From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail202.messagelabs.com (mail202.messagelabs.com [216.82.254.227]) by kanga.kvack.org (Postfix) with SMTP id E67686B0047 for ; Sun, 26 Sep 2010 22:17:37 -0400 (EDT) Received: from m6.gw.fujitsu.co.jp ([10.0.50.76]) by fgwmail6.fujitsu.co.jp (Fujitsu Gateway) with ESMTP id o8R2HNwc016913 for (envelope-from kosaki.motohiro@jp.fujitsu.com); Mon, 27 Sep 2010 11:17:23 +0900 Received: from smail (m6 [127.0.0.1]) by outgoing.m6.gw.fujitsu.co.jp (Postfix) with ESMTP id A341745DE4E for ; Mon, 27 Sep 2010 11:17:23 +0900 (JST) Received: from s6.gw.fujitsu.co.jp (s6.gw.fujitsu.co.jp [10.0.50.96]) by m6.gw.fujitsu.co.jp (Postfix) with ESMTP id 872B545DE4C for ; Mon, 27 Sep 2010 11:17:23 +0900 (JST) Received: from s6.gw.fujitsu.co.jp (localhost.localdomain [127.0.0.1]) by s6.gw.fujitsu.co.jp (Postfix) with ESMTP id 729BCE38001 for ; Mon, 27 Sep 2010 11:17:23 +0900 (JST) Received: from ml13.s.css.fujitsu.com (ml13.s.css.fujitsu.com [10.249.87.103]) by s6.gw.fujitsu.co.jp (Postfix) with ESMTP id 2DDF41DB8013 for ; Mon, 27 Sep 2010 11:17:20 +0900 (JST) From: KOSAKI Motohiro Subject: Re: [PATCH] mm: do not print backtraces on GFP_ATOMIC failures In-Reply-To: <1285088427.2617.723.camel@edumazet-laptop> References: <20100921094638.9910add0.akpm@linux-foundation.org> <1285088427.2617.723.camel@edumazet-laptop> Message-Id: <20100927110723.6B37.A69D9226@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8bit Date: Mon, 27 Sep 2010 11:17:19 +0900 (JST) Sender: owner-linux-mm@kvack.org To: Eric Dumazet Cc: kosaki.motohiro@jp.fujitsu.com, Andrew Morton , Rik van Riel , linux-mm@kvack.org, linux-kernel@vger.kernel.org, netdev@vger.kernel.org List-ID: > > > @@ -72,7 +72,7 @@ struct vm_area_struct; > > > /* This equals 0, but use constants in case they ever change */ > > > #define GFP_NOWAIT (GFP_ATOMIC & ~__GFP_HIGH) > > > /* GFP_ATOMIC means both !wait (__GFP_WAIT not set) and use emergency pool */ > > > -#define GFP_ATOMIC (__GFP_HIGH) > > > +#define GFP_ATOMIC (__GFP_HIGH | __GFP_NOWARN) > > > #define GFP_NOIO (__GFP_WAIT) > > > #define GFP_NOFS (__GFP_WAIT | __GFP_IO) > > > #define GFP_KERNEL (__GFP_WAIT | __GFP_IO | __GFP_FS) > > > > A much finer-tuned implementation would be to add __GFP_NOWARN just to > > the networking call sites. I asked about this in June and it got > > nixed: > > > > http://www.spinics.net/lists/netdev/msg131965.html > > -- > > Yes, I remember this particular report was useful to find and correct a > bug. > > I dont know what to say. > > Being silent or verbose, it really depends on the context ? At least, MM developers don't want to track network allocation failure issue. We don't have enough knowledge in this area. To be honest, We are unhappy current bad S/N bug report rate ;) Traditionally, We hoped this warnings help to debug VM issue. but It haven't happen. We haven't detect VM issue from this allocation failure report. Instead, We've received a lot of network allocation failure report. Recently, The S/N ratio became more bad. If the network device enable jumbo frame feature, order-2 GFP_ATOMIC allocation is called frequently. Anybody don't have to assume order-2 allocation can success anytime. I'm not against accurate warning at all. but I cant tolerate this semi-random warning steal our time. If anyone will not make accurate warning, I hope to remove this one completely instead. -- 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