From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755766Ab0C3GkQ (ORCPT ); Tue, 30 Mar 2010 02:40:16 -0400 Received: from fgwmail5.fujitsu.co.jp ([192.51.44.35]:44386 "EHLO fgwmail5.fujitsu.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755692Ab0C3GkO (ORCPT ); Tue, 30 Mar 2010 02:40:14 -0400 X-SecurityPolicyCheck-FJ: OK by FujitsuOutboundMailChecker v1.3.1 From: KOSAKI Motohiro To: Shaohua Li Subject: Re: [PATCH]vmscan: handle underflow for get_scan_ratio Cc: kosaki.motohiro@jp.fujitsu.com, "linux-mm@kvack.org" , "linux-kernel@vger.kernel.org" , "akpm@linux-foundation.org" , "Wu, Fengguang" In-Reply-To: <1269930756.17240.4.camel@sli10-desk.sh.intel.com> References: <20100330150453.8E9F.A69D9226@jp.fujitsu.com> <1269930756.17240.4.camel@sli10-desk.sh.intel.com> Message-Id: <20100330153750.8EA2.A69D9226@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8bit X-Mailer: Becky! ver. 2.50.07 [ja] Date: Tue, 30 Mar 2010 15:40:07 +0900 (JST) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > On Tue, 2010-03-30 at 14:08 +0800, KOSAKI Motohiro wrote: > > Hi > > > > > Commit 84b18490d1f1bc7ed5095c929f78bc002eb70f26 introduces a regression. > > > With it, our tmpfs test always oom. The test has a lot of rotated anon > > > pages and cause percent[0] zero. Actually the percent[0] is a very small > > > value, but our calculation round it to zero. The commit makes vmscan > > > completely skip anon pages and cause oops. > > > An option is if percent[x] is zero in get_scan_ratio(), forces it > > > to 1. See below patch. > > > But the offending commit still changes behavior. Without the commit, we scan > > > all pages if priority is zero, below patch doesn't fix this. Don't know if > > > It's required to fix this too. > > > > Can you please post your /proc/meminfo > attached. > > and reproduce program? I'll digg it. > our test is quite sample. mount tmpfs with double memory size and store several > copies (memory size * 2/G) of kernel in tmpfs, and then do kernel build. > for example, there is 3G memory and then tmpfs size is 6G and there is 6 > kernel copy. Wow, tmpfs size > memsize! > > Very unfortunately, this patch isn't acceptable. In past time, vmscan > > had similar logic, but 1% swap-out made lots bug reports. > can you elaborate this? > Completely restore previous behavior (do full scan with priority 0) is > ok too. This is a option. but we need to know the root cause anyway. if not, we might reintroduce this issue again in the future.