Commit 94f4a161 authored by Catalin Marinas's avatar Catalin Marinas Committed by Linus Torvalds

mm: kmemleak: treat vm_struct as alternative reference to vmalloc'ed objects

Kmemleak requires that vmalloc'ed objects have a minimum reference count
of 2: one in the corresponding vm_struct object and the other owned by
the vmalloc() caller.  There are cases, however, where the original
vmalloc() returned pointer is lost and, instead, a pointer to vm_struct
is stored (see free_thread_stack()).  Kmemleak currently reports such
objects as leaks.

This patch adds support for treating any surplus references to an object
as additional references to a specified object.  It introduces the
kmemleak_vmalloc() API function which takes a vm_struct pointer and sets
its surplus reference passing to the actual vmalloc() returned pointer.
The __vmalloc_node_range() calling site has been modified accordingly.

Link: http://lkml.kernel.org/r/1495726937-23557-4-git-send-email-catalin.marinas@arm.comSigned-off-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
Reported-by: default avatar"Luis R. Rodriguez" <mcgrof@kernel.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: "Luis R. Rodriguez" <mcgrof@kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 04f70d13
......@@ -150,6 +150,7 @@ See the include/linux/kmemleak.h header for the functions prototype.
- ``kmemleak_init`` - initialize kmemleak
- ``kmemleak_alloc`` - notify of a memory block allocation
- ``kmemleak_alloc_percpu`` - notify of a percpu memory block allocation
- ``kmemleak_vmalloc`` - notify of a vmalloc() memory allocation
- ``kmemleak_free`` - notify of a memory block freeing
- ``kmemleak_free_part`` - notify of a partial memory block freeing
- ``kmemleak_free_percpu`` - notify of a percpu memory block freeing
......
......@@ -22,6 +22,7 @@
#define __KMEMLEAK_H
#include <linux/slab.h>
#include <linux/vmalloc.h>
#ifdef CONFIG_DEBUG_KMEMLEAK
......@@ -30,6 +31,8 @@ extern void kmemleak_alloc(const void *ptr, size_t size, int min_count,
gfp_t gfp) __ref;
extern void kmemleak_alloc_percpu(const void __percpu *ptr, size_t size,
gfp_t gfp) __ref;
extern void kmemleak_vmalloc(const struct vm_struct *area, size_t size,
gfp_t gfp) __ref;
extern void kmemleak_free(const void *ptr) __ref;
extern void kmemleak_free_part(const void *ptr, size_t size) __ref;
extern void kmemleak_free_percpu(const void __percpu *ptr) __ref;
......@@ -81,6 +84,10 @@ static inline void kmemleak_alloc_percpu(const void __percpu *ptr, size_t size,
gfp_t gfp)
{
}
static inline void kmemleak_vmalloc(const struct vm_struct *area, size_t size,
gfp_t gfp)
{
}
static inline void kmemleak_free(const void *ptr)
{
}
......
......@@ -159,6 +159,8 @@ struct kmemleak_object {
atomic_t use_count;
unsigned long pointer;
size_t size;
/* pass surplus references to this pointer */
unsigned long excess_ref;
/* minimum number of a pointers found before it is considered leak */
int min_count;
/* the total number of pointers found pointing to this object */
......@@ -253,7 +255,8 @@ enum {
KMEMLEAK_NOT_LEAK,
KMEMLEAK_IGNORE,
KMEMLEAK_SCAN_AREA,
KMEMLEAK_NO_SCAN
KMEMLEAK_NO_SCAN,
KMEMLEAK_SET_EXCESS_REF
};
/*
......@@ -264,7 +267,10 @@ struct early_log {
int op_type; /* kmemleak operation type */
int min_count; /* minimum reference count */
const void *ptr; /* allocated/freed memory block */
union {
size_t size; /* memory block size */
unsigned long excess_ref; /* surplus reference passing */
};
unsigned long trace[MAX_TRACE]; /* stack trace */
unsigned int trace_len; /* stack trace length */
};
......@@ -562,6 +568,7 @@ static struct kmemleak_object *create_object(unsigned long ptr, size_t size,
object->flags = OBJECT_ALLOCATED;
object->pointer = ptr;
object->size = size;
object->excess_ref = 0;
object->min_count = min_count;
object->count = 0; /* white color initially */
object->jiffies = jiffies;
......@@ -794,6 +801,30 @@ static void add_scan_area(unsigned long ptr, size_t size, gfp_t gfp)
put_object(object);
}
/*
* Any surplus references (object already gray) to 'ptr' are passed to
