* SeongJae Park <sj@xxxxxxxxxx> [230105 14:33]:
> Hi Liam,
>
> On Thu, 5 Jan 2023 19:16:00 +0000 Liam Howlett <liam.howlett@xxxxxxxxxx> wrote:
>
> > From: "Liam R. Howlett" <Liam.Howlett@xxxxxxxxxx>
> >
> > Prepare for the removal of the vma_mas_store() function by open coding
> > the maple tree store in this test code.
>
> But seems this series is not really removing 'vma_mas_store()'. Wouldn't it
> better to do the preparation and removal together in a same patch series?
It does from the all code but the nommu side. The definition is dropped
from the header and c file in "mmap: Convert __vma_adjust() to use vma
iterator" [1].
>
> > Set the range of the maple
> > state and call the store function directly.
> >
> > Cc: SeongJae Park <sj@xxxxxxxxxx>
> > Cc: damon@xxxxxxxxxxxxxxx
> > Reported-by: kernel test robot <lkp@xxxxxxxxx>
> > Signed-off-by: Liam R. Howlett <Liam.Howlett@xxxxxxxxxx>
> > ---
> > mm/damon/vaddr-test.h | 6 ++++--
> > 1 file changed, 4 insertions(+), 2 deletions(-)
> >
> > diff --git a/mm/damon/vaddr-test.h b/mm/damon/vaddr-test.h
> > index bce37c487540..41532f7355d0 100644
> > --- a/mm/damon/vaddr-test.h
> > +++ b/mm/damon/vaddr-test.h
> > @@ -24,8 +24,10 @@ static void __link_vmas(struct maple_tree *mt, struct vm_area_struct *vmas,
> > return;
> >
> > mas_lock(&mas);
> > - for (i = 0; i < nr_vmas; i++)
> > - vma_mas_store(&vmas[i], &mas);
> > + for (i = 0; i < nr_vmas; i++) {
> > + mas_set_range(&mas, vmas[i].vm_start, vmas[i].vm_end - 1);
> > + mas_store_gfp(&mas, &vmas[i], GFP_KERNEL);
> > + }
>
> On the latest mm-unstable, vma_mas_store() uses mas_store_prealloc() instead of
> mas_store_gfp(). Seems the difference would make no problem to this test code
> in most cases, but could I ask the reason for this change?
mas_store_prealloc() expects the maple state to have the necessary
memory to store the value. Using this function is the right way of
storing the range. In fact, we would only need a single node since
these values will be append operations anyways.
>
> Also, should we check the return value of mas_store_gfp()?
I can add this. The only reason we would return an error is on ENOMEM
which seems unlikely here. Again, it is a single node that will be
used. The size is 256B, but it's safer to add the check.
[1] https://lore.kernel.org/linux-mm/20230105191517.3099082-28-Liam.Howlett@xxxxxxxxxx/
Thanks,
Liam
