From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752539Ab3IVAzM (ORCPT ); Sat, 21 Sep 2013 20:55:12 -0400 Received: from szxga03-in.huawei.com ([119.145.14.66]:47636 "EHLO szxga03-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752057Ab3IVAzK (ORCPT ); Sat, 21 Sep 2013 20:55:10 -0400 Message-ID: <523E3FC6.7020009@huawei.com> Date: Sun, 22 Sep 2013 08:54:30 +0800 From: Jianguo Wu User-Agent: Mozilla/5.0 (Windows NT 6.1; rv:12.0) Gecko/20120428 Thunderbird/12.0.1 MIME-Version: 1.0 To: Petr Holasek CC: Andrew Morton , Hugh Dickins , Mel Gorman , , Subject: Re: [PATCH] mm/ksm: return NULL when doesn't get mergeable page References: <5236FC88.6050409@huawei.com> <20130919083329.GA1620@thinkpad-work.brq.redhat.com> In-Reply-To: <20130919083329.GA1620@thinkpad-work.brq.redhat.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.135.74.216] X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2013/9/19 16:33, Petr Holasek wrote: > On Mon, 16 Sep 2013, Jianguo Wu wrote: >> In get_mergeable_page() local variable page is not initialized, >> it may hold a garbage value, when find_mergeable_vma() return NULL, >> get_mergeable_page() may return a garbage value to the caller. >> >> So initialize page as NULL. >> >> Signed-off-by: Jianguo Wu >> --- >> mm/ksm.c | 2 +- >> 1 files changed, 1 insertions(+), 1 deletions(-) >> >> diff --git a/mm/ksm.c b/mm/ksm.c >> index b6afe0c..87efbae 100644 >> --- a/mm/ksm.c >> +++ b/mm/ksm.c >> @@ -460,7 +460,7 @@ static struct page *get_mergeable_page(struct rmap_item *rmap_item) >> struct mm_struct *mm = rmap_item->mm; >> unsigned long addr = rmap_item->address; >> struct vm_area_struct *vma; >> - struct page *page; >> + struct page *page = NULL; >> >> down_read(&mm->mmap_sem); >> vma = find_mergeable_vma(mm, addr); >> -- >> 1.7.1 >> > > When find_mergeable_vma returned NULL, NULL is assigned to page in "out" > statement. > Oh, yes, thanks, Petr. >