On Wed 06-01-21 16:47:39, Muchun Song wrote:
> The page_huge_active() can be called from scan_movable_pages() which
> do not hold a reference count to the HugeTLB page. So when we call
> page_huge_active() from scan_movable_pages(), the HugeTLB page can
> be freed parallel. Then we will trigger a BUG_ON which is in the
> page_huge_active() when CONFIG_DEBUG_VM is enabled. Just remove the
> VM_BUG_ON_PAGE.
>
> Fixes: 7e1f049efb86 ("mm: hugetlb: cleanup using paeg_huge_active()")
> Signed-off-by: Muchun Song <songmuchun@xxxxxxxxxxxxx>
> Reviewed-by: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
Acked-by: Michal Hocko <mhocko@xxxxxxxx>
The BUG_ON looks like a wrong thing to do regardless of the memory
hotplug use. Which is admittedly ugly as well.
> ---
> mm/hugetlb.c | 1 -
> 1 file changed, 1 deletion(-)
>
> diff --git a/mm/hugetlb.c b/mm/hugetlb.c
> index 67200dd25b1d..7a24ed28ec4f 100644
> --- a/mm/hugetlb.c
> +++ b/mm/hugetlb.c
> @@ -1372,7 +1372,6 @@ struct hstate *size_to_hstate(unsigned long size)
> */
> bool page_huge_active(struct page *page)
> {
> - VM_BUG_ON_PAGE(!PageHuge(page), page);
> return PageHead(page) && PagePrivate(&page[1]);
> }
>
> --
> 2.11.0
--
Michal Hocko
SUSE Labs