* 'excess_ref'. This is used in the vmalloc() case where a pointer to
* vm_struct may be used as an alternative reference to the vmalloc'ed object
* (see free_thread_stack()).
*/
static void object_set_excess_ref(unsigned long ptr, unsigned long excess_ref)
{
unsigned long flags;
struct kmemleak_object *object;
object = find_and_get_object(ptr, 0);
if (!object) {
kmemleak_warn("Setting excess_ref on unknown object at 0x%08lx\n",
ptr);
return;
}
spin_lock_irqsave(&object->lock, flags);
object->excess_ref = excess_ref;
spin_unlock_irqrestore(&object->lock, flags);
put_object(object);
}
/*
* Set the OBJECT_NO_SCAN flag for the object corresponding to the give
* pointer. Such object will not be scanned by kmemleak but references to it
......@@ -908,7 +939,7 @@ static void early_alloc_percpu(struct early_log *log)
* @gfp: kmalloc() flags used for kmemleak internal memory allocations
*
* This function is called from the kernel allocators when a new object
* (memory block) is allocated (kmem_cache_alloc, kmalloc, vmalloc etc.).
* (memory block) is allocated (kmem_cache_alloc, kmalloc etc.).
*/
void __ref kmemleak_alloc(const void *ptr, size_t size, int min_count,
gfp_t gfp)
......@@ -951,6 +982,36 @@ void __ref kmemleak_alloc_percpu(const void __percpu *ptr, size_t size,
}
EXPORT_SYMBOL_GPL(kmemleak_alloc_percpu);
/**
* kmemleak_vmalloc - register a newly vmalloc'ed object
* @area: pointer to vm_struct
* @size: size of the object
* @gfp: __vmalloc() flags used for kmemleak internal memory allocations
*
* This function is called from the vmalloc() kernel allocator when a new
* object (memory block) is allocated.
*/
void __ref kmemleak_vmalloc(const struct vm_struct *area, size_t size, gfp_t gfp)
{
pr_debug("%s(0x%p, %zu)\n", __func__, area, size);
/*
* A min_count = 2 is needed because vm_struct contains a reference to
* the virtual address of the vmalloc'ed block.
*/
if (kmemleak_enabled) {
create_object((unsigned long)area->addr, size, 2, gfp);
object_set_excess_ref((unsigned long)area,
(unsigned long)area->addr);
} else if (kmemleak_early_log) {
log_early(KMEMLEAK_ALLOC, area->addr, size, 2);
/* reusing early_log.size for storing area->addr */
log_early(KMEMLEAK_SET_EXCESS_REF,
area, (unsigned long)area->addr, 0);
}
}
EXPORT_SYMBOL_GPL(kmemleak_vmalloc);
/**
* kmemleak_free - unregister a previously registered object
* @ptr: pointer to beginning of the object
......@@ -1248,6 +1309,7 @@ static void scan_block(void *_start, void *_end,
for (ptr = start; ptr < end; ptr++) {
struct kmemleak_object *object;
unsigned long pointer;
unsigned long excess_ref;
if (scan_should_stop())
break;
......@@ -1283,9 +1345,28 @@ static void scan_block(void *_start, void *_end,
* enclosed by scan_mutex.
*/
spin_lock_nested(&object->lock, SINGLE_DEPTH_NESTING);
/* only pass surplus references (object already gray) */
if (color_gray(object)) {
excess_ref = object->excess_ref;
/* no need for update_refs() if object already gray */
} else {
excess_ref = 0;
update_refs(object);
}
spin_unlock(&object->lock);
if (excess_ref) {
object = lookup_object(excess_ref, 0);
if (!object)
continue;
if (object == scanned)
/* circular reference, ignore */
continue;
spin_lock_nested(&object->lock, SINGLE_DEPTH_NESTING);
update_refs(object);
spin_unlock(&object->lock);
}
}
read_unlock_irqrestore(&kmemleak_lock, flags);
}
......@@ -1987,6 +2068,10 @@ void __init kmemleak_init(void)
case KMEMLEAK_NO_SCAN:
kmemleak_no_scan(log->ptr);
break;
case KMEMLEAK_SET_EXCESS_REF:
object_set_excess_ref((unsigned long)log->ptr,
log->excess_ref);
break;
default:
kmemleak_warn("Unknown early log operation: %d\n",
log->op_type);
......
......@@ -1770,12 +1770,7 @@ void *__vmalloc_node_range(unsigned long size, unsigned long align,
*/
clear_vm_uninitialized_flag(area);
/*
* A ref_count = 2 is needed because vm_struct allocated in
* __get_vm_area_node() contains a reference to the virtual address of
* the vmalloc'ed block.
*/
kmemleak_alloc(addr, real_size, 2, gfp_mask);
kmemleak_vmalloc(area, size, gfp_mask);
return addr;
......
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