From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx203.postini.com [74.125.245.203]) by kanga.kvack.org (Postfix) with SMTP id 747C56B0044 for ; Tue, 1 May 2012 14:15:18 -0400 (EDT) Received: by yenm8 with SMTP id m8so2944673yen.14 for ; Tue, 01 May 2012 11:15:17 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: <4FA02603.80807@openvz.org> References: <20120430112903.14137.81692.stgit@zurg> <20120430112910.14137.28935.stgit@zurg> <4FA02603.80807@openvz.org> From: KOSAKI Motohiro Date: Tue, 1 May 2012 14:14:57 -0400 Message-ID: Subject: Re: [PATCH RFC 3/3] proc/smaps: show amount of hwpoison pages Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Sender: owner-linux-mm@kvack.org List-ID: To: Konstantin Khlebnikov Cc: "linux-mm@kvack.org" , "linux-kernel@vger.kernel.org" , Andrew Morton , Andi Kleen On Tue, May 1, 2012 at 2:05 PM, Konstantin Khlebnikov wrote: > KOSAKI Motohiro wrote: >> >> On Mon, Apr 30, 2012 at 7:29 AM, Konstantin Khlebnikov >> =A0wrote: >>> >>> This patch adds line "HWPoinson: =A0kB" into /proc/pid/smaps if >>> CONFIG_MEMORY_FAILURE=3Dy and some HWPoison pages were found. >>> This may be useful for searching applications which use a broken memory= . >> >> >> I dislike "maybe useful" claim. If we don't know exact motivation of a >> feature, >> we can't maintain them especially when a bugfix can't avoid ABI change. >> >> Please write down exact use case. > > I don't know how to exactly use this hw-poison stuff, but smaps suppose t= o > export state of ptes in vma. It seems to rational to show also hw-poisone= d > ptes, > since kernel has this feature and pte can be in hw-poisoned state. > > and now everyone can easily find them: > # sudo grep HWPoison /proc/*/smaps First, I don't think "we can expose it" is good reason. Second, hw-poisoned= mean such process is going to be killed at next page touch. But I can't imagine anyone can use its information because it's racy against process kill. I think admin should use mce log. So, until we find a good use case, I don't ack this. -- 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/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org