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=-8.5 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=unavailable 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 4CB71C433E0 for ; Thu, 25 Jun 2020 11:39:46 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 1894D2088E for ; Thu, 25 Jun 2020 11:39:46 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="vImuHAlp" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 1894D2088E Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=merlin.20170209; h=Sender:Content-Type: Content-Transfer-Encoding:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:Date:Message-ID:From: References:To:Subject:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=1HqYD86Lth1oiZbFDQf/LXMzbu/Wl5l7Rzf/L4jV/2s=; b=vImuHAlpkFOW45bxob9JMLtOu btLAfEDvQvTDiusLq1rQHqzlgobF3mVhX1PdI7i/yMZySTkJcvz/EQ/nqmOSWTEa1f78HYUTcRByA 9JmYWNAne8iXK24+sJcFWoMEXu+bd1rejTBQRYFn0MYrl3VayJmbcWdEuj7WzClTQWOfsfL/+Ptc0 Z+HW3ijwNfMrvg+FUqkYd9XPkRIij70ofHq9wffjixNszVDSsrUtIt5hkOg0Zk5GNpxRMDUuXI/mx QReVMOhnlyneIgY5+e7rPhabHRAoZ+QSlkepBCv997fkJd3TSdch2/katzxYeyEf0TeLfFaXiQosj qzlT8nD6Q==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1joQCf-0003Jw-Bi; Thu, 25 Jun 2020 11:38:01 +0000 Received: from foss.arm.com ([217.140.110.172]) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1joQCc-0003Ik-Nd for linux-arm-kernel@lists.infradead.org; Thu, 25 Jun 2020 11:37:59 +0000 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 518051FB; Thu, 25 Jun 2020 04:37:57 -0700 (PDT) Received: from [192.168.1.179] (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id B3B933F73C; Thu, 25 Jun 2020 04:37:55 -0700 (PDT) Subject: Re: [PATCH v5 22/25] arm64: mte: Enable swap of tagged pages To: Catalin Marinas , linux-arm-kernel@lists.infradead.org References: <20200624175244.25837-1-catalin.marinas@arm.com> <20200624175244.25837-23-catalin.marinas@arm.com> From: Steven Price Message-ID: Date: Thu, 25 Jun 2020 12:37:40 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.8.0 MIME-Version: 1.0 In-Reply-To: <20200624175244.25837-23-catalin.marinas@arm.com> Content-Language: en-GB X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-arch@vger.kernel.org, Szabolcs Nagy , Andrey Konovalov , Kevin Brodsky , Peter Collingbourne , linux-mm@kvack.org, Andrew Morton , Vincenzo Frascino , Will Deacon , Dave P Martin Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 24/06/2020 18:52, Catalin Marinas wrote: > From: Steven Price > > When swapping pages out to disk it is necessary to save any tags that > have been set, and restore when swapping back in. Make use of the new > page flag (PG_ARCH_2, locally named PG_mte_tagged) to identify pages > with tags. When swapping out these pages the tags are stored in memory > and later restored when the pages are brought back in. Because shmem can > swap pages back in without restoring the userspace PTE it is also > necessary to add a hook for shmem. > > Signed-off-by: Steven Price > [catalin.marinas@arm.com: move function prototypes to mte.h] > [catalin.marinas@arm.com: drop '_tags' from arch_swap_restore_tags()] > Signed-off-by: Catalin Marinas > Cc: Andrew Morton > Cc: Will Deacon > --- > > Notes: > New in v4. > [...] > 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. Steve _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel