Re: [PATCH 1/1] mm/madvise: enhance lazyfreeing with mTHP in madvise_free

Yin Fengwei
2024-02-26T02:38:39Z

On 1/1/70 08:00, wrote:
> diff --git a/mm/madvise.c b/mm/madvise.c
> index cfa5e7288261..bcbf56595a2e 100644
> --- a/mm/madvise.c
> +++ b/mm/madvise.c
> @@ -676,11 +676,43 @@ static int madvise_free_pte_range(pmd_t *pmd, unsigned long addr,
> */
> if (folio_test_large(folio)) {
> int err;
> + unsigned long next_addr, align;
>
> - if (folio_estimated_sharers(folio) != 1)
> - break;
> - if (!folio_trylock(folio))
> - break;
> + if (folio_estimated_sharers(folio) != 1 ||
> + !folio_trylock(folio))
> + goto skip_large_folio;
> +
> + align = folio_nr_pages(folio) * PAGE_SIZE;
> + next_addr = ALIGN_DOWN(addr + align, align);
There is a possible corner case:
If there is a cow folio associated with this folio and the cow folio
has smaller size than this folio for whatever reason, this change can't
handle it correctly.

Regards
Yin, Fengwei