VM - is "reserved memory for root" possible (in case of a leak)?

[Tomasz Chmielewski]

Hello,

Short nature of a problem:

Recently I was playing with Apache2 as a proxy + mod_clamav as a virus 
scanner, put some load to it, and in a short time hanged the machine 
(actually, it was short of memory, and it stopped to respond - in logs I 
saw VM was killing some other processes, unfortunately not Apache).

As I could reach the machine only remotely, it was no wonder I run into 
troubles...

Sounds familiar?


Solution?

I was thinking, if there is something like:

"reserved_min_memory_for_root = 10M"
"reserved_min_memory_processes = /usr/sbin/sshd, /usr/sbin/pppd, etc.etc"

Which would just give that memory for those processes "once and for 
all", and thus, saving trouble in case of a memory leak, uncontrolled 
process, or similar.

I know it would be tricky to implement it, because the question arises, 
what happens if we have no memory left, and these 
"reserved_min_memory_processes" begin to grow?

But I think it would be something like a comparison:

ulimit vs this "reserved_min_memory_for_root", and
quota vs -m option from mke2fs.

Is there something like it already in the kernel?


It would be similar to mke2fs for the filesystem:

# man mke2fs

-m reserved-blocks-percentage
              Specify the percentage of the filesystem blocks reserved 
for the
              super-user.  This value defaults to 5%



Regards,

Tomasz Chmielewski

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