From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists.zx2c4.com (lists.zx2c4.com [165.227.139.114]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 00449CA100A for ; Mon, 1 Sep 2025 17:09:14 +0000 (UTC) Received: by lists.zx2c4.com (ZX2C4 Mail Server) with ESMTP id 48db9d15; Mon, 1 Sep 2025 15:14:02 +0000 (UTC) Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by lists.zx2c4.com (ZX2C4 Mail Server) with ESMTPS id 3d53be02 (TLSv1.3:TLS_AES_256_GCM_SHA384:256:NO) for ; Mon, 1 Sep 2025 15:13:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1756739635; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=jkEShtyZMAsDf/J3X4vsiABth2SEec0fiHHSpv4k9x8=; b=WKXsh5P+H1qNTNZkPhx7SE/4NliaZ1lT4nEt0Y0cMkzZyM3PV1gZejAZu7eWSvGAkh9orm fW8JkbHKDzxzXxE7fSS/525xgxAsEwgNFS6v820IWoV0Amddm3faXwi7CoiMBAkUEV7oq5 hu01y0ahMtIqckWvZxipvCWfQIXMuEk= Received: from mx-prod-mc-06.mail-002.prod.us-west-2.aws.redhat.com (ec2-35-165-154-97.us-west-2.compute.amazonaws.com [35.165.154.97]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-1-o2-TD6CtMRuqF-LwyESxUQ-1; Mon, 01 Sep 2025 11:13:51 -0400 X-MC-Unique: o2-TD6CtMRuqF-LwyESxUQ-1 X-Mimecast-MFC-AGG-ID: o2-TD6CtMRuqF-LwyESxUQ_1756739625 Received: from mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.93]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 4DA9F1800561; Mon, 1 Sep 2025 15:13:45 +0000 (UTC) Received: from t14s.fritz.box (unknown [10.22.88.45]) by mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id CF9891800447; Mon, 1 Sep 2025 15:13:30 +0000 (UTC) From: David Hildenbrand To: linux-kernel@vger.kernel.org Cc: David Hildenbrand , Marco Elver , Lorenzo Stoakes , Alexander Potapenko , Dmitry Vyukov , Andrew Morton , Brendan Jackman , Christoph Lameter , Dennis Zhou , 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, "Liam R. Howlett" , 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, Marek Szyprowski , Michal Hocko , Mike Rapoport , 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 35/37] kfence: drop nth_page() usage Date: Mon, 1 Sep 2025 17:03:56 +0200 Message-ID: <20250901150359.867252-36-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-BeenThere: wireguard@lists.zx2c4.com X-Mailman-Version: 2.1.30rc1 Precedence: list List-Id: Development discussion of WireGuard List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: wireguard-bounces@lists.zx2c4.com Sender: "WireGuard" We want to get rid of nth_page(), and kfence init code is the last user. Unfortunately, we might actually walk a PFN range where the pages are not contiguous, because we might be allocating an area from memblock that could span memory sections in problematic kernel configs (SPARSEMEM without SPARSEMEM_VMEMMAP). We could check whether the page range is contiguous using page_range_contiguous() and failing kfence init, or making kfence incompatible these problemtic kernel configs. Let's keep it simple and simply use pfn_to_page() by iterating PFNs. Reviewed-by: Marco Elver Reviewed-by: Lorenzo Stoakes Cc: Alexander Potapenko Cc: Dmitry Vyukov Signed-off-by: David Hildenbrand --- mm/kfence/core.c | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-) diff --git a/mm/kfence/core.c b/mm/kfence/core.c index 0ed3be100963a..727c20c94ac59 100644 --- a/mm/kfence/core.c +++ b/mm/kfence/core.c @@ -594,15 +594,14 @@ static void rcu_guarded_free(struct rcu_head *h) */ static unsigned long kfence_init_pool(void) { - unsigned long addr; - struct page *pages; + unsigned long addr, start_pfn; int i; if (!arch_kfence_init_pool()) return (unsigned long)__kfence_pool; addr = (unsigned long)__kfence_pool; - pages = virt_to_page(__kfence_pool); + start_pfn = PHYS_PFN(virt_to_phys(__kfence_pool)); /* * Set up object pages: they must have PGTY_slab set to avoid freeing @@ -613,11 +612,12 @@ static unsigned long kfence_init_pool(void) * enters __slab_free() slow-path. */ for (i = 0; i < KFENCE_POOL_SIZE / PAGE_SIZE; i++) { - struct slab *slab = page_slab(nth_page(pages, i)); + struct slab *slab; if (!i || (i % 2)) continue; + slab = page_slab(pfn_to_page(start_pfn + i)); __folio_set_slab(slab_folio(slab)); #ifdef CONFIG_MEMCG slab->obj_exts = (unsigned long)&kfence_metadata_init[i / 2 - 1].obj_exts | @@ -665,10 +665,12 @@ static unsigned long kfence_init_pool(void) reset_slab: for (i = 0; i < KFENCE_POOL_SIZE / PAGE_SIZE; i++) { - struct slab *slab = page_slab(nth_page(pages, i)); + struct slab *slab; if (!i || (i % 2)) continue; + + slab = page_slab(pfn_to_page(start_pfn + i)); #ifdef CONFIG_MEMCG slab->obj_exts = 0; #endif -- 2.50.1