From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753173Ab2DBQUG (ORCPT ); Mon, 2 Apr 2012 12:20:06 -0400 Received: from mail-bk0-f46.google.com ([209.85.214.46]:38784 "EHLO mail-bk0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751960Ab2DBQUD (ORCPT ); Mon, 2 Apr 2012 12:20:03 -0400 Message-ID: <4F79D1AF.7080100@openvz.org> Date: Mon, 02 Apr 2012 20:19:59 +0400 From: Konstantin Khlebnikov User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:10.0.2) Gecko/20120217 Firefox/10.0.2 Iceape/2.7.2 MIME-Version: 1.0 To: Oleg Nesterov CC: Cyrill Gorcunov , "linux-mm@kvack.org" , Andrew Morton , "linux-kernel@vger.kernel.org" , Eric Paris Subject: Re: [PATCH 6/7] mm: kill vma flag VM_EXECUTABLE References: <20120331091049.19373.28994.stgit@zurg> <20120331092929.19920.54540.stgit@zurg> <20120331201324.GA17565@redhat.com> <20120331203912.GB687@moon> <4F79755B.3030703@openvz.org> <20120402144821.GA3334@redhat.com> In-Reply-To: <20120402144821.GA3334@redhat.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Oleg Nesterov wrote: > On 04/02, Konstantin Khlebnikov wrote: >> >> In this patch I leave mm->exe_file lockless. >> After exec/fork we can change it only for current task and only if mm->mm_users == 1. >> >> something like this: >> >> task_lock(current); > > OK, this protects against the race with get_task_mm() > >> if (atomic_read(¤t->mm->mm_users) == 1) > > this means PR_SET_MM_EXE_FILE can fail simply because someone did > get_task_mm(). Or the caller is multithreaded. This is sad, seems like we should keep mm->exe_file protection by mm->mmap_sem. So, I'll rework this patch... > >> set_mm_exe_file(current->mm, new_file); > > No, fput() can sleep. Yep > > Oleg. > > -- > 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