Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932411AbZJ0VMl (ORCPT ); Tue, 27 Oct 2009 17:12:41 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932391AbZJ0VMl (ORCPT ); Tue, 27 Oct 2009 17:12:41 -0400 Received: from smtp-out.google.com ([216.239.33.17]:14331 "EHLO smtp-out.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932265AbZJ0VMk (ORCPT ); Tue, 27 Oct 2009 17:12:40 -0400 DomainKey-Signature: a=rsa-sha1; s=beta; d=google.com; c=nofws; q=dns; h=date:from:x-x-sender:to:cc:subject:in-reply-to:message-id: references:user-agent:mime-version:content-type:x-system-of-record; b=P+V3h/hL8Lxe9BGMVU2E3yn8NHaZywdLIfPfG3oKWYV4fYPSKtUGoi9rm56XU5dQo WjSHCnuQPFn951HBkcIFg== Date: Tue, 27 Oct 2009 14:12:36 -0700 (PDT) From: David Rientjes X-X-Sender: rientjes@chino.kir.corp.google.com To: Andrew Morton cc: Mel Gorman , stable@kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Frans Pop , Jiri Kosina , Sven Geggus , Karol Lewandowski , Tobias Oetiker , KOSAKI Motohiro , Pekka Enberg , Rik van Riel , Christoph Lameter , Stephan von Krawczynski , kernel-testers@vger.kernel.org, Mel Gorman Subject: Re: [PATCH 2/3] page allocator: Do not allow interrupts to use ALLOC_HARDER In-Reply-To: <20091027130924.fa903f5a.akpm@linux-foundation.org> Message-ID: References: <1256650833-15516-1-git-send-email-mel@csn.ul.ie> <1256650833-15516-3-git-send-email-mel@csn.ul.ie> <20091027130924.fa903f5a.akpm@linux-foundation.org> User-Agent: Alpine 2.00 (DEB 1167 2008-08-23) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-System-Of-Record: true Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1436 Lines: 37 On Tue, 27 Oct 2009, Andrew Morton wrote: > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > > index dfa4362..7f2aa3e 100644 > > --- a/mm/page_alloc.c > > +++ b/mm/page_alloc.c > > @@ -1769,7 +1769,7 @@ gfp_to_alloc_flags(gfp_t gfp_mask) > > * See also cpuset_zone_allowed() comment in kernel/cpuset.c. > > */ > > alloc_flags &= ~ALLOC_CPUSET; > > - } else if (unlikely(rt_task(p))) > > + } else if (unlikely(rt_task(p)) && !in_interrupt()) > > alloc_flags |= ALLOC_HARDER; > > > > if (likely(!(gfp_mask & __GFP_NOMEMALLOC))) { > > What are the runtime-observeable effects of this change? > Giving rt tasks access to memory reserves is necessary to reduce latency, the privilege does not apply to interrupts that subsequently get run on the same cpu. > The description is a bit waffly-sounding for a -stable backportable > thing, IMO. What reason do the -stable maintainers and users have to > believe that this patch is needed, and an improvement? > Allowing interrupts to allocate below the low watermark when not GFP_ATOMIC depletes memory reserves; this fixes an inconsistency introduced by the page allocator refactoring patchset that went into 2.6.31. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/