Re: Resurrecting the VM_PINNED discussion

[Eric B Munson]

On Tue, 03 Mar 2015, Vlastimil Babka wrote:

<snip>
> 
> No, you were correct and thanks for the hint. It's only ISOLATE_UNEVICTABLE from
> isolate_migratepages_range(), which is CMA, not regular compaction.
> But I wonder, can we change this even after VM_PINNED is introduced, if existing
> code depends on "no minor faults in mlocked areas", whatever the docs say? On
> the other hand, compaction is not the only source of migrations. I wonder what
> the NUMA balancing does (not) about mlocked areas...

My hope was that we could convince those that depend on mlock()
preventing minor faults to move to use the mpin() interface that was
discussed in the VM_PINNED thread.  If that is not acceptable then we
really need to update the man page for mlock() and the vm documentation
to be very clear that minor faults are also prevented.

Eric

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