From: Zhaoyang Huang <zhaoyang.huang@xxxxxxxxxx>
Introduce a set of methods to account object via backtrace.
Signed-off-by: Zhaoyang Huang <zhaoyang.huang@xxxxxxxxxx>
---
include/linux/slub_def.h | 7 +++
mm/slub.c | 155 ++++++++++++++++++++++++++++++++++++++++++++++-
2 files changed, 161 insertions(+), 1 deletion(-)
diff --git a/include/linux/slub_def.h b/include/linux/slub_def.h
index f9c68a9..c90e5fb 100644
--- a/include/linux/slub_def.h
+++ b/include/linux/slub_def.h
@@ -139,9 +139,16 @@ struct kmem_cache {
unsigned int useroffset; /* Usercopy region offset */
unsigned int usersize; /* Usercopy region size */
+ struct rb_root user_hash_root;
+
struct kmem_cache_node *node[MAX_NUMNODES];
};
+struct hash_object {
+ int count;
+ depot_stack_handle_t trace_hash;
+ struct rb_node rb_node;
+};
#ifdef CONFIG_SYSFS
#define SLAB_SUPPORTS_SYSFS
void sysfs_slab_unlink(struct kmem_cache *);
diff --git a/mm/slub.c b/mm/slub.c
index 157527d..3ec02ff 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -337,6 +337,7 @@ static inline void stat(const struct kmem_cache *s, enum stat_item si)
*/
static struct workqueue_struct *flushwq;
+static struct kmem_cache *user_hash_cache;
/********************************************************************
* Core slab cache functions
*******************************************************************/
@@ -759,12 +760,152 @@ static void set_track_update(struct kmem_cache *s, void *object,
p->when = jiffies;
}
+static void store_user_hash(struct kmem_cache *s, void *object,
+ depot_stack_handle_t trace_hash, enum track_item alloc)
+{
+ struct rb_node *rb_parent;
+ unsigned int trace_hash_parent;
+ struct rb_node **link = &s->user_hash_root.rb_node;
+ struct hash_object *hash_parent = NULL;
+ struct hash_object *hash_object = NULL;
+ unsigned long flags;
+ int count;
+ int nid = slab_nid(virt_to_slab(object));
+ struct kmem_cache_node *n = get_node(s, nid);
+
+ spin_lock_irqsave(&n->list_lock, flags);
+ while (*link) {
+ rb_parent = *link;
+ hash_parent = rb_entry(rb_parent, struct hash_object, rb_node);
+ trace_hash_parent = hash_parent->trace_hash;
+ if (trace_hash < trace_hash_parent)
+ link = &hash_parent->rb_node.rb_left;
+ else if (trace_hash_parent < trace_hash)
+ link = &hash_parent->rb_node.rb_right;
+ else {
+ hash_object = rb_entry(*link, struct hash_object, rb_node);
+ count = (alloc == TRACK_ALLOC) ? 1 : -1;
+ hash_object->count += count;
+ if (!RB_EMPTY_ROOT(&s->user_hash_root)
+ && !hash_object->count) {
+ rb_erase(&hash_object->rb_node, &s->user_hash_root);
+ kmem_cache_free(user_hash_cache, hash_object);
+ }
+ spin_unlock_irqrestore(&n->list_lock, flags);
+ return;
+ }
+ }
+ spin_unlock_irqrestore(&n->list_lock, flags);
+ /*
+ * hash_object is the 1st node represent this trace_hash
+ * insert it to user_hash_root
+ */
+ hash_object = kmem_cache_alloc(user_hash_cache, GFP_KERNEL);
+ if (!hash_object)
+ return;
+ hash_object->trace_hash = trace_hash;
+ /* add the node to rb tree*/
+ spin_lock_irqsave(&n->list_lock, flags);
+ rb_link_node(&hash_object->rb_node, rb_parent, link);
+ rb_insert_color(&hash_object->rb_node, &s->user_hash_root);
+ spin_unlock_irqrestore(&n->list_lock, flags);
+ return;
+}
+
+static ssize_t backtrace_acc_print(struct file *file, char __user *buf, size_t count, loff_t *ppos)
+{
+ struct hash_object *object;
+ struct rb_node *rb;
+ unsigned long *entries;
+ unsigned int nr_entries;
+ char *kbuf;
+ int i, ret = 0;
+ unsigned long flags;
+ struct kmem_cache_node *n;
