From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx166.postini.com [74.125.245.166]) by kanga.kvack.org (Postfix) with SMTP id 738346B0096 for ; Wed, 17 Apr 2013 10:16:54 -0400 (EDT) Date: Wed, 17 Apr 2013 10:16:39 -0400 From: Naoya Horiguchi Message-ID: <1366208199-50vqp1rm-mutt-n-horiguchi@ah.jp.nec.com> In-Reply-To: <516E446B.5060006@gmail.com> References: <51662D5B.3050001@hitachi.com> <20130411134915.GH16732@two.firstfloor.org> <1365693788-djsd2ymu-mutt-n-horiguchi@ah.jp.nec.com> <516E446B.5060006@gmail.com> Subject: Re: [RFC Patch 0/2] mm: Add parameters to make kernel behavior at memory error on dirty cache selectable Mime-Version: 1.0 Content-Type: text/plain; charset=iso-2022-jp Content-Transfer-Encoding: 7bit Content-Disposition: inline Sender: owner-linux-mm@kvack.org List-ID: To: Simon Jeons Cc: Andi Kleen , Mitsuhiro Tanino , linux-kernel , linux-mm On Wed, Apr 17, 2013 at 02:42:51PM +0800, Simon Jeons wrote: > Hi Naoya, > On 04/11/2013 11:23 PM, Naoya Horiguchi wrote: > > On Thu, Apr 11, 2013 at 03:49:16PM +0200, Andi Kleen wrote: > >>> As a result, if the dirty cache includes user data, the data is lost, > >>> and data corruption occurs if an application uses old data. > >> The application cannot use old data, the kernel code kills it if it > >> would do that. And if it's IO data there is an EIO triggered. > >> > >> iirc the only concern in the past was that the application may miss > >> the asynchronous EIO because it's cleared on any fd access. > >> > >> This is a general problem not specific to memory error handling, > >> as these asynchronous IO errors can happen due to other reason > >> (bad disk etc.) > >> > >> If you're really concerned about this case I think the solution > >> is to make the EIO more sticky so that there is a higher chance > >> than it gets returned. This will make your data much more safe, > >> as it will cover all kinds of IO errors, not just the obscure memory > >> errors. > > I'm interested in this topic, and in previous discussion, what I was said > > is that we can't expect user applications to change their behaviors when > > they get EIO, so globally changing EIO's stickiness is not a great approach. > > The user applications will get EIO firstly or get SIG_KILL firstly? That depends on how the process accesses to the error page, so I can't say which one comes first. Thanks, Naoya Horiguchi -- 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