From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753661AbaBYUg6 (ORCPT ); Tue, 25 Feb 2014 15:36:58 -0500 Received: from mx1.redhat.com ([209.132.183.28]:60268 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752635AbaBYUg4 (ORCPT ); Tue, 25 Feb 2014 15:36:56 -0500 Message-ID: <530CFEDF.3060801@redhat.com> Date: Tue, 25 Feb 2014 15:36:47 -0500 From: Rik van Riel User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.2.0 MIME-Version: 1.0 To: Johannes Weiner , Andrew Morton CC: Jan Stancek , Mel Gorman , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [patch 1/2] mm: page_alloc: reset aging cycle with GFP_THISNODE References: <1393360022-22566-1-git-send-email-hannes@cmpxchg.org> In-Reply-To: <1393360022-22566-1-git-send-email-hannes@cmpxchg.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 02/25/2014 03:27 PM, Johannes Weiner wrote: > Jan Stancek reports manual page migration encountering allocation > failures after some pages when there is still plenty of memory free, > and bisected the problem down to 81c0a2bb515f ("mm: page_alloc: fair > zone allocator policy"). > > The problem is that page migration uses GFP_THISNODE and this makes > the page allocator bail out before entering the slowpath entirely, > without resetting the zone round-robin batches. A string of such > allocations will fail long before the node's free memory is exhausted. > > GFP_THISNODE is a special flag for callsites that implement their own > clever node fallback and so no direct reclaim should be invoked. But > if the allocations fail, the fair allocation batches should still be > reset, and if the node is full, it should be aged in the background. > > Make GFP_THISNODE wake up kswapd and reset the zone batches, but bail > out before entering direct reclaim to not stall the allocating task. > > Reported-by: Jan Stancek > Signed-off-by: Johannes Weiner > Cc: # 3.12+ Acked-by: Rik van Riel -- All rights reversed