Re: [PATCH 1/2] mm: set task exit code before complete_vfork_done()

[Oleg Nesterov]

On 04/20, Konstantin Khlebnikov wrote:
>
> Oleg Nesterov wrote:
>>
>> 	/* sync mm's RSS info before statistics gathering */
>> 	if (tsk->mm)
>> 		sync_mm_rss(tsk->mm);
>>
>> Which "statistics gathering" ? Probably I missed something, but
>> after the quick grep it seems to me that this is only needed for
>> taskstats_exit()->xacct_add_tsk().
>>
>> So why we can't simply add sync_mm_rss() into xacct_add_tsk() ?
>
>> Yes, this way we do not "account" put_user(clear_child_tid) but
>> I think we do not care.
>
> Why we don't care? Each thread can corrupt these counters by one.
> I do not think that we are satisfied with nearly accurate rss accounting.
> +/- one page for each clone()-exit().

Not actually "for each" in practice. Each exit does sync_ (with
this patch from xacct_add_tsk), the net effect should be small.

And. This is what we do now, nobody ever complained.

>> IOW, what do you think about the trivial patch below? Uncompiled,
>> untested, probably incomplete. acct_update_integrals() looks
>> suspicious too.
>
> what a mess! =)

Thanks ;)

But it is much, much simpler than your patches, don't you agree?

Oleg.

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