Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751880AbaFDSrz (ORCPT ); Wed, 4 Jun 2014 14:47:55 -0400 Received: from mail-ve0-f179.google.com ([209.85.128.179]:51170 "EHLO mail-ve0-f179.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751329AbaFDSrx (ORCPT ); Wed, 4 Jun 2014 14:47:53 -0400 MIME-Version: 1.0 In-Reply-To: <20140604182739.GA30340@kroah.com> References: <20140604182739.GA30340@kroah.com> Date: Wed, 4 Jun 2014 21:47:53 +0300 Message-ID: Subject: Re: Bad rss-counter is back on 3.14-stable From: Dennis Mungai To: Greg KH Cc: Dave Jones , linux-mm@kvack.org, Linux Kernel , Brandon Philips Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello Greg, 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: Greg KH Signed-off-by: Dennis E. Mungai --- fs/exec.c | 2 +- kernel/exit.c | 1 + 2 files changed, 2 insertions(+), 1 deletion(-) diff --git a/fs/exec.c b/fs/exec.c index a79786a..da27b91 100644 --- a/fs/exec.c +++ b/fs/exec.c @@ -819,10 +819,10 @@ static int exec_mmap(struct mm_struct *mm) /* Notify parent that we're no longer interested in the old VM */ tsk = current; old_mm = current->mm; - sync_mm_rss(old_mm); mm_release(tsk, old_mm); if (old_mm) { + sync_mm_rss(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 diff --git a/kernel/exit.c b/kernel/exit.c index 34867cc..c0277d3 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -643,6 +643,7 @@ static void exit_mm(struct task_struct * tsk) mm_release(tsk, mm); if (!mm) return; + sync_mm_rss(mm); /* * Serialize with any possible pending coredump. * We must hold mmap_sem around checking core_state Apply that patch and see how it goes. On 4 June 2014 21:27, Greg KH wrote: > Hi all, > > Dave, I saw you mention that you were seeing the "Bad rss-counter" line > on 3.15-rc1, but I couldn't find any follow-up on this to see if anyone > figured it out, or did it just "magically" go away? > > I ask as Brandon is seeing this same message a lot on a 3.14.4 kernel, > causing system crashes and problems: > > [16591492.449718] BUG: Bad rss-counter state mm:ffff8801ced99880 idx:0 val:-1836508 > [16591492.449737] BUG: Bad rss-counter state mm:ffff8801ced99880 idx:1 val:1836508 > > [20783350.461716] BUG: Bad rss-counter state mm:ffff8801d2b1dc00 idx:0 val:-52518 > [20783350.461734] BUG: Bad rss-counter state mm:ffff8801d2b1dc00 idx:1 val:52518 > > [21393387.112302] BUG: Bad rss-counter state mm:ffff8801d0104e00 idx:0 val:-1767569 > [21393387.112321] BUG: Bad rss-counter state mm:ffff8801d0104e00 idx:1 val:1767569 > > [21430098.512837] BUG: Bad rss-counter state mm:ffff880100036680 idx:0 val:-2946 > [21430098.512854] BUG: Bad rss-counter state mm:ffff880100036680 idx:1 val:2946 > > Anyone have any ideas of a 3.15-rc patch I should be including in > 3.14-stable to resolve this? > > thanks, > > greg k-h > -- > 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/ -- Please avoid sending me Word or PowerPoint attachments. See http://www.gnu.org/philosophy/no-word-attachments.html -- 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/