From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail203.messagelabs.com (mail203.messagelabs.com [216.82.254.243]) by kanga.kvack.org (Postfix) with ESMTP id 5B0B56B0092 for ; Thu, 6 Jan 2011 15:39:38 -0500 (EST) Date: Thu, 6 Jan 2011 12:38:58 -0800 From: Andrew Morton Subject: Re: PATCH: hugetlb: handle NODEMASK_ALLOC failure correctly Message-Id: <20110106123858.8a585f77.akpm@linux-foundation.org> In-Reply-To: <20110106100439.GA5774@tiehlicka.suse.cz> References: <20110104105214.GA10759@tiehlicka.suse.cz> <907929848.134962.1294203162923.JavaMail.root@zmail06.collab.prod.int.phx2.redhat.com> <20110105084357.GA21349@tiehlicka.suse.cz> <20110105125959.c6e3d90a.akpm@linux-foundation.org> <20110106100439.GA5774@tiehlicka.suse.cz> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org To: Michal Hocko Cc: CAI Qian , linux-mm , Nishanth Aravamudan List-ID: On Thu, 6 Jan 2011 11:04:39 +0100 Michal Hocko wrote: > NODEMASK_ALLOC can use kmalloc if nodemask_t > 256 bytes so it might > fail with NULL as a result. Let's check the resulting variable and > fail with -ENOMEM if NODEMASK_ALLOC failed. > > Signed-off-by: Michal Hocko > --- > mm/hugetlb.c | 18 +++++++++++++++--- > 1 files changed, 15 insertions(+), 3 deletions(-) > > diff --git a/mm/hugetlb.c b/mm/hugetlb.c > index 4c0606c..21f31b2 100644 > --- a/mm/hugetlb.c > +++ b/mm/hugetlb.c > @@ -1439,14 +1439,19 @@ static ssize_t nr_hugepages_store_common(bool obey_mempolicy, > struct hstate *h; > NODEMASK_ALLOC(nodemask_t, nodes_allowed, GFP_KERNEL | __GFP_NORETRY); > > + if (!nodes_allowed) { > + err = -ENOMEM; > + goto out; > + } Looks good to me. I was going to complain that it adds extra unneeded instructions in the case where the nodemasks are allocated on the stack. But it appears that gcc assumes that stack-based variables cannot have address zero, so if gcc sees this: { nodemask_t foo; if (!&foo) { stuff } } if just removes it all for us. -- 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/ . Fight unfair telecom policy in Canada: sign http://dissolvethecrtc.ca/ Don't email: email@kvack.org