From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757511Ab1FIMOc (ORCPT ); Thu, 9 Jun 2011 08:14:32 -0400 Received: from hrndva-omtalb.mail.rr.com ([71.74.56.124]:48480 "EHLO hrndva-omtalb.mail.rr.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757284Ab1FIMOb (ORCPT ); Thu, 9 Jun 2011 08:14:31 -0400 X-Authority-Analysis: v=1.1 cv=yMxAJ7W7nAoPh8ZdbvCArpG6pAdHwgpzIvOq8QbMesM= c=1 sm=0 a=vPU38LsHwLEA:10 a=5SG0PmZfjMsA:10 a=Q9fys5e9bTEA:10 a=OPBmh+XkhLl+Enan7BmTLg==:17 a=K6KS5I2C0cWZuo8TJn0A:9 a=PUjeQqilurYA:10 a=OPBmh+XkhLl+Enan7BmTLg==:117 X-Cloudmark-Score: 0 X-Originating-IP: 67.242.120.143 Subject: Re: [PATCH v2] trace: Set __GFP_NORETRY flag for ring buffer allocating process From: Steven Rostedt To: KOSAKI Motohiro Cc: vnagarnaik@google.com, mingo@redhat.com, fweisbec@gmail.com, mrubin@google.com, dhsharp@google.com, linux-kernel@vger.kernel.org In-Reply-To: <4DF0B097.7010805@jp.fujitsu.com> References: <1307490088-8612-1-git-send-email-vnagarnaik@google.com> <1307491302-9236-1-git-send-email-vnagarnaik@google.com> <4DF0B097.7010805@jp.fujitsu.com> Content-Type: text/plain; charset="ISO-8859-15" Date: Thu, 09 Jun 2011 08:14:28 -0400 Message-ID: <1307621668.9218.37.camel@gandalf.stny.rr.com> Mime-Version: 1.0 X-Mailer: Evolution 2.32.2 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 2011-06-09 at 20:37 +0900, KOSAKI Motohiro wrote: > Unfortunately, __GFP_NORETRY is racy and don't work as expected. > If free memory is not enough, the thread may start to reclaim and > another thread can steal the reclaimed memory. And thread0 don't retry. > > Then, thread0's alloc page may fail even though system have enough reclaimable > memory. > > thread0 thread1 > --------------------------------------------------------------- > alloc_pages() > get_page_from_freelist() -> fail > try_to_free_pages() > alloc_pages() > get_page_from_freelist() -> success > get_page_from_freelist() -> fail again > > I think this is mm issue, and afaik, Minchan and some developers are > working on fixing it. but _now_ your patch doesn't work. Have you seen this fail in practice? I'm not too concern if it only triggers when memory is tight. But if it is triggering on normal cases, then that worries me. Thanks, -- Steve