From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 3A5633064BE for ; Mon, 1 Sep 2025 15:13:54 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.129.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756739636; cv=none; b=akHKKG51Q1MFh88lkDAH1UJ8O9LgfjfFsakNOmk+TmsSzAK3+7+nyJ5rIPWFPD1hRu1RLtUprrhPaPpmQ6kVhk0GVrb745k2OR4sAzbjtTmYHkPMGSAYh/G1EeL5IjRD+rOEWpZ11M80ss4Xj7rJ2y6emj1OwAld3GDMhP18Yz8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756739636; c=relaxed/simple; bh=SHV0Z0u3GPcSt0cRX1hoDRyiVJ2oS372bo4yODFGcWU=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=IMbcW5c/Aq1sv2R/+jxPthAFLVHk/ujw9uzGIF92dGdsuE3koE5MQxFFtSmyThf+781bp8EeMFmm6XhJRag40VxFM5RpFwl1kZkIb2TvSZoSXrqqJWv5VIwT7dtfjnzH5kf5QaxqTowzrfyJ+DxgwucSe+O5kNRdC4SQjd7uQ+Q= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=Y29IaNWE; arc=none smtp.client-ip=170.10.129.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="Y29IaNWE" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1756739633; 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=Y29IaNWEb2HmdS2DE24+xmh9Lk5GDkEr9GsQ/CicHvFodo6FwgH1BxQgKqEr+QHhtsz1hh v4IOe2FV4CFtL0ORMAzL7SZFOvebnYfcORABa+7mwtkLo+sbl9PjLBTF3FB/KocS0QXlS/ oEAVWoy3H3gVgBNYUIvNw4BUPsQ46tg= 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> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.93 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