From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ie0-f176.google.com (mail-ie0-f176.google.com [209.85.223.176]) by kanga.kvack.org (Postfix) with ESMTP id E6A186B0035 for ; Thu, 31 Jul 2014 18:57:06 -0400 (EDT) Received: by mail-ie0-f176.google.com with SMTP id tr6so4779508ieb.35 for ; Thu, 31 Jul 2014 15:57:06 -0700 (PDT) Received: from mail.linuxfoundation.org (mail.linuxfoundation.org. [140.211.169.12]) by mx.google.com with ESMTPS id r1si17749929icn.52.2014.07.31.15.57.05 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 31 Jul 2014 15:57:06 -0700 (PDT) Date: Thu, 31 Jul 2014 15:57:03 -0700 From: Andrew Morton Subject: Re: [PATCHv2] CMA/HOTPLUG: clear buffer-head lru before page migration Message-Id: <20140731155703.a8bc3b77af913c8b3a63090a@linux-foundation.org> In-Reply-To: <53D9A86B.20208@lge.com> References: <53D9A86B.20208@lge.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Gioh Kim Cc: =?UTF-8?Q?'=EA=B9=80=EC=A4=80=EC=88=98'?= , Marek Szyprowski , Minchan Kim , Laura Abbott , Michal Nazarewicz , Alexander Viro , Johannes Weiner , linux-kernel@vger.kernel.org, linux-mm@kvack.org, ????????? , 'Chanho Min' On Thu, 31 Jul 2014 11:22:35 +0900 Gioh Kim wrote: > The previous PATCH inserts invalidate_bh_lrus() only into CMA code. > HOTPLUG needs also dropping bh of lru. > So v2 inserts invalidate_bh_lrus() into both of CMA and HOTPLUG. > > > ---------------------------- 8< ---------------------------- > The bh must be free to migrate a page at which bh is mapped. > The reference count of bh is increased when it is installed > into lru so that the bh of lru must be freed before migrating the page. > > This frees every bh of lru. We could free only bh of migrating page. > But searching lru sometimes costs more than invalidating entire lru. > > Signed-off-by: Gioh Kim > Acked-by: Michal Nazarewicz > --- > mm/memory_hotplug.c | 1 + > mm/page_alloc.c | 2 ++ > 2 files changed, 3 insertions(+) > > diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c > index a3797d3..1c5454f 100644 > --- a/mm/memory_hotplug.c > +++ b/mm/memory_hotplug.c > @@ -1672,6 +1672,7 @@ repeat: > lru_add_drain_all(); > cond_resched(); > drain_all_pages(); > + invalidate_bh_lrus(); Both of these calls should have a comment explaining why invalidate_bh_lrus() is being called. > } > > pfn = scan_movable_pages(start_pfn, end_pfn); > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index b99643d4..c00dedf 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -6369,6 +6369,8 @@ int alloc_contig_range(unsigned long start, unsigned long end, > if (ret) > return ret; > > + invalidate_bh_lrus(); > + > ret = __alloc_contig_migrate_range(&cc, start, end); > if (ret) > goto done; I do feel that this change is likely to be beneficial, but I don't want to apply such a patch until I know what its effects are upon all alloc_contig_range() callers. Especially hugetlb. -- 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