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=-5.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham 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 F2AFDC433E0 for ; Thu, 25 Jun 2020 11:59:24 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id B5E36206C0 for ; Thu, 25 Jun 2020 11:59:24 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B5E36206C0 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 364E96B002F; Thu, 25 Jun 2020 07:59:24 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 314D96B0031; Thu, 25 Jun 2020 07:59:24 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 22A166B0032; Thu, 25 Jun 2020 07:59:24 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0138.hostedemail.com [216.40.44.138]) by kanga.kvack.org (Postfix) with ESMTP id 0978C6B002F for ; Thu, 25 Jun 2020 07:59:24 -0400 (EDT) Received: from smtpin16.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id A3CE11EE6 for ; Thu, 25 Jun 2020 11:59:23 +0000 (UTC) X-FDA: 76967589006.16.tax21_44074c226e4c Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin16.hostedemail.com (Postfix) with ESMTP id 701FB100E690C for ; Thu, 25 Jun 2020 11:59:23 +0000 (UTC) X-HE-Tag: tax21_44074c226e4c X-Filterd-Recvd-Size: 3409 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by imf22.hostedemail.com (Postfix) with ESMTP for ; Thu, 25 Jun 2020 11:59:22 +0000 (UTC) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 25CF71FB; Thu, 25 Jun 2020 04:59:22 -0700 (PDT) Received: from gaia (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 7BA443F73C; Thu, 25 Jun 2020 04:59:20 -0700 (PDT) Date: Thu, 25 Jun 2020 12:59:10 +0100 From: Catalin Marinas To: Steven Price 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 , Andrew Morton Subject: Re: [PATCH v5 22/25] arm64: mte: Enable swap of tagged pages Message-ID: <20200625115909.GA14812@gaia> References: <20200624175244.25837-1-catalin.marinas@arm.com> <20200624175244.25837-23-catalin.marinas@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) X-Rspamd-Queue-Id: 701FB100E690C X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam01 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 Thu, Jun 25, 2020 at 12:37:40PM +0100, Steven Price wrote: > On 24/06/2020 18:52, Catalin Marinas wrote: > > diff --git a/arch/arm64/kernel/mte.c b/arch/arm64/kernel/mte.c > > index 3e08aea56e7a..1712c504df15 100644 > > --- a/arch/arm64/kernel/mte.c > > +++ b/arch/arm64/kernel/mte.c > > @@ -10,6 +10,8 @@ > > #include > > #include > > #include > > +#include > > +#include > > #include > > #include > > @@ -18,15 +20,30 @@ > > #include > > #include > > +static void mte_sync_page_tags(struct page *page, pte_t *ptep, bool check_swap) > > +{ > > + pte_t old_pte = READ_ONCE(*ptep); > > + > > + if (check_swap && is_swap_pte(old_pte)) { > > + swp_entry_t entry = pte_to_swp_entry(old_pte); > > + > > + if (!non_swap_entry(entry) && mte_restore_tags(entry, page)) > > + return; > > + } > > + > > + mte_clear_page_tags(page_address(page)); > > +} > > + > > void mte_sync_tags(pte_t *ptep, pte_t pte) > > { > > struct page *page = pte_page(pte); > > long i, nr_pages = compound_nr(page); > > + bool check_swap = nr_pages == 0; > > /* if PG_mte_tagged is set, tags have already been initialised */ > > for (i = 0; i < nr_pages; i++, page++) { > > This is broken - for check_swap to be true, nr_pages==0, which means we > never enter the loop and nothing happens... > > Except I don't believe compound_nr() will return 0 - it's defined as: > > static inline unsigned long compound_nr(struct page *page) > { > return 1UL << compound_order(page); > } > > Changing it to nr_pages==1 works for me. Ah, I had it as compound_order() and changes to compound_nr() but left the 0 check. Fixed locally. Thanks. -- Catalin