From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail202.messagelabs.com (mail202.messagelabs.com [216.82.254.227]) by kanga.kvack.org (Postfix) with SMTP id B54E26B01EE for ; Tue, 30 Mar 2010 23:15:26 -0400 (EDT) Received: from m4.gw.fujitsu.co.jp ([10.0.50.74]) by fgwmail6.fujitsu.co.jp (Fujitsu Gateway) with ESMTP id o2V3FMTu018435 for (envelope-from kamezawa.hiroyu@jp.fujitsu.com); Wed, 31 Mar 2010 12:15:23 +0900 Received: from smail (m4 [127.0.0.1]) by outgoing.m4.gw.fujitsu.co.jp (Postfix) with ESMTP id 92C1745DE70 for ; Wed, 31 Mar 2010 12:15:22 +0900 (JST) Received: from s4.gw.fujitsu.co.jp (s4.gw.fujitsu.co.jp [10.0.50.94]) by m4.gw.fujitsu.co.jp (Postfix) with ESMTP id 5713545DE6F for ; Wed, 31 Mar 2010 12:15:22 +0900 (JST) Received: from s4.gw.fujitsu.co.jp (localhost.localdomain [127.0.0.1]) by s4.gw.fujitsu.co.jp (Postfix) with ESMTP id 2187BE18007 for ; Wed, 31 Mar 2010 12:15:22 +0900 (JST) Received: from m105.s.css.fujitsu.com (m105.s.css.fujitsu.com [10.249.87.105]) by s4.gw.fujitsu.co.jp (Postfix) with ESMTP id B15451DB803F for ; Wed, 31 Mar 2010 12:15:21 +0900 (JST) Date: Wed, 31 Mar 2010 12:11:20 +0900 From: KAMEZAWA Hiroyuki Subject: Re: [PATCH] exit: fix oops in sync_mm_rss Message-Id: <20100331121120.9bd35fd5.kamezawa.hiroyu@jp.fujitsu.com> In-Reply-To: <20100330200336.dd0ff9fd.akpm@linux-foundation.org> References: <20100316170808.GA29400@redhat.com> <20100330135634.09e6b045.akpm@linux-foundation.org> <20100331092815.c8b9d89c.kamezawa.hiroyu@jp.fujitsu.com> <20100330173721.cbd442cb.akpm@linux-foundation.org> <20100331094124.43c49290.kamezawa.hiroyu@jp.fujitsu.com> <20100330182258.59813fe6.akpm@linux-foundation.org> <20100331102755.92a89ca5.kamezawa.hiroyu@jp.fujitsu.com> <20100330200336.dd0ff9fd.akpm@linux-foundation.org> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org To: Andrew Morton Cc: Minchan Kim , "Michael S. Tsirkin" , cl@linux-foundation.org, lee.schermerhorn@hp.com, rientjes@google.com, Hugh Dickins , Rik van Riel , Andrea Arcangeli , "David S. Miller" , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Troels Liebe Bentsen , linux-bluetooth@vger.kernel.org List-ID: On Tue, 30 Mar 2010 20:03:36 -0400 Andrew Morton wrote: > On Wed, 31 Mar 2010 11:53:00 +0900 Minchan Kim wrote: > really. Apart from the fact that we'll otherwise perform an empty > NR_MM_COUNTERS loop in __sync_task_rss_stat(), sync_mm_rss() just isn't > set up to handle kernel threads. Given that the function of > sync_task_mm(from, to) is to move stuff from "from" and into "to", it's > daft to call it with a NULL value of `to'! > Updated again. == task->rss_stat wasn't initialized to 0 at copy_process(). At exit, tsk->mm may be NULL. It's not valid to call sync_mm_rss() against not exisiting mm_struct, We should check it. And __sync_task_rss_stat() should be static. This patch also removes BUG_ON(!mm) in __sync_task_rss_stat(). The code will panic if !mm without it. Changelog: - removed BUG_ON() - added check task->mm in exit.c before calling sync_mm_rss(). Reviewed-by: Minchan Kim Signed-off-by: KAMEZAWA Hiroyuki --- kernel/exit.c | 3 ++- kernel/fork.c | 3 +++ mm/memory.c | 3 +-- 3 files changed, 6 insertions(+), 3 deletions(-) Index: mmotm-2.6.34-Mar24/mm/memory.c =================================================================== --- mmotm-2.6.34-Mar24.orig/mm/memory.c +++ mmotm-2.6.34-Mar24/mm/memory.c @@ -124,13 +124,12 @@ core_initcall(init_zero_pfn); #if defined(SPLIT_RSS_COUNTING) -void __sync_task_rss_stat(struct task_struct *task, struct mm_struct *mm) +static void __sync_task_rss_stat(struct task_struct *task, struct mm_struct *mm) { int i; for (i = 0; i < NR_MM_COUNTERS; i++) { if (task->rss_stat.count[i]) { - BUG_ON(!mm); add_mm_counter(mm, i, task->rss_stat.count[i]); task->rss_stat.count[i] = 0; } Index: mmotm-2.6.34-Mar24/kernel/fork.c =================================================================== --- mmotm-2.6.34-Mar24.orig/kernel/fork.c +++ mmotm-2.6.34-Mar24/kernel/fork.c @@ -1060,6 +1060,9 @@ static struct task_struct *copy_process( p->prev_utime = cputime_zero; p->prev_stime = cputime_zero; #endif +#if defined(SPLIT_RSS_COUNTING) + memset(&p->rss_stat, 0, sizeof(p->rss_stat)); +#endif p->default_timer_slack_ns = current->timer_slack_ns; Index: mmotm-2.6.34-Mar24/kernel/exit.c =================================================================== --- mmotm-2.6.34-Mar24.orig/kernel/exit.c +++ mmotm-2.6.34-Mar24/kernel/exit.c @@ -950,7 +950,8 @@ NORET_TYPE void do_exit(long code) acct_update_integrals(tsk); /* sync mm's RSS info before statistics gathering */ - sync_mm_rss(tsk, tsk->mm); + if (tsk->mm) + sync_mm_rss(tsk, tsk->mm); group_dead = atomic_dec_and_test(&tsk->signal->live); if (group_dead) { hrtimer_cancel(&tsk->signal->real_timer); -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. 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