Commit 53238a60 authored by Catalin Marinas's avatar Catalin Marinas

kmemleak: Allow partial freeing of memory blocks

Functions like free_bootmem() are allowed to free only part of a memory
block. This patch adds support for this via the kmemleak_free_part()
callback which removes the original object and creates one or two
additional objects as a result of the memory block split.
Signed-off-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
Cc: Ingo Molnar <mingo@elte.hu>
Acked-by: default avatarPekka Enberg <penberg@cs.helsinki.fi>
parent e4f7c0b4
......@@ -27,6 +27,7 @@ extern void kmemleak_init(void);
extern void kmemleak_alloc(const void *ptr, size_t size, int min_count,
gfp_t gfp);
extern void kmemleak_free(const void *ptr);
extern void kmemleak_free_part(const void *ptr, size_t size);
extern void kmemleak_padding(const void *ptr, unsigned long offset,
size_t size);
extern void kmemleak_not_leak(const void *ptr);
......@@ -71,6 +72,9 @@ static inline void kmemleak_alloc_recursive(const void *ptr, size_t size,
static inline void kmemleak_free(const void *ptr)
{
}
static inline void kmemleak_free_part(const void *ptr, size_t size)
{
}
static inline void kmemleak_free_recursive(const void *ptr, unsigned long flags)
{
}
......
......@@ -210,6 +210,7 @@ static DEFINE_MUTEX(scan_mutex);
enum {
KMEMLEAK_ALLOC,
KMEMLEAK_FREE,
KMEMLEAK_FREE_PART,
KMEMLEAK_NOT_LEAK,
KMEMLEAK_IGNORE,
KMEMLEAK_SCAN_AREA,
......@@ -523,27 +524,17 @@ static void create_object(unsigned long ptr, size_t size, int min_count,
* Remove the metadata (struct kmemleak_object) for a memory block from the
* object_list and object_tree_root and decrement its use_count.
*/
static void delete_object(unsigned long ptr)
static void __delete_object(struct kmemleak_object *object)
{
unsigned long flags;
struct kmemleak_object *object;
write_lock_irqsave(&kmemleak_lock, flags);
object = lookup_object(ptr, 0);
if (!object) {
#ifdef DEBUG
kmemleak_warn("Freeing unknown object at 0x%08lx\n",
ptr);
#endif
write_unlock_irqrestore(&kmemleak_lock, flags);
return;
}
prio_tree_remove(&object_tree_root, &object->tree_node);
list_del_rcu(&object->object_list);
write_unlock_irqrestore(&kmemleak_lock, flags);
WARN_ON(!(object->flags & OBJECT_ALLOCATED));
WARN_ON(atomic_read(&object->use_count) < 1);
WARN_ON(atomic_read(&object->use_count) < 2);
/*
* Locking here also ensures that the corresponding memory block
......@@ -555,6 +546,64 @@ static void delete_object(unsigned long ptr)
put_object(object);
}
/*
* Look up the metadata (struct kmemleak_object) corresponding to ptr and
* delete it.
*/
static void delete_object_full(unsigned long ptr)
{
struct kmemleak_object *object;
object = find_and_get_object(ptr, 0);
if (!object) {
#ifdef DEBUG
kmemleak_warn("Freeing unknown object at 0x%08lx\n",
ptr);
#endif
return;
}
__delete_object(object);
put_object(object);
}
/*
* Look up the metadata (struct kmemleak_object) corresponding to ptr and
* delete it. If the memory block is partially freed, the function may create
* additional metadata for the remaining parts of the block.
*/
static void delete_object_part(unsigned long ptr, size_t size)
{
struct kmemleak_object *object;
unsigned long start, end;
object = find_and_get_object(ptr, 1);
if (!object) {
#ifdef DEBUG
kmemleak_warn("Partially freeing unknown object at 0x%08lx "
"(size %zu)\n", ptr, size);
#endif
return;
}
__delete_object(object);
/*
* Create one or two objects that may result from the memory block
* split. Note that partial freeing is only done by free_bootmem() and
* this happens before kmemleak_init() is called. The path below is
* only executed during early log recording in kmemleak_init(), so
* GFP_KERNEL is enough.
*/
start = object->pointer;
end = object->pointer + object->size;
if (ptr > start)
create_object(start, ptr - start, object->min_count,
GFP_KERNEL);
if (ptr + size < end)
create_object(ptr + size, end - ptr - size, object->min_count,
GFP_KERNEL);
put_object(object);
}
/*
* Make a object permanently as gray-colored so that it can no longer be
* reported as a leak. This is used in general to mark a false positive.
......@@ -719,12 +768,27 @@ void kmemleak_free(const void *ptr)
pr_debug("%s(0x%p)\n", __func__, ptr);
if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
delete_object((unsigned long)ptr);
delete_object_full((unsigned long)ptr);
else if (atomic_read(&kmemleak_early_log))
log_early(KMEMLEAK_FREE, ptr, 0, 0, 0, 0);
}
EXPORT_SYMBOL_GPL(kmemleak_free);
/*
* Partial memory freeing function callback. This function is usually called
* from bootmem allocator when (part of) a memory block is freed.
*/
void kmemleak_free_part(const void *ptr, size_t size)
{
pr_debug("%s(0x%p)\n", __func__, ptr);
if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
delete_object_part((unsigned long)ptr, size);
else if (atomic_read(&kmemleak_early_log))
log_early(KMEMLEAK_FREE_PART, ptr, size, 0, 0, 0);
}
EXPORT_SYMBOL_GPL(kmemleak_free_part);
/*
* Mark an already allocated memory block as a false positive. This will cause
* the block to no longer be reported as leak and always be scanned.
......@@ -1318,7 +1382,7 @@ static int kmemleak_cleanup_thread(void *arg)
rcu_read_lock();
list_for_each_entry_rcu(object, &object_list, object_list)
delete_object(object->pointer);
delete_object_full(object->pointer);
rcu_read_unlock();
mutex_unlock(&scan_mutex);
......@@ -1413,6 +1477,9 @@ void __init kmemleak_init(void)
case KMEMLEAK_FREE:
kmemleak_free(log->ptr);
break;
case KMEMLEAK_FREE_PART:
kmemleak_free_part(log->ptr, log->size);
break;
case KMEMLEAK_NOT_LEAK:
kmemleak_not_leak(log->ptr);
break;
......
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