Messages in this thread | | | Date | Wed, 26 Nov 1997 10:16:57 +0100 (MET) | From | Rik van Riel <> | Subject | Re: pageable page tables |
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On Tue, 25 Nov 1997, Ralf Baechle wrote:
> On Tue, Nov 25, 1997 at 09:37:00PM +0100, Rik van Riel wrote: > > > Another concern is that users can grab _all_ of system memory > > by having several processes do a 2GB mmap of /dev/zero... > > This 'doesn't take any memory' so they can take up as much > > (non-pageable) pagetable memory as they want. > > In fact, this is the main reason people asked me if I could look > > into this... This is one of the biggest denial-of-service holes > > still left. (ssstt) > > So the resource accounting should count those pages also.
That's not the point, as long as page-tables can't be swapped out, they will take up memory. Users sometimes have a memory quota as large as all of physical memory, which doesn't matter when things get swapped out. But when they take up memory by mmapping /dev/zero, their memory usage is completely _unswappable_
grtz,
Rik.
---------- Send Linux memory-management wishes to me: I'm currently looking for something to hack...
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