Re: [patch] cpusets: do not allow TIF_MEMDIE tasks to allocate globally

[David Rientjes <rientjes@google.com>]

On Tue, 5 Jun 2007, Christoph Lameter wrote:

> On Tue, 5 Jun 2007, David Rientjes wrote:
> 
> > Obviously GFP_KERNEL allocations can allocate regardless of our memory 
> > exclusivity, but the point is that a job in one exclusive cpuset should 
> > not have the ability to effect the performance (in terms of reclaim and 
> > swap), memory usage, or survival of jobs in other exclusive cpusets 
> > because it was out of memory.
> 
> Right but the process is terminating thus only requiring limited resources
> to get finished. The process does not have the ability to affect the other 
> cpusets. I.e. it cannot directly allocate outside of the cpuset. The 
> system has that capability and the system is handling the termination of 
> the process and should terminate the process in a clean way if possible.
> 

And those limited resources should be available in the difference between 
low and no watermarks as defined by each zone in the cpuset's 
mems_allowed.  Regardless, we should not allow allocations outside of the 
cpuset because we have marked it TIF_MEMDIE and we don't have any explicit 
guarantee that it is exiting yet and not mlock'ing an excessive amount of 
memory that exceeds the capacity of all cpuset nodes.

		David
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