From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx167.postini.com [74.125.245.167]) by kanga.kvack.org (Postfix) with SMTP id 9277B6B004A for ; Wed, 18 Apr 2012 01:58:36 -0400 (EDT) Received: by lbbgp10 with SMTP id gp10so3765648lbb.14 for ; Tue, 17 Apr 2012 22:58:34 -0700 (PDT) Message-ID: <4F8E5807.6080909@openvz.org> Date: Wed, 18 Apr 2012 09:58:31 +0400 From: Konstantin Khlebnikov MIME-Version: 1.0 Subject: Re: [PATCH linux-next] mm/hugetlb: fix warning in alloc_huge_page/dequeue_huge_page_vma References: <20120417122819.7438.26117.stgit@zurg> <20120417135726.05de2546.akpm@linux-foundation.org> In-Reply-To: <20120417135726.05de2546.akpm@linux-foundation.org> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Andrew Morton Cc: "linux-mm@kvack.org" , "linux-kernel@vger.kernel.org" , Mel Gorman Andrew Morton wrote: > On Tue, 17 Apr 2012 16:28:19 +0400 > Konstantin Khlebnikov wrote: > >> This patch fixes gcc warning (and bug?) introduced in linux-next commit cc9a6c877 >> ("cpuset: mm: reduce large amounts of memory barrier related damage v3") >> >> Local variable "page" can be uninitialized if nodemask from vma policy does not >> intersects with nodemask from cpuset. Even if it wouldn't happens it's better to >> initialize this variable explicitly than to introduce kernel oops on weird corner case. >> >> mm/hugetlb.c: In function ___alloc_huge_page___: >> mm/hugetlb.c:1135:5: warning: ___page___ may be used uninitialized in this function >> >> ... >> >> --- a/mm/hugetlb.c >> +++ b/mm/hugetlb.c >> @@ -532,7 +532,7 @@ static struct page *dequeue_huge_page_vma(struct hstate *h, >> struct vm_area_struct *vma, >> unsigned long address, int avoid_reserve) >> { >> - struct page *page; >> + struct page *page = NULL; >> struct mempolicy *mpol; >> nodemask_t *nodemask; >> struct zonelist *zonelist; > > hm, that's a pretty blatant use-uninitialised bug. I wonder why so few > gcc versions report it. Mine doesn't. I'm using latest gcc-4.7 > > -- > 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/ -- 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 internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org