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 X-Spam-Level: X-Spam-Status: No, score=-1.0 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id A9537C433E0 for ; Wed, 24 Jun 2020 18:33:11 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 66D8D20767 for ; Wed, 24 Jun 2020 18:33:11 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="bh9ABLGa" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 66D8D20767 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linux-foundation.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id D2B976B002A; Wed, 24 Jun 2020 14:33:10 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id CD9CF6B002B; Wed, 24 Jun 2020 14:33:10 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id BCA406B002D; Wed, 24 Jun 2020 14:33:10 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0243.hostedemail.com [216.40.44.243]) by kanga.kvack.org (Postfix) with ESMTP id A48526B002A for ; Wed, 24 Jun 2020 14:33:10 -0400 (EDT) Received: from smtpin08.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id 547072C7C for ; Wed, 24 Jun 2020 18:33:10 +0000 (UTC) X-FDA: 76964952540.08.birth22_5b03e1626e46 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin08.hostedemail.com (Postfix) with ESMTP id 1E11E1819E766 for ; Wed, 24 Jun 2020 18:33:10 +0000 (UTC) X-HE-Tag: birth22_5b03e1626e46 X-Filterd-Recvd-Size: 2832 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf09.hostedemail.com (Postfix) with ESMTP for ; Wed, 24 Jun 2020 18:33:09 +0000 (UTC) Received: from X1 (nat-ab2241.sltdut.senawave.net [162.218.216.4]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 7598820738; Wed, 24 Jun 2020 18:33:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1593023588; bh=EiMO72eDpdKXWS6Tvej3pkFu8M9hxYW+MQgO4jUfBbM=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=bh9ABLGaUhujAR3M9Ke47tCxbYeH0Sw4aC0Ka1fMN2nxyRMo37M8av85ngm12i5Iu Wfzzo1P5nkIMiYT/9bB0qPGr0iWcm613AtvRkpTfzmb86A4FH1YS+OpAkc/kCaGM1D SJVGiQua+41yZ2bcbdsvS3XS7Xq91WPbUIUN1k8w= Date: Wed, 24 Jun 2020 11:33:07 -0700 From: Andrew Morton To: Catalin Marinas Cc: linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org, linux-arch@vger.kernel.org, Will Deacon , Dave P Martin , Vincenzo Frascino , Szabolcs Nagy , Kevin Brodsky , Andrey Konovalov , Peter Collingbourne , Steven Price Subject: Re: [PATCH v5 06/25] mm: Add PG_ARCH_2 page flag Message-Id: <20200624113307.6165b3db2404c9d37b870a90@linux-foundation.org> In-Reply-To: <20200624175244.25837-7-catalin.marinas@arm.com> References: <20200624175244.25837-1-catalin.marinas@arm.com> <20200624175244.25837-7-catalin.marinas@arm.com> X-Mailer: Sylpheed 3.5.1 (GTK+ 2.24.32; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: 1E11E1819E766 X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam03 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Wed, 24 Jun 2020 18:52:25 +0100 Catalin Marinas wrote: > From: Steven Price > > For arm64 MTE support it is necessary to be able to mark pages that > contain user space visible tags that will need to be saved/restored e.g. > when swapped out. > > To support this add a new arch specific flag (PG_ARCH_2) that arch code > can opt into using ARCH_USES_PG_ARCH_2. > > ... > > --- a/fs/proc/page.c > +++ b/fs/proc/page.c > @@ -217,6 +217,9 @@ u64 stable_page_flags(struct page *page) > u |= kpf_copy_bit(k, KPF_PRIVATE_2, PG_private_2); > u |= kpf_copy_bit(k, KPF_OWNER_PRIVATE, PG_owner_priv_1); > u |= kpf_copy_bit(k, KPF_ARCH, PG_arch_1); > +#ifdef CONFIG_ARCH_USES_PG_ARCH_2 > + u |= kpf_copy_bit(k, KPF_ARCH_2, PG_arch_2); > +#endif Do we need CONFIG_ARCH_USES_PG_ARCH_2? What would be the downside to giving every architecture a PG_arch_2, but only arm64 uses it (at present)?