Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758239AbZKTCR6 (ORCPT ); Thu, 19 Nov 2009 21:17:58 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1758201AbZKTCR5 (ORCPT ); Thu, 19 Nov 2009 21:17:57 -0500 Received: from mx1.redhat.com ([209.132.183.28]:7816 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758193AbZKTCR4 (ORCPT ); Thu, 19 Nov 2009 21:17:56 -0500 Date: Fri, 20 Nov 2009 03:11:02 +0100 From: Oleg Nesterov To: Jiri Slaby Cc: Ingo Molnar , Neil Horman , Stephen Rothwell , linux-kernel@vger.kernel.org, akpm@linux-foundation.org, marcin.slusarz@gmail.com, tglx@linutronix.de, mingo@redhat.com, hpa@zytor.com, Linus Torvalds Subject: acct_file_reopen() && do_acct_process() (Was: [PATCH 0/3] extend get/setrlimit to support setting rlimits external to a process (v7)) Message-ID: <20091120021102.GA5603@redhat.com> References: <20091106092600.GC22505@elte.hu> <4AF7D8C2.60807@gmail.com> <20091109090143.GB24020@elte.hu> <4AF83B9A.60702@gmail.com> <20091109164053.GB5160@redhat.com> <4AF84E2F.3010305@gmail.com> <20091109173654.GA8809@redhat.com> <4B040A03.2020508@gmail.com> <20091118231532.GA13039@redhat.com> <4B056791.5090002@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4B056791.5090002@gmail.com> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2011 Lines: 61 On 11/19, Jiri Slaby wrote: > > On 11/19/2009 12:15 AM, Oleg Nesterov wrote: > > On 11/18, Jiri Slaby wrote: > >> > >> kernel/acct.c: > >> /* > >> * Accounting records are not subject to resource limits. > >> */ > >> flim = current->signal->rlim[RLIMIT_FSIZE].rlim_cur; > >> current->signal->rlim[RLIMIT_FSIZE].rlim_cur = RLIM_INFINITY; > >> file->f_op->write(file, (char *)&ac, > >> sizeof(acct_t), &file->f_pos); > >> current->signal->rlim[RLIMIT_FSIZE].rlim_cur = flim; > >> > >> It means that threads of the process with PACCT caps have unlimited file > >> size for a short while. If there is setrlimit in between, it gets wiped > >> out as well. > > > > This is called when the whole thread-group exits, there are no > > live threads except current. > > Not really, it is called from umount, sys_acct and other paths. Hmm. you are right. Do you know why acct_file_reopen() does if (old_acct) do_acct_process(); ??? This looks just strange. What is the point ? If the caller doesn't exit, we shouldn't account it? And this is just wrong, no? Even if we forget about rlim, since do_acct_process() does override_creds() + revert_creds(), any __task_cred() in between is fooled? Probably I greatly misread something in acct.c, otherwise I can't see why, say, mntput() should ever record the caller in acct file. IOW: could someone explain why the patch below is wrong? Oleg. --- a/kernel/acct.c +++ b/kernel/acct.c @@ -206,7 +206,6 @@ static void acct_file_reopen(struct bsd_ if (old_acct) { mnt_unpin(old_acct->f_path.mnt); spin_unlock(&acct_lock); - do_acct_process(acct, old_ns, old_acct); filp_close(old_acct, NULL); spin_lock(&acct_lock); } -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/