[PATCH 07/62] mm: Use struct slab in kmem_obj_info()

["Matthew Wilcox (Oracle)" <willy@xxxxxxxxxxxxx>]

All three implementations of slab support kmem_obj_info() which reports
details of an object allocated from the slab allocator.  By using the
slab type instead of the page type, we make it obvious that this can
only be called for slabs.

Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
---
 mm/slab.c        | 12 ++++++------
 mm/slab.h        |  4 ++--
 mm/slab_common.c |  8 ++++----
 mm/slob.c        |  4 ++--
 mm/slub.c        | 12 ++++++------
 5 files changed, 20 insertions(+), 20 deletions(-)

diff --git a/mm/slab.c b/mm/slab.c
index d0f725637663..4a6bdbdcf0db 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -3657,21 +3657,21 @@ EXPORT_SYMBOL(__kmalloc_node_track_caller);
 #endif /* CONFIG_NUMA */
 
 #ifdef CONFIG_PRINTK
-void kmem_obj_info(struct kmem_obj_info *kpp, void *object, struct page *page)
+void kmem_obj_info(struct kmem_obj_info *kpp, void *object, struct slab *slab)
 {
 	struct kmem_cache *cachep;
 	unsigned int objnr;
 	void *objp;
 
 	kpp->kp_ptr = object;
-	kpp->kp_page = page;
-	cachep = page->slab_cache;
+	kpp->kp_slab = slab;
+	cachep = slab->slab_cache;
 	kpp->kp_slab_cache = cachep;
 	objp = object - obj_offset(cachep);
 	kpp->kp_data_offset = obj_offset(cachep);
-	page = virt_to_head_page(objp);
-	objnr = obj_to_index(cachep, page, objp);
-	objp = index_to_obj(cachep, page, objnr);
+	slab = virt_to_slab(objp);
+	objnr = obj_to_index(cachep, slab_page(slab), objp);
+	objp = index_to_obj(cachep, slab_page(slab), objnr);
 	kpp->kp_objp = objp;
 	if (DEBUG && cachep->flags & SLAB_STORE_USER)
 		kpp->kp_ret = *dbg_userword(cachep, objp);
diff --git a/mm/slab.h b/mm/slab.h
index ac89b656de67..29a0bf827a82 100644
--- a/mm/slab.h
+++ b/mm/slab.h
@@ -720,7 +720,7 @@ static inline void debugfs_slab_release(struct kmem_cache *s) { }
 #define KS_ADDRS_COUNT 16
 struct kmem_obj_info {
 	void *kp_ptr;
-	struct page *kp_page;
+	struct slab *kp_slab;
 	void *kp_objp;
 	unsigned long kp_data_offset;
 	struct kmem_cache *kp_slab_cache;
@@ -728,7 +728,7 @@ struct kmem_obj_info {
 	void *kp_stack[KS_ADDRS_COUNT];
 	void *kp_free_stack[KS_ADDRS_COUNT];
 };
-void kmem_obj_info(struct kmem_obj_info *kpp, void *object, struct page *page);
+void kmem_obj_info(struct kmem_obj_info *kpp, void *object, struct slab *slab);
 #endif
 
 #endif /* MM_SLAB_H */
diff --git a/mm/slab_common.c b/mm/slab_common.c
index ec2bb0beed75..c2605c77920b 100644
--- a/mm/slab_common.c
+++ b/mm/slab_common.c
@@ -587,18 +587,18 @@ void kmem_dump_obj(void *object)
 {
 	char *cp = IS_ENABLED(CONFIG_MMU) ? "" : "/vmalloc";
 	int i;
-	struct page *page;
+	struct slab *slab;
 	unsigned long ptroffset;
 	struct kmem_obj_info kp = { };
 
 	if (WARN_ON_ONCE(!virt_addr_valid(object)))
 		return;
-	page = virt_to_head_page(object);
-	if (WARN_ON_ONCE(!PageSlab(page))) {
+	slab = virt_to_slab(object);
+	if (WARN_ON_ONCE(!slab_test_cache(slab))) {
 		pr_cont(" non-slab memory.\n");
 		return;
 	}
-	kmem_obj_info(&kp, object, page);
+	kmem_obj_info(&kp, object, slab);
 	if (kp.kp_slab_cache)
 		pr_cont(" slab%s %s", cp, kp.kp_slab_cache->name);
 	else
diff --git a/mm/slob.c b/mm/slob.c
index 90996e8f7337..8cede39054fc 100644
--- a/mm/slob.c
+++ b/mm/slob.c
@@ -462,10 +462,10 @@ static void slob_free(void *block, int size)
 }
 
 #ifdef CONFIG_PRINTK
-void kmem_obj_info(struct kmem_obj_info *kpp, void *object, struct page *page)
+void kmem_obj_info(struct kmem_obj_info *kpp, void *object, struct slab *slab)
 {
 	kpp->kp_ptr = object;
-	kpp->kp_page = page;
+	kpp->kp_slab = slab;
 }
 #endif
 
diff --git a/mm/slub.c b/mm/slub.c
index 2780342395dc..517450561840 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -4290,31 +4290,31 @@ int __kmem_cache_shutdown(struct kmem_cache *s)
 }
 
 #ifdef CONFIG_PRINTK
-void kmem_obj_info(struct kmem_obj_info *kpp, void *object, struct page *page)
+void kmem_obj_info(struct kmem_obj_info *kpp, void *object, struct slab *slab)
 {
 	void *base;
 	int __maybe_unused i;
 	unsigned int objnr;
 	void *objp;
 	void *objp0;
-	struct kmem_cache *s = page->slab_cache;
+	struct kmem_cache *s = slab->slab_cache;
 	struct track __maybe_unused *trackp;
 
 	kpp->kp_ptr = object;
-	kpp->kp_page = page;
+	kpp->kp_slab = slab;
 	kpp->kp_slab_cache = s;
-	base = page_address(page);
+	base = slab_address(slab);
 	objp0 = kasan_reset_tag(object);
 #ifdef CONFIG_SLUB_DEBUG
 	objp = restore_red_left(s, objp0);
 #else
 	objp = objp0;
 #endif
-	objnr = obj_to_index(s, page, objp);
+	objnr = obj_to_index(s, slab_page(slab), objp);
 	kpp->kp_data_offset = (unsigned long)((char *)objp0 - (char *)objp);
 	objp = base + s->size * objnr;
 	kpp->kp_objp = objp;
-	if (WARN_ON_ONCE(objp < base || objp >= base + page->objects * s->size || (objp - base) % s->size) ||
+	if (WARN_ON_ONCE(objp < base || objp >= base + slab->objects * s->size || (objp - base) % s->size) ||
 	    !(s->flags & SLAB_STORE_USER))
 		return;
 #ifdef CONFIG_SLUB_DEBUG
-- 
2.32.0