From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx163.postini.com [74.125.245.163]) by kanga.kvack.org (Postfix) with SMTP id 5FA376B004D for ; Wed, 4 Jan 2012 18:16:34 -0500 (EST) Date: Wed, 4 Jan 2012 15:16:32 -0800 From: Andrew Morton Subject: Re: [PATCH] mm: hugetlb: undo change to page mapcount in fault handler Message-Id: <20120104151632.05e6b3b0.akpm@linux-foundation.org> In-Reply-To: References: <20111222163604.GB14983@tiehlicka.suse.cz> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Hillf Danton Cc: Michal Hocko , linux-mm@kvack.org, LKML , KAMEZAWA Hiroyuki On Fri, 23 Dec 2011 21:00:41 +0800 Hillf Danton wrote: > Page mapcount should be updated only if we are sure that the page ends > up in the page table otherwise we would leak if we couldn't COW due to > reservations or if idx is out of bounds. It would be much nicer if we could run vma_needs_reservation() before even looking up or allocating the page. And afaict the interface is set up to do that: you run vma_needs_reservation() before allocating the page and then vma_commit_reservation() afterwards. But hugetlb_no_page() and hugetlb_fault() appear to have forgotten to run vma_commit_reservation() altogether. Why isn't this as busted as it appears to be? -- 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