From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx108.postini.com [74.125.245.108]) by kanga.kvack.org (Postfix) with SMTP id 45EFE6B0002 for ; Wed, 20 Feb 2013 09:22:59 -0500 (EST) Received: by mail-ie0-f175.google.com with SMTP id c12so9777636ieb.20 for ; Wed, 20 Feb 2013 06:22:58 -0800 (PST) MIME-Version: 1.0 In-Reply-To: <5124C6CF.1020001@gmail.com> References: <1359699013-7160-1-git-send-email-hannes@cmpxchg.org> <5124C6CF.1020001@gmail.com> Date: Wed, 20 Feb 2013 22:22:58 +0800 Message-ID: Subject: Re: [patch] mm: mlock: document scary-looking stack expansion mlock chain From: Michel Lespinasse Content-Type: text/plain; charset=ISO-8859-1 Sender: owner-linux-mm@kvack.org List-ID: To: Ric Mason Cc: Johannes Weiner , Andrew Morton , Alexander Viro , Hugh Dickins , linux-mm@kvack.org, linux-kernel@vger.kernel.org On Wed, Feb 20, 2013 at 8:51 PM, Ric Mason wrote: > On 02/01/2013 02:10 PM, Johannes Weiner wrote: >> >> The fact that mlock calls get_user_pages, and get_user_pages might >> call mlock when expanding a stack looks like a potential recursion. > > Why expand stack need call mlock? I can't find it in the codes, could you > point out to me? Its hidden in find_expand_vma(). Basically if the existing stack is already mlocked, any additional stack expansions get mlocked as well. -- Michel "Walken" Lespinasse A program is never fully debugged until the last user dies. -- 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/ . Don't email: email@kvack.org