From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 40E18C4338F for ; Wed, 28 Jul 2021 12:42:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1B76B60F59 for ; Wed, 28 Jul 2021 12:42:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235220AbhG1Mmb (ORCPT ); Wed, 28 Jul 2021 08:42:31 -0400 Received: from smtp-out2.suse.de ([195.135.220.29]:39930 "EHLO smtp-out2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235244AbhG1Mma (ORCPT ); Wed, 28 Jul 2021 08:42:30 -0400 Received: from relay2.suse.de (relay2.suse.de [149.44.160.134]) by smtp-out2.suse.de (Postfix) with ESMTP id 8A6BA1FF9B; Wed, 28 Jul 2021 12:42:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1627476147; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=qE0e4wOwIM2Ykf5ORgyVCo3+kxWcajIMYmHfIA6nLmQ=; b=ntohU5YhnPckBDLRXy7jZyMABFIfjgtUiUSE+YSbG3Xy3cFXp6gLSSRYbXjtHRMsv68cT9 aA+XbhgIsRwtoVAgIiH72jPBHGRTZEWXkNim1tSR7v2W9KDF0vqslft7+NnEDkYdctGdkY wnFQaT9K3yli+1v+FyncTDMcP0GMbyE= Received: from suse.cz (unknown [10.100.201.86]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by relay2.suse.de (Postfix) with ESMTPS id 4EB51A3B83; Wed, 28 Jul 2021 12:42:27 +0000 (UTC) Date: Wed, 28 Jul 2021 14:42:26 +0200 From: Michal Hocko To: Feng Tang Cc: linux-mm@kvack.org, Andrew Morton , David Rientjes , Dave Hansen , Ben Widawsky , linux-kernel@vger.kernel.org, linux-api@vger.kernel.org, Andrea Arcangeli , Mel Gorman , Mike Kravetz , Randy Dunlap , Vlastimil Babka , Andi Kleen , Dan Williams , ying.huang@intel.com Subject: Re: [PATCH v6 2/6] mm/memplicy: add page allocation function for MPOL_PREFERRED_MANY policy Message-ID: References: <1626077374-81682-1-git-send-email-feng.tang@intel.com> <1626077374-81682-3-git-send-email-feng.tang@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1626077374-81682-3-git-send-email-feng.tang@intel.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon 12-07-21 16:09:30, Feng Tang wrote: > The semantics of MPOL_PREFERRED_MANY is similar to MPOL_PREFERRED, > that it will first try to allocate memory from the preferred node(s), > and fallback to all nodes in system when first try fails. > > Add a dedicated function for it just like 'interleave' policy. > > Link: https://lore.kernel.org/r/20200630212517.308045-9-ben.widawsky@intel.com > Suggested-by: Michal Hocko > Co-developed-by: Ben Widawsky > Signed-off-by: Ben Widawsky > Signed-off-by: Feng Tang It would be better to squash this together with the actual user of the function added by the next patch. > --- > mm/mempolicy.c | 19 +++++++++++++++++++ > 1 file changed, 19 insertions(+) > > diff --git a/mm/mempolicy.c b/mm/mempolicy.c > index 17b5800b7dcc..d17bf018efcc 100644 > --- a/mm/mempolicy.c > +++ b/mm/mempolicy.c > @@ -2153,6 +2153,25 @@ static struct page *alloc_page_interleave(gfp_t gfp, unsigned order, > return page; > } > > +static struct page *alloc_page_preferred_many(gfp_t gfp, unsigned int order, > + struct mempolicy *pol) We likely want a node parameter to know which one we want to start with for locality. Callers should use policy_node for that. > +{ > + struct page *page; > + > + /* > + * This is a two pass approach. The first pass will only try the > + * preferred nodes but skip the direct reclaim and allow the > + * allocation to fail, while the second pass will try all the > + * nodes in system. > + */ > + page = __alloc_pages(((gfp | __GFP_NOWARN) & ~__GFP_DIRECT_RECLAIM), > + order, first_node(pol->nodes), &pol->nodes); Although most users will likely have some form of GFP_*USER* here and clearing __GFP_DIRECT_RECLAIM will put all other reclaim modifiers out of game I think it would be better to explicitly disable some of them to prevent from surprises. E.g. any potential __GFP_NOFAIL would be more than surprising here. We do not have any (hopefully) but this should be pretty cheap to exclude as we already have to modify already. preferred_gfp = gfp | __GFP_NOWARN; preferred_gfp &= ~(__GFP_DIRECT_RECLAIM | __GFP_NOFAIL) > + if (!page) > + page = __alloc_pages(gfp, order, numa_node_id(), NULL); > + > + return page; > +} > + > /** > * alloc_pages_vma - Allocate a page for a VMA. > * @gfp: GFP flags. > -- > 2.7.4 -- Michal Hocko SUSE Labs