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

[Balbir Singh]

On Wed, Oct 24, 2018 at 07:13:50PM -0700, Joel Fernandes wrote:
> 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).
>

Could you elaborate on them?

Thanks,
Balbir Singh.