From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx206.postini.com [74.125.245.206]) by kanga.kvack.org (Postfix) with SMTP id 575936B0037 for ; Thu, 11 Apr 2013 11:23:15 -0400 (EDT) Date: Thu, 11 Apr 2013 11:23:08 -0400 From: Naoya Horiguchi Message-ID: <1365693788-djsd2ymu-mutt-n-horiguchi@ah.jp.nec.com> In-Reply-To: <20130411134915.GH16732@two.firstfloor.org> References: <51662D5B.3050001@hitachi.com> <20130411134915.GH16732@two.firstfloor.org> 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: Andi Kleen Cc: Mitsuhiro Tanino , linux-kernel , linux-mm 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. I'm working on a new pagecache tag based mechanism to solve this. But it needs time and more discussions. So I guess Tanino-san suggests giving up on dirty pagecache errors as a quick solution. Thanks, Naoya -- 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