From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755566Ab0C3GI5 (ORCPT ); Tue, 30 Mar 2010 02:08:57 -0400 Received: from fgwmail7.fujitsu.co.jp ([192.51.44.37]:52527 "EHLO fgwmail7.fujitsu.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754649Ab0C3GI4 (ORCPT ); Tue, 30 Mar 2010 02:08:56 -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, fengguang.wu@intel.com In-Reply-To: <20100330055304.GA2983@sli10-desk.sh.intel.com> References: <20100330055304.GA2983@sli10-desk.sh.intel.com> Message-Id: <20100330150453.8E9F.A69D9226@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit X-Mailer: Becky! ver. 2.50.07 [ja] Date: Tue, 30 Mar 2010 15:08:53 +0900 (JST) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 and reproduce program? I'll digg it. Very unfortunately, this patch isn't acceptable. In past time, vmscan had similar logic, but 1% swap-out made lots bug reports.