From 86169b00f89633e255048feb5dde438dd3522fd4 Mon Sep 17 00:00:00 2001 From: Vlastimil Babka Date: Mon, 15 Sep 2025 15:55:09 +0200 Subject: [PATCH] slab: wrap debug slab validation in validate_slab_ptr() This will make it clear where we currently cast struct slab to folio only to check the slab type, and allow to change the implementation later with memdesc conversion. For now use a struct page based implementation instead of struct folio to be compatible with further upcoming changes. Reviewed-by: Harry Yoo Signed-off-by: Vlastimil Babka --- mm/slub.c | 15 ++++++++++++--- 1 file changed, 12 insertions(+), 3 deletions(-) diff --git a/mm/slub.c b/mm/slub.c index 56143bfd1ae31..75e4388d507d1 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -821,6 +821,15 @@ static inline unsigned int get_orig_size(struct kmem_cache *s, void *object) return *(unsigned int *)p; } +/* + * For debugging context when we want to check if the struct slab pointer + * appears to be valid. + */ +static inline bool validate_slab_ptr(struct slab *slab) +{ + return PageSlab(slab_page(slab)); +} + #ifdef CONFIG_SLUB_DEBUG static unsigned long object_map[BITS_TO_LONGS(MAX_OBJS_PER_PAGE)]; static DEFINE_SPINLOCK(object_map_lock); @@ -1453,7 +1462,7 @@ static int check_slab(struct kmem_cache *s, struct slab *slab) { int maxobj; - if (!folio_test_slab(slab_folio(slab))) { + if (!validate_slab_ptr(slab)) { slab_err(s, slab, "Not a valid slab page"); return 0; } @@ -1653,7 +1662,7 @@ static noinline bool alloc_debug_processing(struct kmem_cache *s, return true; bad: - if (folio_test_slab(slab_folio(slab))) { + if (validate_slab_ptr(slab)) { /* * If this is a slab page then lets do the best we can * to avoid issues in the future. Marking all objects @@ -2818,7 +2827,7 @@ static void *alloc_single_from_partial(struct kmem_cache *s, slab->inuse++; if (!alloc_debug_processing(s, slab, object, orig_size)) { - if (folio_test_slab(slab_folio(slab))) + if (validate_slab_ptr(slab)) remove_partial(n, slab); return NULL; } -- 2.47.3