[PATCH 2/4] mm: speed up mremap by 500x on large regions (v2)

[Joel Fernandes]

On Wed, Oct 24, 2018 at 10:57:33PM +1100, Balbir Singh wrote:
[...]
> > > +		pmd_t pmd;
> > > +
> > > +		new_ptl = pmd_lockptr(mm, new_pmd);
> 
> 
> Looks like this is largely inspired by move_huge_pmd(), I guess a lot of
> the code applies, why not just reuse as much as possible? The same comments
> w.r.t mmap_sem helping protect against lock order issues applies as well.

I thought about this and when I looked into it, it seemed there are subtle
differences that make such sharing not worth it (or not possible).

 - Joel