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=-2.5 required=3.0 tests=MAILING_LIST_MULTI,SPF_PASS, URIBL_BLOCKED,USER_AGENT_MUTT 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 43340C4321D for ; Mon, 20 Aug 2018 14:26:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 01E0A21581 for ; Mon, 20 Aug 2018 14:26:40 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 01E0A21581 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726778AbeHTRm3 (ORCPT ); Mon, 20 Aug 2018 13:42:29 -0400 Received: from mx2.suse.de ([195.135.220.15]:47822 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726021AbeHTRm3 (ORCPT ); Mon, 20 Aug 2018 13:42:29 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay1.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id AE5D6AE4D; Mon, 20 Aug 2018 14:26:36 +0000 (UTC) Date: Mon, 20 Aug 2018 16:26:36 +0200 From: Michal Hocko To: Andi Kleen Cc: Vlastimil Babka , Thomas Gleixner , Ingo Molnar , "H . Peter Anvin" , x86@kernel.org, linux-kernel@vger.kernel.org, Linus Torvalds , Dave Hansen , stable@vger.kernel.org, Adrian Schroeter , Dominique Leuenberger Subject: Re: [PATCH] x86/speculation/l1tf: fix overflow on l1tf_pfn_limit() on 32bit Message-ID: <20180820142636.GM29735@dhcp22.suse.cz> References: <20180820095835.5298-1-vbabka@suse.cz> <20180820142027.GL12066@tassilo.jf.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180820142027.GL12066@tassilo.jf.intel.com> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon 20-08-18 07:20:27, Andi Kleen wrote: > On Mon, Aug 20, 2018 at 11:58:35AM +0200, Vlastimil Babka wrote: > > On 32bit PAE kernels on 64bit hardware with enough physical bits, > > l1tf_pfn_limit() will overflow unsigned long. This in turn affects > > max_swapfile_size() and can lead to swapon returning -EINVAL. This has been > > observed in a 32bit guest with 42 bits physical address size, where > > max_swapfile_size() overflows exactly to 1 << 32, thus zero, and produces the > > following warning to dmesg: > > > > [ 6.396845] Truncating oversized swap area, only using 0k out of 2047996k > > > > Fix this by using unsigned long long instead. > > Looks good. > > Acked-by: Andi Kleen > > BTW our much worse problems right now are crash reports on several > stable kernels, especially with large pages Do you have any reference? > I'll dig into this more today, but if you have any hints from testing/fixing > your own backports please share them. Well, we have seen some issues on pre 3.12 kernels due to misbackporting prot_none mitigations. PMD format is different in pre 4.4 kernels. Maybe this is a similar issue. -- Michal Hocko SUSE Labs