Re: [RFC] mmap(MAP_CONTIG)

[Christopher Lameter]

On Wed, 4 Oct 2017, Anshuman Khandual wrote:

> > - Using 'pre-allocated' pages in the fault paths may be intrusive.
>
> But we have already faulted in all of them for the mapping and they
> are also locked. Hence there should not be any page faults any more
> for the VMA. Am I missing something here ?

The PTEs may be torn down and have to reestablished through a page faults.
Page faults would not allocate memory.

> I am still wondering why wait till fault time not pre fault all of them
> and populate the page tables.

They are populated but some processes (swap and migration) may tear them
down.