From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx107.postini.com [74.125.245.107]) by kanga.kvack.org (Postfix) with SMTP id 509A66B007E for ; Mon, 2 Apr 2012 12:03:03 -0400 (EDT) Received: by bkwq16 with SMTP id q16so3130814bkw.14 for ; Mon, 02 Apr 2012 09:03:01 -0700 (PDT) Date: Mon, 2 Apr 2012 20:02:53 +0400 From: Cyrill Gorcunov Subject: Re: [PATCH 6/7] mm: kill vma flag VM_EXECUTABLE Message-ID: <20120402160253.GB15260@moon> 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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20120402144821.GA3334@redhat.com> Sender: owner-linux-mm@kvack.org List-ID: To: Oleg Nesterov Cc: Konstantin Khlebnikov , "linux-mm@kvack.org" , Andrew Morton , "linux-kernel@vger.kernel.org" , Eric Paris On Mon, Apr 02, 2012 at 04:48:21PM +0200, 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. So it leads to the same question -- do we *really* need the PR_SET_MM_EXE_FILE to be one-shot action? Yeah, I know, we agreed that one-shot is better than anything else from sysadmin perspective and such, but maybe I could introduce a special capability bit for c/r and allow a program which has such cap to modify exe-file without checkin mm_users? /me hides > > > set_mm_exe_file(current->mm, new_file); > > No, fput() can sleep. Sure, it was just "something like" as Konstantin stated, thanks anyway ;) Cyrill -- 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