From patchwork Wed Mar 6 10:41:37 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Peter Xu X-Patchwork-Id: 13583889 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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (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 14C36C54E41 for ; Wed, 6 Mar 2024 10:42:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Message-ID:Date:Subject:Cc:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=5GduW20nN8tR/Jd29+M1jT0fjRm9jNp86916HfVpnvM=; b=QfiUcFUjraJ5rz jOFA7G9WR1c7jDx8+IiH7xIxqRw4rWmYGVpfN5MWvBr/kcWf43GGZwJKpqca8FzrzPiI9+nwKRVYJ gIFMUBVxClNAerIQMaAofJRimf00IolhVJ1UglaAOIvwCugAivVLwoe7CJdi8+P3mEeSbwlPmyE9I /nJHdEl2Zk37Q+EyIvF/W4yMPPDf7LJi8D4wWGR479Kzk2TsxavW55Bb8+QkP80/OjeiyhfwrzSkE zJMGb2nlafuYW+1JNEnhXNeXaqrH38IlNgXaJ29HUHOOewRDPONJ9dQ0BIUG6Uv0FEUtPzosaXZkj 2OEOCb1B9H8gEARjiMPg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.97.1 #2 (Red Hat Linux)) id 1rhojG-0000000HSw3-2frv; Wed, 06 Mar 2024 10:42:30 +0000 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by bombadil.infradead.org with esmtps (Exim 4.97.1 #2 (Red Hat Linux)) id 1rhojA-0000000HSr2-2Ow4 for linux-arm-kernel@lists.infradead.org; Wed, 06 Mar 2024 10:42:28 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1709721743; 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=1JTq1zOoPcvZLzyDHIG6xTSG66u1JMVbpFEt5kpx07M=; b=dRQqzD2HhPrpkE4Dw9+lc2GJB/qh5YNbc8ooWioSjk6FPd9SKlQW/VxT94mt73ZsdooNHm n5HyZnpqixkLYnpXutG+jHSwf7nND91xB9GljEnlCRRuQa208ddzADQ6UdYRM+4Wmf7Mdw 9snBfwHhkoxVEJrTkHzIGfGUJOiOTyU= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-630-w92BStQdNuqU_EljwB5_jw-1; Wed, 06 Mar 2024 05:42:18 -0500 X-MC-Unique: w92BStQdNuqU_EljwB5_jw-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.rdu2.redhat.com [10.11.54.3]) (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 mimecast-mx02.redhat.com (Postfix) with ESMTPS id 6AC0E800267; Wed, 6 Mar 2024 10:42:17 +0000 (UTC) Received: from x1n.redhat.com (unknown [10.72.116.8]) by smtp.corp.redhat.com (Postfix) with ESMTP id A7360111E3F3; Wed, 6 Mar 2024 10:42:11 +0000 (UTC) From: peterx@redhat.com To: linux-mm@kvack.org, linux-kernel@vger.kernel.org Cc: linuxppc-dev@lists.ozlabs.org, Andrew Morton , Muchun Song , Jason Gunthorpe , peterx@redhat.com, Matthew Wilcox , Mike Rapoport , Christophe Leroy , x86@kernel.org, sparclinux@vger.kernel.org, linux-arm-kernel@lists.infradead.org Subject: [PATCH RFC 03/13] mm/gup: Check p4d presence before going on Date: Wed, 6 Mar 2024 18:41:37 +0800 Message-ID: <20240306104147.193052-4-peterx@redhat.com> In-Reply-To: <20240306104147.193052-1-peterx@redhat.com> References: <20240306104147.193052-1-peterx@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.3 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240306_024224_834161_A9042A1B X-CRM114-Status: GOOD ( 11.61 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org From: Peter Xu Currently there should have no p4d swap entries so it may not matter much, however this may help us to rule out swap entries in pXd_huge() API, which will include p4d_huge(). The p4d_present() checks make it 100% clear that we won't rely on p4d_huge() for swap entries. Signed-off-by: Peter Xu --- mm/gup.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/mm/gup.c b/mm/gup.c index 69a777f4fc5c..f87a7d90f2ae 100644 --- a/mm/gup.c +++ b/mm/gup.c @@ -776,7 +776,7 @@ static struct page *follow_p4d_mask(struct vm_area_struct *vma, p4dp = p4d_offset(pgdp, address); p4d = READ_ONCE(*p4dp); - if (p4d_none(p4d)) + if (p4d_none(p4d) || !p4d_present(p4d)) return no_page_table(vma, flags); BUILD_BUG_ON(p4d_huge(p4d)); if (unlikely(p4d_bad(p4d))) @@ -3069,7 +3069,7 @@ static int gup_p4d_range(pgd_t *pgdp, pgd_t pgd, unsigned long addr, unsigned lo p4d_t p4d = READ_ONCE(*p4dp); next = p4d_addr_end(addr, end); - if (p4d_none(p4d)) + if (p4d_none(p4d) || !p4d_present(p4d)) return 0; BUILD_BUG_ON(p4d_huge(p4d)); if (unlikely(is_hugepd(__hugepd(p4d_val(p4d))))) {