Re: Linux 3.19-rc3

Linus Torvalds
2015-01-10T19:56:58Z

On Sat, Jan 10, 2015 at 11:47 AM, Laszlo Ersek <lersek@redhat.com> wrote:
>
> I grepped the tree for "fullmm", and only tlb_gather_mmu() seems to set
> it. There are several instances of that function, but each sets fullmm to:
>
> /* Is it from 0 to ~0? */
> tlb->fullmm = !(start | (end+1));
>
> So, a nonzero fullmm seems to imply (end == ~0UL).

Yes. But note how it imples "end == ~0ul", but it does *not* imply
"tlb->end" having that value.

tlb->end is initialized to zero (not obvious, but it's what the call
to __tlb_reset_range() does). It's then updated by
__tlb_adjust_range() as we actually flush individual pages.

Linus