From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wr0-f197.google.com (mail-wr0-f197.google.com [209.85.128.197]) by kanga.kvack.org (Postfix) with ESMTP id 8DB3B6B05CD for ; Mon, 31 Jul 2017 03:43:54 -0400 (EDT) Received: by mail-wr0-f197.google.com with SMTP id v31so45604291wrc.7 for ; Mon, 31 Jul 2017 00:43:54 -0700 (PDT) Received: from mx1.suse.de (mx2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id e29si25556238wrc.308.2017.07.31.00.43.53 for (version=TLS1 cipher=AES128-SHA bits=128/128); Mon, 31 Jul 2017 00:43:53 -0700 (PDT) Date: Mon, 31 Jul 2017 09:43:50 +0200 From: Michal Hocko Subject: Re: [PATCH] mm: don't zero ballooned pages Message-ID: <20170731074350.GC15767@dhcp22.suse.cz> References: <1501474413-21580-1-git-send-email-wei.w.wang@intel.com> <20170731065508.GE13036@dhcp22.suse.cz> <597EDF3D.8020101@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <597EDF3D.8020101@intel.com> Sender: owner-linux-mm@kvack.org List-ID: To: Wei Wang Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, virtualization@lists.linux-foundation.org, mst@redhat.com, mawilcox@microsoft.com, dave.hansen@intel.com, akpm@linux-foundation.org, zhenwei.pi@youruncloud.com On Mon 31-07-17 15:41:49, Wei Wang wrote: > On 07/31/2017 02:55 PM, Michal Hocko wrote: > >On Mon 31-07-17 12:13:33, Wei Wang wrote: > >>Ballooned pages will be marked as MADV_DONTNEED by the hypervisor and > >>shouldn't be given to the host ksmd to scan. > >Could you point me where this MADV_DONTNEED is done, please? > > Sure. It's done in the hypervisor when the balloon pages are received. > > Please see line 40 at > https://github.com/qemu/qemu/blob/master/hw/virtio/virtio-balloon.c Thanks. Are all hypervisors which are using this API doing this? bb01b64cfab7 doesn't mention the specify hypervisor nor does it mention any real numbers so I suspect the revert is the right thing to do but the changelog should mention all those details. -- Michal Hocko SUSE Labs -- 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