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kmemleak: use rbtree instead of prio tree 

kmemleak uses a tree where each node represents an allocated memory object
in order to quickly find out what object a given address is part of.
However, the objects don't overlap, so rbtrees are a better choice than
prio tree for this use.  They are both faster and have lower memory
overhead.

Tested by booting a kernel with kmemleak enabled, loading the
kmemleak_test module, and looking for the expected messages.

Signed-off-by: Michel Lespinasse <walken@google.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Hillf Danton <dhillf@gmail.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: David Woodhouse <dwmw2@infradead.org>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Tested-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Michel Lespinasse 2012-10-08 16:31:27 -07:00 committed by Linus Torvalds
parent 6b2dbba8b6
commit 85d3a316c7
1 changed files with 50 additions and 48 deletions
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98
mm/kmemleak.c
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@ -29,7 +29,7 @@
* - kmemleak_lock (rwlock): protects the object_list modifications and
* accesses to the object_tree_root. The object_list is the main list
* holding the metadata (struct kmemleak_object) for the allocated memory
* blocks. The object_tree_root is a priority search tree used to look-up
* blocks. The object_tree_root is a red black tree used to look-up
* metadata based on a pointer to the corresponding memory block. The
* kmemleak_object structures are added to the object_list and
* object_tree_root in the create_object() function called from the
@ -71,7 +71,7 @@
#include <linux/delay.h>
#include <linux/export.h>
#include <linux/kthread.h>
#include <linux/prio_tree.h>
#include <linux/rbtree.h>
#include <linux/fs.h>
#include <linux/debugfs.h>
#include <linux/seq_file.h>
@ -132,7 +132,7 @@ struct kmemleak_scan_area {
* Structure holding the metadata for each allocated memory block.
* Modifications to such objects should be made while holding the
* object->lock. Insertions or deletions from object_list, gray_list or
* tree_node are already protected by the corresponding locks or mutex (see
* rb_node are already protected by the corresponding locks or mutex (see
* the notes on locking above). These objects are reference-counted
* (use_count) and freed using the RCU mechanism.
*/
@ -141,7 +141,7 @@ struct kmemleak_object {
unsigned long flags; /* object status flags */
struct list_head object_list;
struct list_head gray_list;
struct prio_tree_node tree_node;
struct rb_node rb_node;
struct rcu_head rcu; /* object_list lockless traversal */
/* object usage count; object freed when use_count == 0 */
atomic_t use_count;
@ -182,9 +182,9 @@ struct kmemleak_object {
static LIST_HEAD(object_list);
/* the list of gray-colored objects (see color_gray comment below) */
static LIST_HEAD(gray_list);
/* prio search tree for object boundaries */
static struct prio_tree_root object_tree_root;
/* rw_lock protecting the access to object_list and prio_tree_root */
/* search tree for object boundaries */
static struct rb_root object_tree_root = RB_ROOT;
/* rw_lock protecting the access to object_list and object_tree_root */
static DEFINE_RWLOCK(kmemleak_lock);
/* allocation caches for kmemleak internal data */
@ -380,7 +380,7 @@ static void dump_object_info(struct kmemleak_object *object)
trace.entries = object->trace;
pr_notice("Object 0x%08lx (size %zu):\n",
object->tree_node.start, object->size);
object->pointer, object->size);
pr_notice(" comm \"%s\", pid %d, jiffies %lu\n",
object->comm, object->pid, object->jiffies);
pr_notice(" min_count = %d\n", object->min_count);
@ -392,32 +392,32 @@ static void dump_object_info(struct kmemleak_object *object)
}
/*
* Look-up a memory block metadata (kmemleak_object) in the priority search
* Look-up a memory block metadata (kmemleak_object) in the object search
* tree based on a pointer value. If alias is 0, only values pointing to the
