From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail144.messagelabs.com (mail144.messagelabs.com [216.82.254.51]) by kanga.kvack.org (Postfix) with ESMTP id 439DF6B0044 for ; Tue, 27 Oct 2009 17:12:48 -0400 (EDT) Received: from wpaz9.hot.corp.google.com (wpaz9.hot.corp.google.com [172.24.198.73]) by smtp-out.google.com with ESMTP id n9RLCfKt029254 for ; Tue, 27 Oct 2009 14:12:42 -0700 Received: from pzk37 (pzk37.prod.google.com [10.243.19.165]) by wpaz9.hot.corp.google.com with ESMTP id n9RLCLme020207 for ; Tue, 27 Oct 2009 14:12:38 -0700 Received: by pzk37 with SMTP id 37so96066pzk.10 for ; Tue, 27 Oct 2009 14:12:38 -0700 (PDT) Date: Tue, 27 Oct 2009 14:12:36 -0700 (PDT) From: David Rientjes 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> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org 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.orgMel Gorman List-ID: 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, 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