+ enum track_item alloc;
+ int node;
+ struct slab *slab;
+ struct kmem_cache *s = file_inode(file)->i_private;
+
+ count = min_t(size_t, count, PAGE_SIZE);
+ kbuf = kmalloc(count, GFP_KERNEL);
+ if (!kbuf)
+ return -ENOMEM;
+
+ /* iterate from node-0 */
+ node = *ppos;
+ if (node >= nr_node_ids)
+ return 0;
+
+ if ((n = get_node(s, node))) {
+ /* skip empty node */
+ while (!atomic_long_read(&n->nr_slabs)) {
+ if (++node >= nr_node_ids)
+ return 0;
+ n = get_node(s, node);
+ }
+
+ rb = file->private_data ? (struct rb_node *)file->private_data : rb_first(&s->user_hash_root);
+ /* current node finish, reset rb to next node's root */
+ if(!rb) {
+ ret += snprintf(kbuf + ret, count - ret, "\n");
+ copy_to_user(buf, kbuf, ret);
+ file->private_data = 0;
+ *ppos = ++node;
+ return ret;
+ }
+
+ spin_lock_irqsave(&n->list_lock, flags);
+ object = rb_entry(rb, struct hash_object, rb_node);
+ if (object) {
+ while (!object->trace_hash || object->count <= 0) {
+ rb = rb_next(rb);
+ object = rb ? rb_entry(rb, struct hash_object, rb_node) : NULL;
+ if (!object) {
+ spin_unlock_irqrestore(&n->list_lock, flags);
+ ret += snprintf(kbuf + ret, count - ret, "\n");
+ copy_to_user(buf, kbuf, ret);
+ file->private_data = 0;
+ *ppos = ++node;
+ kfree(kbuf);
+ return ret;
+ }
+ }
+ nr_entries = stack_depot_fetch(object->trace_hash, &entries);
+ ret += snprintf(kbuf + ret, count - ret, "count %d\n", object->count);
+ if (ret >= count)
+ goto err;
+ for (i = 0; i < nr_entries; i++) {
+ void *ptr = (void *)entries[i];
+ ret += snprintf(kbuf + ret, count - ret, " [<%p>] %pS\n", ptr, ptr);
+ if (ret >= count)
+ goto err;
+ }
+ }
+ file->private_data = (void *)rb_next(rb);
+ spin_unlock_irqrestore(&n->list_lock, flags);
+ *ppos = ++node;
+ if (copy_to_user(buf, kbuf, ret))
+ ret = -EFAULT;
+
+ kfree(kbuf);
+ return ret;
+err:
+ spin_unlock_irqrestore(&n->list_lock, flags);
+ kfree(kbuf);
+ return -ENOMEM;
+ }
+ return 0;
+}
+
static __always_inline void set_track(struct kmem_cache *s, void *object,
enum track_item alloc, unsigned long addr)
{
depot_stack_handle_t handle = set_track_prepare();
set_track_update(s, object, alloc, addr, handle);
+ if (strcmp(s->name, "user_hash_cache") != 0)
+ store_user_hash(s, object, handle, alloc);
}
static void init_tracking(struct kmem_cache *s, void *object)
@@ -4918,8 +5059,10 @@ int __kmem_cache_create(struct kmem_cache *s, slab_flags_t flags)
return err;
}
- if (s->flags & SLAB_STORE_USER)
+ if (s->flags & SLAB_STORE_USER) {
+ s->user_hash_root = RB_ROOT;
debugfs_slab_add(s);
+ }
return 0;
}
@@ -6236,6 +6379,10 @@ static int slab_debug_trace_release(struct inode *inode, struct file *file)
.release = slab_debug_trace_release,
};
+static const struct file_operations backtrace_accounting_operations = {
+ .read = backtrace_acc_print,
+};
+
static void debugfs_slab_add(struct kmem_cache *s)
{
struct dentry *slab_cache_dir;
@@ -6250,6 +6397,9 @@ static void debugfs_slab_add(struct kmem_cache *s)
debugfs_create_file("free_traces", 0400,
slab_cache_dir, s, &slab_debugfs_fops);
+
+ debugfs_create_file("backtrace_accounting", 0400, NULL, NULL,
+ &backtrace_accounting_operations);
}
void debugfs_slab_release(struct kmem_cache *s)
@@ -6261,6 +6411,9 @@ static int __init slab_debugfs_init(void)
{
struct kmem_cache *s;
+ user_hash_cache = kmem_cache_create("user_hash_cache",
+ sizeof(struct hash_object),
+ 0, 0, NULL);
slab_debugfs_root = debugfs_create_dir("slab", NULL);
list_for_each_entry(s, &slab_caches, list)
--
1.9.1
