Re: [PATCH] Prevent OOM from killing init

Jonathan Morton
2001-03-24T12:39:43Z

At 6:58 am +0000 24/3/2001, Rik van Riel wrote:
>On Sat, 24 Mar 2001, Jonathan Morton wrote:
>
>> Hmm... "if ( freemem < (size_of_mallocing_process / 20) )
>>fail_to_allocate;"
>>
>> Seems like a reasonable soft limit - processes which have already got
>> lots of RAM can probably stand not to have that little bit more and
>> can be curbed more quickly.
>
>This looks like it could nicely in preventing a single process
>from getting out of hand and gobbling up all memory.
>
>It won't prevent the system from a mongolian horde of processes,
>but nobody should expect your one-liner to fix world piece ;)
>
>I like it, now lets test it ;)

I thought of some things which could break it, which I want to try and deal
with before releasing a patch. Specifically, I want to make freepages.min
sacrosanct, so that malloc() *never* tries to use it. This should be
fairly easy to implement - simply subtract freepages.min from the freemem
part. An even nicer way would be to subtract freepages.low (or some
similar value) instead of freepages.min for non-root or non-privileged
processes.

BTW, is the 'current' pointer always valid when vm_enough_memory() is
called? If so, I can remove one redundant check.

My NetBSD friend appears to have found code in the BSD kernel which sets up
ulimit values sensibly by default - eg. it's not handled by the boot
scripts. Presumably a root process is capable of changing the limits, but
I'm guessing that sensible defaults in the kernel have to be a Good Thing.
Comments?

--------------------------------------------------------------
from: Jonathan "Chromatix" Morton
mail: chromi@cyberspace.org (not for attachments)
big-mail: chromatix@penguinpowered.com
uni-mail: j.d.morton@lancaster.ac.uk

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