Re: [PATCH v2 01/15] mm/vma: introduce VMA virtual page offset field and add helpers

[Gregory Price]

On Mon, Jul 20, 2026 at 05:56:52PM +0100, Lorenzo Stoakes (ARM) wrote:
> On Mon, Jul 20, 2026 at 11:49:00AM -0400, Gregory Price wrote:
> > On Mon, Jul 20, 2026 at 03:38:27PM +0100, Lorenzo Stoakes (ARM) wrote:
> > >
> > > The virtual page offset of a VMA is equal to vma->vm_start >> PAGE_SHIFT if
> > > they are unfaulted or were not remapped, otherwise it is equal to this
> > > value at the point of first fault.
> > >
> >
> > The latter half of this description is a bit confusing.
> >
> > Why would the value differ from (vma->vm_start >> PAGE_SHIFT)?
> > (because it's file backed?
> 
> Because the VMA gets remapped.
> 
> If it's remapped when it's unfaulted, then virtual page offset gets updated, if
> it's faulted then not.
> 

ahhhhh the wording is just wonky then

when faulted or remapped, x is...
when unfaulted or unremapped, x is...

instead of

x is ... if unfaulted or were not remapped, otherwise...

Sort of a complex combination of 3 negatives there.

~Gregory