From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751753AbaCFXMK (ORCPT ); Thu, 6 Mar 2014 18:12:10 -0500 Received: from mail.linuxfoundation.org ([140.211.169.12]:36448 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751190AbaCFXMJ (ORCPT ); Thu, 6 Mar 2014 18:12:09 -0500 Date: Thu, 6 Mar 2014 15:12:06 -0800 From: Andrew Morton To: Johannes Weiner Cc: stable@kernel.org, riel@redhat.com, mgorman@suse.de, jstancek@redhat.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [merged] mm-page_alloc-reset-aging-cycle-with-gfp_thisnode-v2.patch removed from -mm tree Message-Id: <20140306151206.6228ae8933af538048aa056c@linux-foundation.org> In-Reply-To: <20140306230404.GY6963@cmpxchg.org> References: <5318dca5.AwhU/92X21JgbpdE%akpm@linux-foundation.org> <20140306214927.GB11171@cmpxchg.org> <20140306135635.6999d703429afb7fd3949304@linux-foundation.org> <20140306230404.GY6963@cmpxchg.org> X-Mailer: Sylpheed 3.2.0beta5 (GTK+ 2.24.10; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 6 Mar 2014 18:04:04 -0500 Johannes Weiner wrote: > > what bug does it fix and what are the user-visible effects?? > > Ok, maybe this is better? > > --- > > GFP_THISNODE is for callers that implement their own clever fallback > to remote nodes. It restricts the allocation to the specified node > and does not invoke reclaim, assuming that the caller will take care > of it when the fallback fails, e.g. through a subsequent allocation > request without GFP_THISNODE set. > > However, many current GFP_THISNODE users only want the node exclusive > aspect of the flag, without actually implementing their own fallback > or triggering reclaim if necessary. This results in things like page > migration failing prematurely even when there is easily reclaimable > memory available, unless kswapd happens to be running already or a > concurrent allocation attempt triggers the necessary reclaim. > > Convert all callsites that don't implement their own fallback strategy > to __GFP_THISNODE. This restricts the allocation a single node too, > but at the same time allows the allocator to enter the slowpath, wake > kswapd, and invoke direct reclaim if necessary, to make the allocation > happen when memory is full. Looks good, thanks. I'll send this Linuswards next week.