slub: Add method to verify memory is not freed
This is for tracking down suspect memory usage.
Acked-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Ben Greear <greearb@candelatech.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
diff --git a/include/linux/slub_def.h b/include/linux/slub_def.h
index fd4fdc7..4b35c06 100644
--- a/include/linux/slub_def.h
+++ b/include/linux/slub_def.h
@@ -218,6 +218,19 @@
return ret;
}
+/**
+ * Calling this on allocated memory will check that the memory
+ * is expected to be in use, and print warnings if not.
+ */
+#ifdef CONFIG_SLUB_DEBUG
+extern bool verify_mem_not_deleted(const void *x);
+#else
+static inline bool verify_mem_not_deleted(const void *x)
+{
+ return true;
+}
+#endif
+
#ifdef CONFIG_TRACING
extern void *
kmem_cache_alloc_trace(struct kmem_cache *s, gfp_t gfpflags, size_t size);
diff --git a/mm/slub.c b/mm/slub.c
index c905099..0e4f4f8 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -2964,6 +2964,42 @@
}
EXPORT_SYMBOL(ksize);
+#ifdef CONFIG_SLUB_DEBUG
+bool verify_mem_not_deleted(const void *x)
+{
+ struct page *page;
+ void *object = (void *)x;
+ unsigned long flags;
+ bool rv;
+
+ if (unlikely(ZERO_OR_NULL_PTR(x)))
+ return false;
+
+ local_irq_save(flags);
+
+ page = virt_to_head_page(x);
+ if (unlikely(!PageSlab(page))) {
+ /* maybe it was from stack? */
+ rv = true;
+ goto out_unlock;
+ }
+
+ slab_lock(page);
+ if (on_freelist(page->slab, page, object)) {
+ object_err(page->slab, page, object, "Object is on free-list");
+ rv = false;
+ } else {
+ rv = true;
+ }
+ slab_unlock(page);
+
+out_unlock:
+ local_irq_restore(flags);
+ return rv;
+}
+EXPORT_SYMBOL(verify_mem_not_deleted);
+#endif
+
void kfree(const void *x)
{
struct page *page;