lkml.org 
[lkml]   [2010]   [Mar]   [30]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
SubjectRe: [PATCH] exit: fix oops in sync_mm_rss
On Tue, 30 Mar 2010 13:56:34 -0700
Andrew Morton <akpm@linux-foundation.org> wrote:

> That new BUG_ON() is triggering in Troels's machine when a bluetooth
> keyboard is enabled or disabled. See
> (https://bugzilla.kernel.org/show_bug.cgi?id=15648.
>
> I guess the question is: how did a kernel thread get a non-zero
> task->rss_stat.count[i]? If that's expected and OK then we will need
> to take some kernel-thread-avoidance action there.
>
It seems my fault that it's not initialized to be 0 at do_fork(), copy_process.

About do_exit, do_exit() does this check. So, tsk->mm can be NULL.

949 if (group_dead) {
950 hrtimer_cancel(&tsk->signal->real_timer);
951 exit_itimers(tsk->signal);
952 if (tsk->mm)
953 setmax_mm_hiwater_rss(&tsk->signal->maxrss, tsk->mm);
954 }

> Could whoever fixes this please also make __sync_task_rss_stat()
> static.
>
Ah, yes. I should do so.

> I'll toss this over to Rafael/Maciej for tracking as a post-2.6.33
> regression.
>
> Thanks.
>


==

task->rss_stat wasn't initialized to 0 at copy_process().
at exit, tsk->mm may be NULL.
And __sync_task_rss_stat() should be static.

Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
---
kernel/exit.c | 3 ++-
kernel/fork.c | 3 +++
mm/memory.c | 2 +-
3 files changed, 6 insertions(+), 2 deletions(-)

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);
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
@@ -124,7 +124,7 @@ 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;

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;



\
 
 \ /
  Last update: 2010-03-31 02:35    [W:0.194 / U:0.640 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site