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 717E66B01F9 for ; Tue, 30 Mar 2010 02:40:03 -0400 (EDT) Received: from m4.gw.fujitsu.co.jp ([10.0.50.74]) by fgwmail7.fujitsu.co.jp (Fujitsu Gateway) with ESMTP id o2U6eEwk008566 for (envelope-from kosaki.motohiro@jp.fujitsu.com); Tue, 30 Mar 2010 15:40:14 +0900 Received: from smail (m4 [127.0.0.1]) by outgoing.m4.gw.fujitsu.co.jp (Postfix) with ESMTP id 278E545DE60 for ; Tue, 30 Mar 2010 15:40:13 +0900 (JST) Received: from s4.gw.fujitsu.co.jp (s4.gw.fujitsu.co.jp [10.0.50.94]) by m4.gw.fujitsu.co.jp (Postfix) with ESMTP id 9C1D445DE70 for ; Tue, 30 Mar 2010 15:40:12 +0900 (JST) Received: from s4.gw.fujitsu.co.jp (localhost.localdomain [127.0.0.1]) by s4.gw.fujitsu.co.jp (Postfix) with ESMTP id E76C81DB804C for ; Tue, 30 Mar 2010 15:40:11 +0900 (JST) Received: from m106.s.css.fujitsu.com (m106.s.css.fujitsu.com [10.249.87.106]) by s4.gw.fujitsu.co.jp (Postfix) with ESMTP id 4770CE18003 for ; Tue, 30 Mar 2010 15:40:08 +0900 (JST) From: KOSAKI Motohiro Subject: Re: [PATCH]vmscan: handle underflow for get_scan_ratio 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 Date: Tue, 30 Mar 2010 15:40:07 +0900 (JST) Sender: owner-linux-mm@kvack.org To: Shaohua Li Cc: kosaki.motohiro@jp.fujitsu.com, "linux-mm@kvack.org" , "linux-kernel@vger.kernel.org" , "akpm@linux-foundation.org" , "Wu, Fengguang" List-ID: > 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. -- 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