On 24.10.24 05:23, Gaosheng Cui wrote:
The stable_tree_search() maybe return -EBUSY if the stable node's page is being migrated or nullptr, we need to check kfolio with IS_ERR_OR_NULL() before dereference it. To mitigate this, add IS_ERR_OR_NULL check for stable_tree_search(). Fixes: 15605244fdce ("ksm: convert cmp_and_merge_page() to use a folio") Signed-off-by: Gaosheng Cui <cuigaosheng1@xxxxxxxxxx> --- mm/ksm.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/mm/ksm.c b/mm/ksm.c index 4d482d011745..7ac59cde626c 100644 --- a/mm/ksm.c +++ b/mm/ksm.c @@ -1787,7 +1787,7 @@ static __always_inline struct folio *chain(struct ksm_stable_node **s_n_d, * with identical content to the page that we are scanning right now. * * This function returns the stable tree node of identical content if found, - * NULL otherwise. + * -EBUSY if the stable node's page is being migrated, NULL otherwise. */ static struct folio *stable_tree_search(struct page *page) { @@ -2261,7 +2261,8 @@ static void cmp_and_merge_page(struct page *page, struct ksm_rmap_item *rmap_ite/* Start by searching for the folio in the stable tree */kfolio = stable_tree_search(page); - if (&kfolio->page == page && rmap_item->head == stable_node) { + if (!IS_ERR_OR_NULL(kfolio) && &kfolio->page == page && + rmap_item->head == stable_node) { folio_put(kfolio); return; }
I'm late, but LGTM Acked-by: David Hildenbrand <david@xxxxxxxxxx> -- Cheers, David / dhildenb
