: =sent X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: uBpTsxSRSeWc9XOP_xgIIA9mzngHY1yCEX4xTyHIBdI_1776689459 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Disposition: inline X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: 277151C0009 X-Stat-Signature: 5crz3ixqsddermqdce5pyrrq343ctx8j X-Rspam-User: X-HE-Tag: 1776689462-186123 X-HE-Meta: U2FsdGVkX1+8XguqA85rf6FVvkTQ7e6J4ugfjxYAcC+mwiFufL2zriqTwjsR6tITBbh+sl2TouCwQ5xz39FcCc8VicxUZWiL5/7nvtw2L+82ZthD1QaBJ77zbTmKy2F2i953pA2bHX6IvhP1EOktj47M1gXSSb9qSPk/iCtGMXKZIkvc/zlz7BXDka0ZQqe6hfM9gi0RDwnvrEVSv5+J6ygUpMwj9YM7BaYrtIZLgD4dcmRDRn+GGR5iCR5NHA/MBj4Cx6KJItkzue5CEy21pxqvjdEOfPTinI1dBs91OVr4/aGXuZzTg1eKvoFJu0AuN1xzXd4zuy4tv3ghT91gYuKw62psHJQiWy1eObn0tJW2ie2nMhY5JkdDER5rZel7R6qz19a4BxMO5x1YKbQmjwjcnGUiu732vJe05bSZwbCVS5ZYrmqBsFKxHPalS9b3X4I+T/N/VuZYjPNXg2axqTPO0crZmxLHFd+v9n6tT/3iriM/btrCbwuLIt05bMcxDk3JtJZdj1t/2YU7h0s2KIjym4jzg5SKgOi73iP5Ff4ghdOWy+ZXPvZYZkj64usj7JnTb4pkXgA5YrlhvVyym8XkXdwZvPKHWQtpM2akye3MzyKngi6kLYzJQpd3rA5vB//+j75MDU2TlA1tz5O4lK+ayTrU8WbtfRdxEbrULAiIsha+x6Ra2XeRrcibir5X+d3RUp4R1DDtiktZBCCnm/9s/YoozkyKi5np41RRrJr3oWeIJvjmYVcf9xE1gUkE3jRX2MXM5v/+Dud2nGH19pQPjRn8GZJWxDeR1Q61zgkUz3RvMhZVIs0aQCLiHAfKJh3PyS0bu10k/oSCb9HJjh5uunITzQLiwPEiquZa+xfxDcalSfUBNER0wEu0KncTz6vFJaOqMtFYfDPoZ9AzEihEVf04Cj3xqo4FGkr+VdEG/S/NnGyynl8KYMro0SrY+XhS/QYsifXx2OvKIQp D9kNiZnK WKwMZZZA+UJwiz+w3aOUL9xIIHGtHJ/jS1pzLvi3buZDXukvV0EAd0xMWV+1ym5+2MoKgH6ROSJ8JyAssmz+19ILg/RjXmK20gcPnTq0acDEijaq9Ww2Y1XoGcQ5ZGCzWVnSaLF3naFoxnLpnxRojFQDPaa4DGvUvTCyYwIBYeNgLqVP90onMy74QiE7td7GUEnngZYE2ftqXKjLGkvomUoE3I9lHhui+MidCmwWF/Kcg6KtMROVkp1XBMbBV2DNZBBkfFSMSvG5Carb/02hAWHIpJWV/NrUmrvACvKeL761X90o3nDEZBJ76gxG6os3Pra16eR90rU4P9bQjta7ZOdPl/HKTpYvk7vl5CzZzs8Vp0oVa4FIdS//qsA== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Use vma_alloc_folio_hints() and check PGHINT_ZEROED to skip folio_zero_user() in the PMD THP 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/huge_memory.c | 12 ++++-------- 1 file changed, 4 insertions(+), 8 deletions(-) diff --git a/mm/huge_memory.c b/mm/huge_memory.c index b298cba853ab..243592452ead 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -1259,8 +1259,10 @@ static struct folio *vma_alloc_anon_folio_pmd(struct vm_area_struct *vma, gfp_t gfp = vma_thp_gfp_mask(vma); const int order = HPAGE_PMD_ORDER; struct folio *folio; + pghint_t hints; - folio = vma_alloc_folio(gfp, order, vma, addr & HPAGE_PMD_MASK); + folio = vma_alloc_folio_hints(gfp, order, vma, addr & HPAGE_PMD_MASK, + &hints); if (unlikely(!folio)) { count_vm_event(THP_FAULT_FALLBACK); @@ -1279,13 +1281,7 @@ static struct folio *vma_alloc_anon_folio_pmd(struct vm_area_struct *vma, } 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, addr); /* * The memory barrier inside __folio_mark_uptodate makes sure that -- MST