On 23/10/2024 18:12, Zi Yan wrote:
> An anonymous large folio can be split into non order-0 folios,
> try_to_map_unused_to_zeropage() should not VM_BUG_ON compound pages but
> just return false. This fixes the crash when splitting anonymous large
> folios to non order-0 folios.
>
> Fixes: b1f202060afe ("mm: remap unused subpages to shared zeropage when splitting isolated thp")
> Signed-off-by: Zi Yan <ziy@xxxxxxxxxx>
> ---
> mm/migrate.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/mm/migrate.c b/mm/migrate.c
> index e950fd62607f..7ffdbe078aa7 100644
> --- a/mm/migrate.c
> +++ b/mm/migrate.c
> @@ -206,7 +206,8 @@ static bool try_to_map_unused_to_zeropage(struct page_vma_mapped_walk *pvmw,
> pte_t newpte;
> void *addr;
>
> - VM_BUG_ON_PAGE(PageCompound(page), page);
> + if (PageCompound(page))
> + return false;
> VM_BUG_ON_PAGE(!PageAnon(page), page);
> VM_BUG_ON_PAGE(!PageLocked(page), page);
> VM_BUG_ON_PAGE(pte_present(*pvmw->pte), page);
Thanks for fixing it!
Acked-by: Usama Arif <usamaarif642@xxxxxxxxx>
