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[80.230.25.21]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-488fb735d3dsm184142605e9.2.2026.04.20.05.50.59 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 20 Apr 2026 05:51:00 -0700 (PDT) Date: Mon, 20 Apr 2026 08:50:58 -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, Hugh Dickins , Baolin Wang Subject: [PATCH RFC v2 14/18] mm: memfd: skip zeroing for pre-zeroed hugetlb pages Message-ID: <03405f0008afd371021e98a985490dce7fab6e7d.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 the pghint_t output from alloc_hugetlb_folio_reserve() to skip folio_zero_user() 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/memfd.c | 12 ++++-------- 1 file changed, 4 insertions(+), 8 deletions(-) diff --git a/mm/memfd.c b/mm/memfd.c index f1c00600e19a..546149897369 100644 --- a/mm/memfd.c +++ b/mm/memfd.c @@ -81,6 +81,7 @@ struct folio *memfd_alloc_folio(struct file *memfd, pgoff_t idx) struct hstate *h = hstate_file(memfd); int err = -ENOMEM; long nr_resv; + pghint_t hints; gfp_mask = htlb_alloc_mask(h); gfp_mask &= ~(__GFP_HIGHMEM | __GFP_MOVABLE); @@ -93,17 +94,12 @@ struct folio *memfd_alloc_folio(struct file *memfd, pgoff_t idx) folio = alloc_hugetlb_folio_reserve(h, numa_node_id(), NULL, - gfp_mask, NULL); + gfp_mask, &hints); if (folio) { u32 hash; - /* - * Zero the folio to prevent information leaks to userspace. - * Use folio_zero_user() which is optimized for huge/gigantic - * pages. Pass 0 as addr_hint since this is not a faulting path - * and we don't have a user virtual address yet. - */ - folio_zero_user(folio, 0); + if (!(hints & PGHINT_ZEROED)) + folio_zero_user(folio, 0); /* * Mark the folio uptodate before adding to page cache, -- MST