From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf0-f197.google.com (mail-pf0-f197.google.com [209.85.192.197]) by kanga.kvack.org (Postfix) with ESMTP id CE9396B0253 for ; Mon, 30 Jan 2017 18:58:37 -0500 (EST) Received: by mail-pf0-f197.google.com with SMTP id d123so224436287pfd.0 for ; Mon, 30 Jan 2017 15:58:37 -0800 (PST) Received: from lgeamrelo12.lge.com (LGEAMRELO12.lge.com. [156.147.23.52]) by mx.google.com with ESMTP id d11si14082972plj.282.2017.01.30.15.58.36 for ; Mon, 30 Jan 2017 15:58:37 -0800 (PST) Date: Tue, 31 Jan 2017 08:58:34 +0900 From: Minchan Kim Subject: Re: [PATCH 2/2] mm: vmpressure: fix sending wrong events on underflow Message-ID: <20170130235834.GC7942@bbox> References: <1485504817-3124-1-git-send-email-vinmenon@codeaurora.org> <1485504817-3124-2-git-send-email-vinmenon@codeaurora.org> MIME-Version: 1.0 In-Reply-To: <1485504817-3124-2-git-send-email-vinmenon@codeaurora.org> Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline Sender: owner-linux-mm@kvack.org List-ID: To: Vinayak Menon Cc: akpm@linux-foundation.org, hannes@cmpxchg.org, mgorman@techsingularity.net, vbabka@suse.cz, mhocko@suse.com, riel@redhat.com, vdavydov.dev@gmail.com, anton.vorontsov@linaro.org, shashim@codeaurora.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org On Fri, Jan 27, 2017 at 01:43:37PM +0530, Vinayak Menon wrote: > At the end of a window period, if the reclaimed pages > is greater than scanned, an unsigned underflow can > result in a huge pressure value and thus a critical event. > Reclaimed pages is found to go higher than scanned because > of the addition of reclaimed slab pages to reclaimed in > shrink_node without a corresponding increment to scanned > pages. Minchan Kim mentioned that this can also happen in > the case of a THP page where the scanned is 1 and reclaimed > could be 512. > > Signed-off-by: Vinayak Menon Acked-by: Minchan Kim Thanks for the fix up! -- 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 From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754606AbdAaAAG (ORCPT ); Mon, 30 Jan 2017 19:00:06 -0500 Received: from LGEAMRELO12.lge.com ([156.147.23.52]:33397 "EHLO lgeamrelo12.lge.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753362AbdAaAAF (ORCPT ); Mon, 30 Jan 2017 19:00:05 -0500 X-Original-SENDERIP: 156.147.1.151 X-Original-MAILFROM: minchan@kernel.org X-Original-SENDERIP: 165.244.249.26 X-Original-MAILFROM: minchan@kernel.org X-Original-SENDERIP: 10.177.223.161 X-Original-MAILFROM: minchan@kernel.org Date: Tue, 31 Jan 2017 08:58:34 +0900 From: Minchan Kim To: Vinayak Menon CC: , , , , , , , , , , Subject: Re: [PATCH 2/2] mm: vmpressure: fix sending wrong events on underflow Message-ID: <20170130235834.GC7942@bbox> References: <1485504817-3124-1-git-send-email-vinmenon@codeaurora.org> <1485504817-3124-2-git-send-email-vinmenon@codeaurora.org> MIME-Version: 1.0 In-Reply-To: <1485504817-3124-2-git-send-email-vinmenon@codeaurora.org> User-Agent: Mutt/1.5.24 (2015-08-30) X-MIMETrack: Itemize by SMTP Server on LGEKRMHUB02/LGE/LG Group(Release 8.5.3FP6|November 21, 2013) at 2017/01/31 08:58:35, Serialize by Router on LGEKRMHUB02/LGE/LG Group(Release 8.5.3FP6|November 21, 2013) at 2017/01/31 08:58:35, Serialize complete at 2017/01/31 08:58:35 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Jan 27, 2017 at 01:43:37PM +0530, Vinayak Menon wrote: > At the end of a window period, if the reclaimed pages > is greater than scanned, an unsigned underflow can > result in a huge pressure value and thus a critical event. > Reclaimed pages is found to go higher than scanned because > of the addition of reclaimed slab pages to reclaimed in > shrink_node without a corresponding increment to scanned > pages. Minchan Kim mentioned that this can also happen in > the case of a THP page where the scanned is 1 and reclaimed > could be 512. > > Signed-off-by: Vinayak Menon Acked-by: Minchan Kim Thanks for the fix up!