From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wr0-f197.google.com (mail-wr0-f197.google.com [209.85.128.197]) by kanga.kvack.org (Postfix) with ESMTP id 51ACC6B0279 for ; Tue, 4 Jul 2017 02:51:17 -0400 (EDT) Received: by mail-wr0-f197.google.com with SMTP id v60so44627415wrc.7 for ; Mon, 03 Jul 2017 23:51:17 -0700 (PDT) Received: from mx1.suse.de (mx2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id u143si6598741wmu.44.2017.07.03.23.51.15 for (version=TLS1 cipher=AES128-SHA bits=128/128); Mon, 03 Jul 2017 23:51:16 -0700 (PDT) Date: Tue, 4 Jul 2017 08:51:12 +0200 From: Michal Hocko Subject: Re: "mm: use early_pfn_to_nid in page_ext_init" broken on some configurations? Message-ID: <20170704065112.GA12068@dhcp22.suse.cz> References: <20170630141847.GN22917@dhcp22.suse.cz> <20170630154224.GA9714@dhcp22.suse.cz> <20170630154416.GB9714@dhcp22.suse.cz> <20170704051138.GA28589@js1304-desktop> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170704051138.GA28589@js1304-desktop> Sender: owner-linux-mm@kvack.org List-ID: To: Joonsoo Kim Cc: Yang Shi , Mel Gorman , Andrew Morton , Vlastimil Babka , linux-mm@kvack.org, LKML On Tue 04-07-17 14:11:41, Joonsoo Kim wrote: > On Fri, Jun 30, 2017 at 05:44:16PM +0200, Michal Hocko wrote: > > On Fri 30-06-17 17:42:24, Michal Hocko wrote: > > [...] > > > diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h > > > index 16532fa0bb64..894697c1e6f5 100644 > > > --- a/include/linux/mmzone.h > > > +++ b/include/linux/mmzone.h > > > @@ -1055,6 +1055,7 @@ static inline struct zoneref *first_zones_zonelist(struct zonelist *zonelist, > > > !defined(CONFIG_HAVE_MEMBLOCK_NODE_MAP) > > > static inline unsigned long early_pfn_to_nid(unsigned long pfn) > > > { > > > + BUILD_BUG_ON(!IS_ENABLED(CONFIG_NUMA)); > > > > Err, this should read BUILD_BUG_ON(IS_ENABLED(CONFIG_NUMA)) of course > > Agreed. > > However, AFAIK, ARM can set CONFIG_NUMA but it doesn't have > CONFIG_HAVE_ARCH_EARLY_PFN_TO_NID and CONFIG_HAVE_MEMBLOCK_NODE_MAP. $ git grep "config NUMA\|select NUMA" arch/arm $ Did you mean arch64? If yes this one looks ok $ git grep "HAVE_MEMBLOCK_NODE_MAP\|HAVE_ARCH_EARLY_PFN_TO_NID" arch/arm64/ arch/arm64/Kconfig: select HAVE_MEMBLOCK_NODE_MAP if NUMA > If page_ext uses early_pfn_to_nid(), it will cause build error in ARM. Which would be intentional if it doesn't provide a proper implementation of the function. > Therefore, I suggest following change. > CONFIG_DEFERRED_STRUCT_PAGE_INIT depends on proper early_pfn_to_nid(). > So, following code will always work as long as > CONFIG_DEFERRED_STRUCT_PAGE_INIT works. I haven't checked all other callers of early_pfn_to_nid yet but I have run my original patch (with !IS_ENABLED...) just to see whether anybody actually uses this function from an innvalid context and it hasn't blown up. So I suspect that all current users simply use the function from the proper context. So if nobody objects I would just post the patch for inclusion. If the compilation breaks we can think of a proper implementation. > > Thanks. > > ----------->8--------------- > diff --git a/mm/page_ext.c b/mm/page_ext.c > index 88ccc044..e3db259 100644 > --- a/mm/page_ext.c > +++ b/mm/page_ext.c > @@ -384,6 +384,7 @@ void __init page_ext_init(void) > > for_each_node_state(nid, N_MEMORY) { > unsigned long start_pfn, end_pfn; > + int page_nid; > > start_pfn = node_start_pfn(nid); > end_pfn = node_end_pfn(nid); > @@ -405,8 +406,15 @@ void __init page_ext_init(void) > * > * Take into account DEFERRED_STRUCT_PAGE_INIT. > */ > - if (early_pfn_to_nid(pfn) != nid) > +#ifdef CONFIG_DEFERRED_STRUCT_PAGE_INIT > + page_nid = early_pfn_to_nid(pfn); > +#else > + page_nid = pfn_to_nid(pfn); > +#endif I cannot say I would be happy about this ifdefery. Especially when there is no existing user which would need it. > + > + if (page_nid != nid) > continue; > + > if (init_section_page_ext(pfn, nid)) > goto oom; > } -- Michal Hocko SUSE Labs -- 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