From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf0-f200.google.com (mail-pf0-f200.google.com [209.85.192.200]) by kanga.kvack.org (Postfix) with ESMTP id C0BFD6B025F for ; Thu, 14 Jul 2016 21:21:02 -0400 (EDT) Received: by mail-pf0-f200.google.com with SMTP id e189so187801014pfa.2 for ; Thu, 14 Jul 2016 18:21:02 -0700 (PDT) Received: from szxga03-in.huawei.com (szxga03-in.huawei.com. [119.145.14.66]) by mx.google.com with ESMTPS id 123si4050952pfg.205.2016.07.14.18.21.00 for (version=TLS1 cipher=AES128-SHA bits=128/128); Thu, 14 Jul 2016 18:21:02 -0700 (PDT) Message-ID: <57883A1F.8070600@huawei.com> Date: Fri, 15 Jul 2016 09:19:27 +0800 From: Xishi Qiu MIME-Version: 1.0 Subject: Re: [PATCH] mem-hotplug: use GFP_HIGHUSER_MOVABLE and alloc from next node in alloc_migrate_target() References: <5786F81B.1070502@huawei.com> In-Reply-To: Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: David Rientjes Cc: Andrew Morton , Vlastimil Babka , Joonsoo Kim , Naoya Horiguchi , Linux MM , LKML On 2016/7/15 6:17, David Rientjes wrote: > On Thu, 14 Jul 2016, Xishi Qiu wrote: > >> alloc_migrate_target() is called from migrate_pages(), and the page >> is always from user space, so we can add __GFP_HIGHMEM directly. >> >> Second, when we offline a node, the new page should alloced from other >> nodes instead of the current node, because re-migrate is a waste of >> time. >> > > alloc_migrate_target() is not only used from memory hotplug, it is also > used for CMA: we won't be isolating PageHuge() pages in > isolate_migratepages_range(), so this would cause a regression where we'd > be migrating memory to a remote NUMA node rather than preferring to > allocate locally. > > You may find it useful to use the 'private' field of the migrate_pages() > callback to specify the node the page should preferably be migrated to. > OK, I know, I'll rewrite v2. >> Signed-off-by: Xishi Qiu >> --- >> mm/page_isolation.c | 16 ++++++---------- >> 1 file changed, 6 insertions(+), 10 deletions(-) >> >> diff --git a/mm/page_isolation.c b/mm/page_isolation.c >> index 612122b..83848dc 100644 >> --- a/mm/page_isolation.c >> +++ b/mm/page_isolation.c >> @@ -282,20 +282,16 @@ int test_pages_isolated(unsigned long start_pfn, unsigned long end_pfn, >> struct page *alloc_migrate_target(struct page *page, unsigned long private, >> int **resultp) >> { >> - gfp_t gfp_mask = GFP_USER | __GFP_MOVABLE; >> - >> /* >> - * TODO: allocate a destination hugepage from a nearest neighbor node, >> + * TODO: allocate a destination page from a nearest neighbor node, >> * accordance with memory policy of the user process if possible. For >> * now as a simple work-around, we use the next node for destination. >> */ >> + int nid = next_node_in(page_to_nid(page), node_online_map); >> + >> if (PageHuge(page)) >> return alloc_huge_page_node(page_hstate(compound_head(page)), >> - next_node_in(page_to_nid(page), >> - node_online_map)); >> - >> - if (PageHighMem(page)) >> - gfp_mask |= __GFP_HIGHMEM; >> - >> - return alloc_page(gfp_mask); >> + nid); >> + else >> + return __alloc_pages_node(nid, GFP_HIGHUSER_MOVABLE, 0); > > I don't think this __alloc_pages_node() does what you think it does, it > only prefers nid here and will readily fallback to other nodes if > necessary. That is different than alloc_huge_page_node() which does no > fallback. So there's two issues with this change: (1) inconsistency > between PageHuge() and !PageHuge() behavior, and (2) the use of > __alloc_pages_node() does not match the commit description which states > "re-migrate is a waste of time." > Yes, you are right, how about change the changelog, one is membind, the other is prefer? Thanks, Xishi Qiu > . > -- 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