From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm0-f70.google.com (mail-wm0-f70.google.com [74.125.82.70]) by kanga.kvack.org (Postfix) with ESMTP id 4828A6B0278 for ; Wed, 21 Sep 2016 14:15:02 -0400 (EDT) Received: by mail-wm0-f70.google.com with SMTP id l132so31471227wmf.0 for ; Wed, 21 Sep 2016 11:15:02 -0700 (PDT) Received: from mx2.suse.de (mx2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id q1si9578958wma.87.2016.09.21.11.15.01 for (version=TLS1 cipher=AES128-SHA bits=128/128); Wed, 21 Sep 2016 11:15:01 -0700 (PDT) Date: Wed, 21 Sep 2016 20:14:58 +0200 From: Michal Hocko Subject: Re: [PATCH] mem-hotplug: Use nodes that contain memory as mask in new_node_page() Message-ID: <20160921181458.GJ24210@dhcp22.suse.cz> References: <1473044391.4250.19.camel@TP420> <20160912091811.GE14524@dhcp22.suse.cz> <1474447117.28370.6.camel@TP420> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1474447117.28370.6.camel@TP420> Sender: owner-linux-mm@kvack.org List-ID: To: Li Zhong Cc: David Rientjes , Vlastimil Babka , linux-mm , jallen@linux.vnet.ibm.com, qiuxishi@huawei.com, iamjoonsoo.kim@lge.com, n-horiguchi@ah.jp.nec.com, Andrew Morton , Tetsuo Handa On Wed 21-09-16 16:38:37, Li Zhong wrote: > Commit 9bb627be47a5 ("mem-hotplug: don't clear the only node in > new_node_page()") prevents allocating from an empty nodemask, but as David > points out, it is still wrong. As node_online_map may include memoryless > nodes, only allocating from these nodes is meaningless. > > This patch uses node_states[N_MEMORY] mask to prevent the above case. > OK, this is much better I believe this should have Fixes: 9bb627be47a5 ("mem-hotplug: don't clear the only node in new_node_page()") Fixes: 394e31d2ceb4 ("mem-hotplug: alloc new page from a nearest neighbor node when mem-offline") Fortunatelly everything is 4.8 so we do not need any backporting to stable. Anyway this just shows that the hotplug patches need much better review. E.g. 394e31d2ceb4 didn't have a single ack or r-b. Sigh > Signed-off-by: Li Zhong > --- > mm/memory_hotplug.c | 10 +++++----- > 1 file changed, 5 insertions(+), 5 deletions(-) > > diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c > index b58906b..9d29ba0 100644 > --- a/mm/memory_hotplug.c > +++ b/mm/memory_hotplug.c > @@ -1555,8 +1555,8 @@ static struct page *new_node_page(struct page *page, unsigned long private, > { > gfp_t gfp_mask = GFP_USER | __GFP_MOVABLE; > int nid = page_to_nid(page); > - nodemask_t nmask = node_online_map; > - struct page *new_page; > + nodemask_t nmask = node_states[N_MEMORY]; > + struct page *new_page = NULL; > > /* > * TODO: allocate a destination hugepage from a nearest neighbor node, > @@ -1567,14 +1567,14 @@ static struct page *new_node_page(struct page *page, unsigned long private, > return alloc_huge_page_node(page_hstate(compound_head(page)), > next_node_in(nid, nmask)); > > - if (nid != next_node_in(nid, nmask)) > - node_clear(nid, nmask); > + node_clear(nid, nmask); > > if (PageHighMem(page) > || (zone_idx(page_zone(page)) == ZONE_MOVABLE)) > gfp_mask |= __GFP_HIGHMEM; > > - new_page = __alloc_pages_nodemask(gfp_mask, 0, > + if (!nodes_empty(nmask)) > + new_page = __alloc_pages_nodemask(gfp_mask, 0, > node_zonelist(nid, gfp_mask), &nmask); > if (!new_page) > new_page = __alloc_pages(gfp_mask, 0, > -- 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