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