From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760409AbcBYLgR (ORCPT ); Thu, 25 Feb 2016 06:36:17 -0500 Received: from mail-wm0-f46.google.com ([74.125.82.46]:34124 "EHLO mail-wm0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750840AbcBYLgP (ORCPT ); Thu, 25 Feb 2016 06:36:15 -0500 Subject: Re: [PATCH] mm: remove __GFP_NOFAIL is deprecated comment To: Michal Hocko , Andrew Morton References: <1456397002-27172-1-git-send-email-mhocko@kernel.org> Cc: David Rientjes , linux-mm@kvack.org, LKML , Michal Hocko From: Nikolay Borisov Message-ID: <56CEE72B.5040009@kyup.com> Date: Thu, 25 Feb 2016 13:36:11 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.1.0 MIME-Version: 1.0 In-Reply-To: <1456397002-27172-1-git-send-email-mhocko@kernel.org> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 02/25/2016 12:43 PM, Michal Hocko wrote: > From: Michal Hocko > > 647757197cd3 ("mm: clarify __GFP_NOFAIL deprecation status") was > incomplete and didn't remove the comment about __GFP_NOFAIL being > deprecated in buffered_rmqueue. Let's get rid of this leftover > but keep the WARN_ON_ONCE for order > 1 because we should really > discourage from using __GFP_NOFAIL with higher order allocations > because those are just too subtle. > > Signed-off-by: Michal Hocko > --- > Hi, > this popped out when discussing another patch http://lkml.kernel.org/r/56CEC568.6080809@kyup.com > so I think it is worth removing the comment. > > mm/page_alloc.c | 18 +++++------------- > 1 file changed, 5 insertions(+), 13 deletions(-) > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index 1993894b4219..109d975a7172 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -2347,19 +2347,11 @@ struct page *buffered_rmqueue(struct zone *preferred_zone, > list_del(&page->lru); > pcp->count--; > } else { > - if (unlikely(gfp_flags & __GFP_NOFAIL)) { > - /* > - * __GFP_NOFAIL is not to be used in new code. > - * > - * All __GFP_NOFAIL callers should be fixed so that they > - * properly detect and handle allocation failures. > - * > - * We most definitely don't want callers attempting to > - * allocate greater than order-1 page units with > - * __GFP_NOFAIL. > - */ > - WARN_ON_ONCE(order > 1); > - } > + /* > + * We most definitely don't want callers attempting to > + * allocate greater than order-1 page units with __GFP_NOFAIL. > + */ > + WARN_ON_ONCE(unlikely(gfp_flags & __GFP_NOFAIL) && (order > 1)); WARN_ON_ONCE already includes an unlikely in its definition: http://lxr.free-electrons.com/source/include/asm-generic/bug.h#L109 > spin_lock_irqsave(&zone->lock, flags); > > page = NULL; > Reviewed-by: Nikolay Borisov