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SubjectForbid deletion of memory mappings
Date
Hi everyone!
I have a strange problem where I don't even know if there is a solution to it
at the moment:

I'm working on a new way of doing memory-management and currently I allocate
memory mappings (at non-fixed locations) in user-memory (i.e. < TASK_SIZE) in
addition to the regular pages mapped for the apps (e.g. heap memory, etc.)

It all works perfectly well (creating & deleting the additional mappings),
however, when the kernel feels like it needs to allocate a mapping in
user-space it sometimes deletes my mapping and overwrites it with the new
one, although there is plenty of free memory at some other location.

typically my mappings are (automatically chosen) located somewhere around
0xb7xxxxxx although there's plenty free space around 0xayyyyyyy. (i know that
this is a bad location because of stack, etc.) but i need the kernel to
choose a good location for me...
is there a way to make sure my mappings are not removed from memory?? or is
there a location where i can put my mappings that they will not be removed
(i.e. by using MAP_FIXED)?
Note that i need a big amount of memory so the range will have to be fairly
big (to be precise: i need a lot of 0x1000byte mappings - they are always
page-sized, not bigger, not smaller, but A LOT of them :-/ )

hope someone can help me with this!
thanks & greets,
Clemens
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