Re: [PATCH v1 06/39] mm/rmap: add hugetlb sanity checks

Ryan Roberts
2023-12-11T16:30:06Z

On 11/12/2023 15:56, David Hildenbrand wrote:
> Let's make sure we end up with the right folios in the right functions.
>
> Signed-off-by: David Hildenbrand <david@redhat.com>

Reviewed-by: Ryan Roberts <ryan.roberts@arm.com>

> ---
> include/linux/rmap.h | 7 +++++++
> mm/rmap.c | 6 ++++++
> 2 files changed, 13 insertions(+)
>
> diff --git a/include/linux/rmap.h b/include/linux/rmap.h
> index 4c0650e9f6db..e3857d26b944 100644
> --- a/include/linux/rmap.h
> +++ b/include/linux/rmap.h
> @@ -217,6 +217,7 @@ void hugetlb_add_new_anon_rmap(struct folio *, struct vm_area_struct *,
> static inline int hugetlb_try_dup_anon_rmap(struct folio *folio,
> struct vm_area_struct *vma)
> {
> + VM_WARN_ON_FOLIO(!folio_test_hugetlb(folio), folio);
> VM_WARN_ON_FOLIO(!folio_test_anon(folio), folio);
>
> if (PageAnonExclusive(&folio->page)) {
> @@ -231,6 +232,7 @@ static inline int hugetlb_try_dup_anon_rmap(struct folio *folio,
> /* See page_try_share_anon_rmap() */
> static inline int hugetlb_try_share_anon_rmap(struct folio *folio)
> {
> + VM_WARN_ON_FOLIO(!folio_test_hugetlb(folio), folio);
> VM_WARN_ON_FOLIO(!folio_test_anon(folio), folio);
> VM_WARN_ON_FOLIO(!PageAnonExclusive(&folio->page), folio);
>
> @@ -253,6 +255,7 @@ static inline int hugetlb_try_share_anon_rmap(struct folio *folio)
>
> static inline void hugetlb_add_file_rmap(struct folio *folio)
> {
> + VM_WARN_ON_FOLIO(!folio_test_hugetlb(folio), folio);
> VM_WARN_ON_FOLIO(folio_test_anon(folio), folio);
>
> atomic_inc(&folio->_entire_mapcount);
> @@ -260,11 +263,15 @@ static inline void hugetlb_add_file_rmap(struct folio *folio)
>
> static inline void hugetlb_remove_rmap(struct folio *folio)
> {
> + VM_WARN_ON_FOLIO(!folio_test_hugetlb(folio), folio);
> +
> atomic_dec(&folio->_entire_mapcount);
> }
>
> static inline void __page_dup_rmap(struct page *page, bool compound)
> {
> + VM_WARN_ON(folio_test_hugetlb(page_folio(page)));
> +
> if (compound) {
> struct folio *folio = (struct folio *)page;
>
> diff --git a/mm/rmap.c b/mm/rmap.c
> index e210ac1b73de..41597da14f26 100644
> --- a/mm/rmap.c
> +++ b/mm/rmap.c
> @@ -1343,6 +1343,7 @@ void folio_add_new_anon_rmap(struct folio *folio, struct vm_area_struct *vma,
> {
> int nr = folio_nr_pages(folio);
>
> + VM_WARN_ON_FOLIO(folio_test_hugetlb(folio), folio);
> VM_BUG_ON_VMA(address < vma->vm_start ||
> address + (nr << PAGE_SHIFT) > vma->vm_end, vma);
> __folio_set_swapbacked(folio);
> @@ -1395,6 +1396,7 @@ void folio_add_file_rmap_range(struct folio *folio, struct page *page,
> unsigned int nr_pmdmapped = 0, first;
> int nr = 0;
>
> + VM_WARN_ON_FOLIO(folio_test_hugetlb(folio), folio);
> VM_WARN_ON_FOLIO(compound && !folio_test_pmd_mappable(folio), folio);
>
> /* Is page being mapped by PTE? Is this its first map to be added? */
> @@ -1480,6 +1482,7 @@ void page_remove_rmap(struct page *page, struct vm_area_struct *vma,
> bool last;
> enum node_stat_item idx;
>
> + VM_WARN_ON_FOLIO(folio_test_hugetlb(folio), folio);
> VM_BUG_ON_PAGE(compound && !PageHead(page), page);
>
> /* Is page being unmapped by PTE? Is this its last map to be removed? */
> @@ -2632,6 +2635,7 @@ void rmap_walk_locked(struct folio *folio, struct rmap_walk_control *rwc)
> void hugetlb_add_anon_rmap(struct folio *folio, struct vm_area_struct *vma,
> unsigned long address, rmap_t flags)
> {
> + VM_WARN_ON_FOLIO(!folio_test_hugetlb(folio), folio);
> VM_WARN_ON_FOLIO(!folio_test_anon(folio), folio);
>
> atomic_inc(&folio->_entire_mapcount);
> @@ -2644,6 +2648,8 @@ void hugetlb_add_anon_rmap(struct folio *folio, struct vm_area_struct *vma,
> void hugetlb_add_new_anon_rmap(struct folio *folio,
> struct vm_area_struct *vma, unsigned long address)
> {
> + VM_WARN_ON_FOLIO(!folio_test_hugetlb(folio), folio);
> +
> BUG_ON(address < vma->vm_start || address >= vma->vm_end);
> /* increment count (starts at -1) */
> atomic_set(&folio->_entire_mapcount, 0);