Re: [patch 12/12] mm: correctly synchronize rss-counters atexit/exec

[Oleg Nesterov]

On 06/08, Konstantin Khlebnikov wrote:
>
> Oleg Nesterov wrote:
>> 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.
>
> Patch below broken: it removes one hunk from kernel/exit.c twice.
> And it does not add anything into mm_release().

Yes, sorry. But I guess you understand the intent, mm_release() should
simply do sync_mm_rss() after put_user(clear_child_tid) unconditionally.

If task->mm == NULL but task->rss_stat, then there is something wrong
and probably OOPS makes sense.

Oleg.

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/