From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752301AbbCXOio (ORCPT ); Tue, 24 Mar 2015 10:38:44 -0400 Received: from cantor2.suse.de ([195.135.220.15]:56805 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752205AbbCXOim (ORCPT ); Tue, 24 Mar 2015 10:38:42 -0400 Message-ID: <1427207914.2412.17.camel@stgolabs.net> Subject: Re: [PATCH] mm: fix lockdep build in rcu-protected get_mm_exe_file() From: Davidlohr Bueso To: Oleg Nesterov Cc: Konstantin Khlebnikov , linux-mm@kvack.org, Andrew Morton , linux-kernel@vger.kernel.org Date: Tue, 24 Mar 2015 07:38:34 -0700 In-Reply-To: <20150323191055.GA10212@redhat.com> References: <20150320144715.24899.24547.stgit@buzz> <1427134273.2412.12.camel@stgolabs.net> <20150323191055.GA10212@redhat.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.12.9 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 2015-03-23 at 20:10 +0100, Oleg Nesterov wrote: > "atomic_read(&mm->mm_users) <= 1" looks a bit more "safe". But again, > I won't insist. Agreed, it is nicer to do that check, but I have no strong preference either, perhaps Konstantin or akpm do. Anyway, here's the change that can be folded in if you guys want to. Thanks. 8<------------------------------------------------- diff --git a/kernel/fork.c b/kernel/fork.c index 98858b5..0c3de2b 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -697,7 +697,7 @@ EXPORT_SYMBOL_GPL(mmput); void set_mm_exe_file(struct mm_struct *mm, struct file *new_exe_file) { struct file *old_exe_file = rcu_dereference_protected(mm->exe_file, - !atomic_read(&mm->mm_users) || current->in_execve); + atomic_read(&mm->mm_users) <= 1); if (new_exe_file) get_file(new_exe_file);