Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755341Ab3G2HYs (ORCPT ); Mon, 29 Jul 2013 03:24:48 -0400 Received: from mail-oa0-f41.google.com ([209.85.219.41]:35052 "EHLO mail-oa0-f41.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755258Ab3G2HYr (ORCPT ); Mon, 29 Jul 2013 03:24:47 -0400 MIME-Version: 1.0 In-Reply-To: <1375075929-6119-2-git-send-email-iamjoonsoo.kim@lge.com> References: <1375075929-6119-1-git-send-email-iamjoonsoo.kim@lge.com> <1375075929-6119-2-git-send-email-iamjoonsoo.kim@lge.com> Date: Mon, 29 Jul 2013 15:24:46 +0800 Message-ID: Subject: Re: [PATCH 01/18] mm, hugetlb: protect reserved pages when softofflining requests the pages From: Hillf Danton To: Joonsoo Kim Cc: Andrew Morton , Rik van Riel , Mel Gorman , Michal Hocko , "Aneesh Kumar K.V" , KAMEZAWA Hiroyuki , Hugh Dickins , Davidlohr Bueso , David Gibson , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Joonsoo Kim , Wanpeng Li , Naoya Horiguchi Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1273 Lines: 36 On Mon, Jul 29, 2013 at 1:31 PM, Joonsoo Kim wrote: > alloc_huge_page_node() use dequeue_huge_page_node() without > any validation check, so it can steal reserved page unconditionally. Well, why is it illegal to use reserved page here? > To fix it, check the number of free_huge_page in alloc_huge_page_node(). > > Signed-off-by: Joonsoo Kim > > diff --git a/mm/hugetlb.c b/mm/hugetlb.c > index 6782b41..d971233 100644 > --- a/mm/hugetlb.c > +++ b/mm/hugetlb.c > @@ -935,10 +935,11 @@ static struct page *alloc_buddy_huge_page(struct hstate *h, int nid) > */ > struct page *alloc_huge_page_node(struct hstate *h, int nid) > { > - struct page *page; > + struct page *page = NULL; > > spin_lock(&hugetlb_lock); > - page = dequeue_huge_page_node(h, nid); > + if (h->free_huge_pages - h->resv_huge_pages > 0) > + page = dequeue_huge_page_node(h, nid); > spin_unlock(&hugetlb_lock); > > if (!page) > -- > 1.7.9.5 > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/