* beginning of the memory block are allowed. The kmemleak_lock must be held
* when calling this function.
*/
static struct kmemleak_object *lookup_object(unsigned long ptr, int alias)
{
struct prio_tree_node *node;
struct prio_tree_iter iter;
struct kmemleak_object *object;
struct rb_node *rb = object_tree_root.rb_node;
prio_tree_iter_init(&iter, &object_tree_root, ptr, ptr);
node = prio_tree_next(&iter);
if (node) {
object = prio_tree_entry(node, struct kmemleak_object,
tree_node);
if (!alias && object->pointer != ptr) {
while (rb) {
struct kmemleak_object *object =
rb_entry(rb, struct kmemleak_object, rb_node);
if (ptr < object->pointer)
rb = object->rb_node.rb_left;
else if (object->pointer + object->size <= ptr)
rb = object->rb_node.rb_right;
else if (object->pointer == ptr || alias)
return object;
else {
kmemleak_warn("Found object by alias at 0x%08lx\n",
ptr);
dump_object_info(object);
object = NULL;
break;
}
} else
object = NULL;
return object;
}
return NULL;
}
/*
@ -471,7 +471,7 @@ static void put_object(struct kmemleak_object *object)
}
/*
* Look up an object in the prio search tree and increase its use_count.
* Look up an object in the object search tree and increase its use_count.
*/
static struct kmemleak_object *find_and_get_object(unsigned long ptr, int alias)
{
@ -516,8 +516,8 @@ static struct kmemleak_object *create_object(unsigned long ptr, size_t size,
int min_count, gfp_t gfp)
{
unsigned long flags;
struct kmemleak_object *object;
struct prio_tree_node *node;
struct kmemleak_object *object, *parent;
struct rb_node **link, *rb_parent;
object = kmem_cache_alloc(object_cache, gfp_kmemleak_mask(gfp));
if (!object) {
@ -560,31 +560,34 @@ static struct kmemleak_object *create_object(unsigned long ptr, size_t size,
/* kernel backtrace */
object->trace_len = __save_stack_trace(object->trace);
INIT_PRIO_TREE_NODE(&object->tree_node);
object->tree_node.start = ptr;
object->tree_node.last = ptr + size - 1;
write_lock_irqsave(&kmemleak_lock, flags);
min_addr = min(min_addr, ptr);
max_addr = max(max_addr, ptr + size);
node = prio_tree_insert(&object_tree_root, &object->tree_node);
/*
* The code calling the kernel does not yet have the pointer to the
* memory block to be able to free it. However, we still hold the
* kmemleak_lock here in case parts of the kernel started freeing
* random memory blocks.
*/
if (node != &object->tree_node) {
kmemleak_stop("Cannot insert 0x%lx into the object search tree "
"(already existing)\n", ptr);
object = lookup_object(ptr, 1);
spin_lock(&object->lock);
dump_object_info(object);
spin_unlock(&object->lock);
goto out;
link = &object_tree_root.rb_node;
rb_parent = NULL;
while (*link) {
rb_parent = *link;
parent = rb_entry(rb_parent, struct kmemleak_object, rb_node);
if (ptr + size <= parent->pointer)
link = &parent->rb_node.rb_left;
else if (parent->pointer + parent->size <= ptr)
link = &parent->rb_node.rb_right;
else {
kmemleak_stop("Cannot insert 0x%lx into the object "
"search tree (overlaps existing)\n",
ptr);
kmem_cache_free(object_cache, object);
object = parent;
spin_lock(&object->lock);
dump_object_info(object);
spin_unlock(&object->lock);
goto out;
}
}
rb_link_node(&object->rb_node, rb_parent, link);
rb_insert_color(&object->rb_node, &object_tree_root);
list_add_tail_rcu(&object->object_list, &object_list);
out:
write_unlock_irqrestore(&kmemleak_lock, flags);
@ -600,7 +603,7 @@ static void __delete_object(struct kmemleak_object *object)
unsigned long flags;
write_lock_irqsave(&kmemleak_lock, flags);
prio_tree_remove(&object_tree_root, &object->tree_node);
rb_erase(&object->rb_node, &object_tree_root);
list_del_rcu(&object->object_list);
write_unlock_irqrestore(&kmemleak_lock, flags);
@ -1766,7 +1769,6 @@ void __init kmemleak_init(void)
object_cache = KMEM_CACHE(kmemleak_object, SLAB_NOLEAKTRACE);
scan_area_cache = KMEM_CACHE(kmemleak_scan_area, SLAB_NOLEAKTRACE);
INIT_PRIO_TREE_ROOT(&object_tree_root);
if (crt_early_log >= ARRAY_SIZE(early_log))
pr_warning("Early log buffer exceeded (%d), please increase "