Hi Usama,
Let's use "mm/damon/paddr: " prefix for the patch title, to be more consistent
with others.
On Mon, 13 Jan 2025 18:03:40 +0000 Usama Arif <usamaarif642@xxxxxxxxx> wrote:
> This is to take into account for folios with size > 1 page.
> Iterating at PAGE_SIZE increment would increment sz_filter_passed
> multiple times for the same folio by folio_size, providing incorrect
> stats.
damon_get_folio() returns NULL if the page is a tail page. Hence I think it
will not increment sz_filter_passed multiple times?
> Hence go through the folio only once.
I tink this is still nice to do, for more efficiency. Can you post v2 of this
patch after updating the commit message and addressing below comments?
>
> Fixes: 6347f3385dd0 ("mm/damon/paddr: report filter-passed bytes back for DAMOS_STAT action")
> Signed-off-by: Usama Arif <usamaarif642@xxxxxxxxx>
> ---
> mm/damon/paddr.c | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/mm/damon/paddr.c b/mm/damon/paddr.c
> index 6b4397de4199..cc789a97c6f5 100644
> --- a/mm/damon/paddr.c
> +++ b/mm/damon/paddr.c
> @@ -504,7 +504,8 @@ static unsigned long damon_pa_stat(struct damon_region *r, struct damos *s,
> if (!damon_pa_scheme_has_filter(s))
> return 0;
>
> - for (addr = r->ar.start; addr < r->ar.end; addr += PAGE_SIZE) {
> + addr = r->ar.start;
> + while (addr < r->ar.end) {
> struct folio *folio = damon_get_folio(PHYS_PFN(addr));
>
> if (!folio)
In this case, the code does "continue". 'addr' is not advanced, so it will
result in an infinite loop. Let's do 'addr += PAGE_SIZE' here, to avoid that.
> @@ -515,6 +516,7 @@ static unsigned long damon_pa_stat(struct damon_region *r, struct damos *s,
> else
> *sz_filter_passed += folio_size(folio);
> put_folio:
> + addr += folio_size(folio);
> folio_put(folio);
> }
> return 0;
> --
> 2.43.5
Thanks,
SJ
