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Message-ID: <4FBE0F23.3080903@openvz.org>
Date: Thu, 24 May 2012 14:36:19 +0400
From: Konstantin Khlebnikov <khlebnikov@...nvz.org>
To: Martin Mokrejs <mmokrejs@...d.natur.cuni.cz>
CC: Andrew Morton <akpm@...ux-foundation.org>,
LKML <linux-kernel@...r.kernel.org>,
"markus@...ppelsdorf.de" <markus@...ppelsdorf.de>,
"hughd@...gle.com" <hughd@...gle.com>,
"kamezawa.hiroyu@...fujitsu.com" <kamezawa.hiroyu@...fujitsu.com>,
"oleg@...hat.com" <oleg@...hat.com>, Michal Hocko <mhocko@...e.cz>,
"linux-mm@...ck.org" <linux-mm@...ck.org>
Subject: Re: 3.4-rc7: BUG: Bad rss-counter state mm:ffff88040b56f800 idx:1
val:-59
Martin Mokrejs wrote:
> Hi,
> I rebooted the laptop twice today after just brief uses and the messages did not
> appear in the logs.
>
> Now I just applied the below patch and during two reboots it did not appear either.
> Do I have to use the computer for some longer while to reproduce the issue? ;-)
Yes, some data must be in swap to reproduce this, so memory pressure required here.
>
> I will stay with the patch applied over 3.4-rc7 and would the BUG: re-appear I will
> let you know. But I doubt at the moment I could confirm it really helped.
> Clues how to reproduce? ;)
> Martin
>
> Andrew Morton wrote:
>> On Wed, 23 May 2012 00:41:28 +0200
>> Martin Mokrejs<mmokrejs@...d.natur.cuni.cz> wrote:
>>
>>> Hi Andrew,
>>> while shutting down my laptop (Dell Vostro 3550 with 16GB RAM, core i7) with 3.4-rc7 I got:
>>>
>>> May 23 00:07:54 vostro kernel: [352687.968267] BUG: Bad rss-counter state mm:ffff88040b56f800 idx:1 val:-59
>>> May 23 00:07:54 vostro kernel: [352687.968312] BUG: Bad rss-counter state mm:ffff88040b56f800 idx:2 val:59
>>> May 23 00:07:55 vostro acpid: exiting
>>> May 23 00:07:55 vostro syslog-ng[2838]: syslog-ng shutting down; version='3.3.4'
>>>
>>> I found by Google the below thread and thought that maybe it is related?
>>> http://comments.gmane.org/gmane.linux.kernel.mm/76459
>>>
>>> ...
>>>
>>
>>
>> Well hopefully the below will fix this?
>>
>> I notice that I don't have this tagged for -stable backporting. That
>> seems wrong. Konstantin, do we know for how long this bug has been in
>> there?
>>
>>
>>
>> From: Konstantin Khlebnikov<khlebnikov@...nvz.org>
>> Subject: mm: correctly synchronize rss-counters at exit/exec
>>
>> mm->rss_stat counters have per-task delta: task->rss_stat. Before
>> changing task->mm pointer the kernel must flush this delta with
>> sync_mm_rss().
>>
>> do_exit() already calls sync_mm_rss() to flush the rss-counters before
>> committing the rss statistics into task->signal->maxrss, taskstats, audit
>> and other stuff. Unfortunately the kernel does this before calling
>> mm_release(), which can call put_user() for processing
>> task->clear_child_tid. So at this point we can trigger page-faults and
>> task->rss_stat becomes non-zero again. As a result mm->rss_stat becomes
>> inconsistent and check_mm() will print something like this:
>>
>> | BUG: Bad rss-counter state mm:ffff88020813c380 idx:1 val:-1
>> | BUG: Bad rss-counter state mm:ffff88020813c380 idx:2 val:1
>>
>> This patch moves sync_mm_rss() into mm_release(), and moves mm_release()
>> out of do_exit() and calls it earlier. After mm_release() there should be
>> no pagefaults.
