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Commit d18a90dd authored by Ben Greear's avatar Ben Greear Committed by Pekka Enberg
Browse files

slub: Add method to verify memory is not freed 



This is for tracking down suspect memory usage.

Acked-by: default avatarChristoph Lameter <cl@linux.com>
Signed-off-by: default avatarBen Greear <greearb@candelatech.com>
Signed-off-by: default avatarPekka Enberg <penberg@kernel.org>
parent d6543e39

include/linux/slub_def.h

+13 −0
Original line number Diff line number Diff line
@@ -218,6 +218,19 @@ kmalloc_order(size_t size, gfp_t flags, unsigned int order) 
	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);

mm/slub.c

+36 −0
Original line number Diff line number Diff line
@@ -2964,6 +2964,42 @@ size_t ksize(const void *object) 
}

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;