From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx201.postini.com [74.125.245.201]) by kanga.kvack.org (Postfix) with SMTP id 1C2AB6B006C for ; Fri, 8 Jun 2012 08:26:46 -0400 (EDT) Date: Fri, 8 Jun 2012 14:24:59 +0200 From: Oleg Nesterov Subject: Re: [patch 12/12] mm: correctly synchronize rss-counters at exit/exec Message-ID: <20120608122459.GB23147@redhat.com> References: <20120607212114.E4F5AA02F8@akpm.mtv.corp.google.com> <4FD1D1F7.2090503@openvz.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4FD1D1F7.2090503@openvz.org> Sender: owner-linux-mm@kvack.org List-ID: To: Konstantin Khlebnikov Cc: Hugh Dickins , Linus Torvalds , "akpm@linux-foundation.org" , Linux Kernel Mailing List , linux-mm , "kamezawa.hiroyu@jp.fujitsu.com" , "markus@trippelsdorf.de" , "stable@vger.kernel.org" On 06/08, Konstantin Khlebnikov wrote: > > As result you can see "BUG: Bad rss-counter state mm:ffff88040783a680 idx:1 val:-1" in dmesg > > There left only one problem: nobody calls sync_mm_rss() after put_user() in mm_release(). Both callers call sync_mm_rss() to make check_mm() happy. But please see the changelog, I think we should move it into mm_release(). See the patch below (on top of v2 I sent). I need to recheck. As for xacct_add_tsk(), yes it can "miss" that put_user(). But this is what we have now, I think we do not care. Oleg. --- x/fs/exec.c +++ x/fs/exec.c @@ -822,7 +822,6 @@ static int exec_mmap(struct mm_struct *m 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 --- x/kernel/exit.c +++ x/kernel/exit.c @@ -656,7 +656,6 @@ static void exit_mm(struct task_struct * if (!mm) return; - sync_mm_rss(mm); /* * Serialize with any possible pending coredump. * We must hold mmap_sem around checking core_state --- x/kernel/taskstats.c +++ x/kernel/taskstats.c @@ -630,8 +630,7 @@ void taskstats_exit(struct task_struct * if (!stats) goto err; - if (tsk->mm) - sync_mm_rss(tsk->mm); + sync_mm_rss(tsk->mm); fill_stats(tsk, stats); /* --- x/kernel/exit.c +++ x/kernel/exit.c @@ -656,7 +656,6 @@ static void exit_mm(struct task_struct * if (!mm) return; - sync_mm_rss(mm); /* * Serialize with any possible pending coredump. * We must hold mmap_sem around checking core_state -- 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/ . Don't email: email@kvack.org