>>
>> [akpm@...ux-foundation.org: tweak comment]
>> Signed-off-by: Konstantin Khlebnikov<khlebnikov@...nvz.org>
>> Reported-by: Markus Trippelsdorf<markus@...ppelsdorf.de>
>> Cc: Hugh Dickins<hughd@...gle.com>
>> Cc: KAMEZAWA Hiroyuki<kamezawa.hiroyu@...fujitsu.com>
>> Cc: Oleg Nesterov<oleg@...hat.com>
>> Signed-off-by: Andrew Morton<akpm@...ux-foundation.org>
>> ---
>>
>> fs/exec.c | 1 -
>> kernel/exit.c | 13 ++++++++-----
>> kernel/fork.c | 8 ++++++++
>> 3 files changed, 16 insertions(+), 6 deletions(-)
>>
>> diff -puN fs/exec.c~mm-correctly-synchronize-rss-counters-at-exit-exec fs/exec.c
>> --- a/fs/exec.c~mm-correctly-synchronize-rss-counters-at-exit-exec
>> +++ a/fs/exec.c
>> @@ -823,7 +823,6 @@ static int exec_mmap(struct mm_struct *m
>> /* 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) {
>> diff -puN kernel/exit.c~mm-correctly-synchronize-rss-counters-at-exit-exec kernel/exit.c
>> --- a/kernel/exit.c~mm-correctly-synchronize-rss-counters-at-exit-exec
>> +++ a/kernel/exit.c
>> @@ -423,6 +423,7 @@ void daemonize(const char *name, ...)
>> * user space pages. We don't need them, and if we didn't close them
>> * they would be locked into memory.
>> */
>> + mm_release(current, current->mm);
>> exit_mm(current);
>> /*
>> * We don't want to get frozen, in case system-wide hibernation
>> @@ -640,7 +641,6 @@ static void exit_mm(struct task_struct *
>> struct mm_struct *mm = tsk->mm;
>> struct core_state *core_state;
>>
>> - mm_release(tsk, mm);
>> if (!mm)
>> return;
>> /*
>> @@ -959,9 +959,13 @@ void do_exit(long code)
>> preempt_count());
>>
>> acct_update_integrals(tsk);
>> - /* sync mm's RSS info before statistics gathering */
>> - if (tsk->mm)
>> - sync_mm_rss(tsk->mm);
>> +
>> + /* Set exit_code before complete_vfork_done() in mm_release() */
>> + tsk->exit_code = code;
>> +
>> + /* Release mm and sync mm's RSS info before statistics gathering */
>> + mm_release(tsk, tsk->mm);
>> +
>> group_dead = atomic_dec_and_test(&tsk->signal->live);
>> if (group_dead) {
>> hrtimer_cancel(&tsk->signal->real_timer);
>> @@ -974,7 +978,6 @@ void do_exit(long code)
>> tty_audit_exit();
>> audit_free(tsk);
>>
>> - tsk->exit_code = code;
>> taskstats_exit(tsk, group_dead);
>>
>> exit_mm(tsk);
>> diff -puN kernel/fork.c~mm-correctly-synchronize-rss-counters-at-exit-exec kernel/fork.c
>> --- a/kernel/fork.c~mm-correctly-synchronize-rss-counters-at-exit-exec
>> +++ a/kernel/fork.c
>> @@ -809,6 +809,14 @@ void mm_release(struct task_struct *tsk,
>> }
>> tsk->clear_child_tid = NULL;
>> }
>> +
>> + /*
>> + * Final rss-counter synchronization. After this point there must be
>> + * no pagefaults into this mm from the current context. Otherwise
>> + * mm->rss_stat will be inconsistent.
>> + */
>> + if (mm)
>> + sync_mm_rss(mm);
>> }
>>
>> /*
>> _
>>
>> .
>>
--
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