From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qt0-f197.google.com (mail-qt0-f197.google.com [209.85.216.197]) by kanga.kvack.org (Postfix) with ESMTP id 392016B025F for ; Mon, 7 Aug 2017 05:37:34 -0400 (EDT) Received: by mail-qt0-f197.google.com with SMTP id i19so40718085qte.5 for ; Mon, 07 Aug 2017 02:37:34 -0700 (PDT) Received: from mx1.redhat.com (mx1.redhat.com. [209.132.183.28]) by mx.google.com with ESMTPS id g141si6712928qke.458.2017.08.07.02.37.33 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 07 Aug 2017 02:37:33 -0700 (PDT) Subject: Re: [PATCH RESEND] mm: don't zero ballooned pages References: <1501761557-9758-1-git-send-email-wei.w.wang@intel.com> <9ac31505-0996-2822-752e-8ec055373aa0@redhat.com> <20170807092525.GE32434@dhcp22.suse.cz> From: David Hildenbrand Message-ID: <8b862c93-1a9f-9247-8401-5092cc35a857@redhat.com> Date: Mon, 7 Aug 2017 11:37:26 +0200 MIME-Version: 1.0 In-Reply-To: <20170807092525.GE32434@dhcp22.suse.cz> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Michal Hocko Cc: Wei Wang , linux-kernel@vger.kernel.org, linux-mm@kvack.org, virtualization@lists.linux-foundation.org, mst@redhat.com, zhenwei.pi@youruncloud.com, dave.hansen@intel.com, akpm@linux-foundation.org, mawilcox@microsoft.com, Andrea Arcangeli > Maybe it is my absolute lack of familiarity with what the host actually > does with balloon pages but I fail to see why the above matters at all. > ksm will not try to merge sub page units (4k for hugetlb or a large base > page). And if you need to hide the guest contents then the host can > clear the respective subpage just fine. So could you be more explicit > why MADV_DONTNEED matters at all? Also does any host actually share sub > pages between different guests? This sounds like a bad idea to me in > general. > Okay, I think I got the issue wrong. I thought that the original patch tried to also fix a corner case where the guest would assume that it would get supplied zero pages afterwards. Please ignore the noise. :) -- Thanks, David -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org