From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932552Ab2GASQp (ORCPT ); Sun, 1 Jul 2012 14:16:45 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:46985 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932319Ab2GASQj (ORCPT ); Sun, 1 Jul 2012 14:16:39 -0400 Message-Id: <20120701172008.252571630@decadent.org.uk> User-Agent: quilt/0.60-1 Date: Sun, 01 Jul 2012 18:20:17 +0100 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, Konstantin Khlebnikov , Markus Trippelsdorf , Oleg Nesterov , KAMEZAWA Hiroyuki , Hugh Dickins Subject: [ 11/48] mm: correctly synchronize rss-counters at exit/exec In-Reply-To: <20120701172006.535271340@decadent.org.uk> X-SA-Exim-Connect-IP: 2001:470:1f08:1539:21c:bfff:fe03:f805 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.2-stable review patch. If anyone has any objections, please let me know. ------------------ From: Konstantin Khlebnikov commit 4fe7efdbdfb1c7e7a7f31decfd831c0f31d37091 upstream. do_exit() and exec_mmap() call sync_mm_rss() before mm_release() does put_user(clear_child_tid) which can update task->rss_stat and thus make mm->rss_stat inconsistent. This triggers the "BUG:" printk in check_mm(). Let's fix this bug in the safest way, and optimize/cleanup this later. Reported-by: Markus Trippelsdorf Signed-off-by: Konstantin Khlebnikov Cc: Oleg Nesterov Cc: KAMEZAWA Hiroyuki Cc: Hugh Dickins Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds [bwh: Backported to 3.2: sync_mm_rss() still takes a struct task_struct *] Signed-off-by: Ben Hutchings --- --- a/fs/exec.c +++ b/fs/exec.c @@ -820,10 +820,10 @@ /* Notify parent that we're no longer interested in the old VM */ tsk = current; old_mm = current->mm; - sync_mm_rss(tsk, old_mm); mm_release(tsk, old_mm); if (old_mm) { + sync_mm_rss(tsk, old_mm); /* * Make sure that if there is a core dump in progress * for the old mm, we get out and die instead of going --- a/kernel/exit.c +++ b/kernel/exit.c @@ -641,6 +641,7 @@ mm_release(tsk, mm); if (!mm) return; + sync_mm_rss(tsk, mm); /* * Serialize with any possible pending coredump. * We must hold mmap_sem around checking core_state