Re: Some questions about linux kernel.

From: Khimenko Victor (khim@sch57.msk.ru)
Date: Sat Mar 11 2000 - 22:45:01 EST


In <Pine.LNX.4.21.0003111843320.29123-100000@duckman.conectiva> Rik van Riel (riel@conectiva.com.br) wrote:
RR> On Sat, 11 Mar 2000, Khimenko Victor wrote:

>> Ok. This discussion is serveral YEARS old. So do not hold you
>> breath. There were lots and lots of discussion about this and
>> fewdifferent patches are floating around for ages (in 2.2.15pre
>> some OOM patches was tried; perhaps 2.2.15 will include one of
>> them). But ALL patches are designed to help in case of run-away
>> process and NOT protect against malicious user.
>>
>> P.S. Of course if you'll be able to cook up patch and solve this
>> outstanding problem still not solved after few years of
>> exercises by Linux's memory wizards you are welcome. Just don't
>> think it's so easy :-(

RR> On the contrary, putting together a solution to this
RR> problem is easy.

It's not so. SOME solution is easy enough. But is it right solution ?
This is unclear. To many peoples ANY solution where ANY process can
be killed is "not right" -- theonly proper solution will be one where
you'll get NULL from malloc when there are not enough memory.

RR> The problem has been that people don't understand the issues involved
RR> and start a flamewar as soon as a patch (re)surfaces.

Exactly.

RR> Also, making a solution that everybody agrees with seems
RR> to be impossible in this situation :)

Ideal solution will be: solution where
  1) processes will be NEVER killed.
  2) if there are not enough memory malloc just return NULL.
  3) virtual memory is used effectively (that is almost 100% of memory+swap
     can be used for "real data").

AFAIK you can more or less satisfy any two items but not all three at once...

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