This adds a leak decoder callback so that slab destruction
can use to generate debugging output for the allocated objects.
Callers like btrfs are using their own leak tracking which will
manage allocated objects in a list(or something else), this does
indeed the same thing as what slab does. So adding a callback
for leak tracking can avoid this as well as runtime overhead.
(The idea is from Zach Brown <zab@xxxxxxxxx>.)
Signed-off-by: Liu Bo <bo.li.liu@xxxxxxxxxx>
---
v2: add a wrapper API for slab destruction to make decoder only
work in particular path.
fs/btrfs/extent_io.c | 26 ++++++++++++++++++++++++--
fs/btrfs/extent_map.c | 13 ++++++++++++-
include/linux/slab.h | 2 ++
include/linux/slab_def.h | 1 +
include/linux/slub_def.h | 1 +
mm/slab_common.c | 17 ++++++++++++++++-
mm/slub.c | 2 ++
7 files changed, 58 insertions(+), 4 deletions(-)
diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index bcc8dff..355c7fc 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -63,6 +63,26 @@ tree_fs_info(struct extent_io_tree *tree)
return btrfs_sb(tree->mapping->host->i_sb);
}
+static void extent_state_leak_decoder(void *object)
+{
+ struct extent_state *state = object;
+
+ printk(KERN_ERR "btrfs state leak: start %llu end %llu "
+ "state %lu in tree %p refs %d\n",
+ (unsigned long long)state->start,
+ (unsigned long long)state->end,
+ state->state, state->tree, atomic_read(&state->refs));
+}
+
+static void extent_buffer_leak_decoder(void *object)
+{
+ struct extent_buffer *eb = object;
+
+ printk(KERN_ERR "btrfs buffer leak start %llu len %lu "
+ "refs %d\n", (unsigned long long)eb->start,
+ eb->len, atomic_read(&eb->refs));
+}
+
int __init extent_io_init(void)
{
extent_state_cache = kmem_cache_create("btrfs_extent_state",
@@ -115,9 +135,11 @@ void extent_io_exit(void)
*/
rcu_barrier();
if (extent_state_cache)
- kmem_cache_destroy(extent_state_cache);
+ kmem_cache_destroy_decoder(extent_state_cache,
+ extent_state_leak_decoder);
if (extent_buffer_cache)
- kmem_cache_destroy(extent_buffer_cache);
+ kmem_cache_destroy_decoder(extent_buffer_cache,
+ extent_buffer_leak_decoder);
}
void extent_io_tree_init(struct extent_io_tree *tree,
diff --git a/fs/btrfs/extent_map.c b/fs/btrfs/extent_map.c
index f359e4c..bccba3d 100644
--- a/fs/btrfs/extent_map.c
+++ b/fs/btrfs/extent_map.c
@@ -16,6 +16,16 @@ static LIST_HEAD(emaps);
static DEFINE_SPINLOCK(map_leak_lock);
#endif
+static void extent_map_leak_decoder(void *object)
+{
+ struct extent_map *em = object;
+
+ printk(KERN_ERR "btrfs ext map leak: start %llu len %llu block %llu "
+ "flags %lu refs %d in tree %d compress %d\n",
+ em->start, em->len, em->block_start, em->flags,
+ atomic_read(&em->refs), em->in_tree, (int)em->compress_type);
+}
+
int __init extent_map_init(void)
{
extent_map_cache = kmem_cache_create("btrfs_extent_map",
@@ -39,7 +49,8 @@ void extent_map_exit(void)
}
if (extent_map_cache)
- kmem_cache_destroy(extent_map_cache);
+ kmem_cache_destroy_decoder(extent_map_cache,
+ extent_map_leak_decoder);
}
/**
diff --git a/include/linux/slab.h b/include/linux/slab.h
index 5d168d7..5c6a8d8 100644
--- a/include/linux/slab.h
+++ b/include/linux/slab.h
@@ -114,6 +114,7 @@ struct kmem_cache {
const char *name; /* Slab name for sysfs */
int refcount; /* Use counter */
void (*ctor)(void *); /* Called on object slot creation */
+ void (*decoder)(void *);/* Called on object slot leak detection */
struct list_head list; /* List of all slab caches on the system */
};
#endif
@@ -132,6 +133,7 @@ struct kmem_cache *
kmem_cache_create_memcg(struct mem_cgroup *, const char *, size_t, size_t,
unsigned long, void (*)(void *), struct kmem_cache *);
void kmem_cache_destroy(struct kmem_cache *);
+void kmem_cache_destroy_decoder(struct kmem_cache *, void (*)(void *));
int kmem_cache_shrink(struct kmem_cache *);
void kmem_cache_free(struct kmem_cache *, void *);
diff --git a/include/linux/slab_def.h b/include/linux/slab_def.h
index 8bb6e0e..7ca8309 100644
--- a/include/linux/slab_def.h
+++ b/include/linux/slab_def.h
@@ -48,6 +48,7 @@ struct kmem_cache {
/* constructor func */
void (*ctor)(void *obj);
+ void (*decoder)(void *obj);
/* 4) cache creation/removal */
const char *name;
diff --git a/include/linux/slub_def.h b/include/linux/slub_def.h
index 9db4825..fc18af7 100644
--- a/include/linux/slub_def.h
+++ b/include/linux/slub_def.h
@@ -93,6 +93,7 @@ struct kmem_cache {
gfp_t allocflags; /* gfp flags to use on each alloc */
int refcount; /* Refcount for slab cache destroy */
void (*ctor)(void *);
+ void (*decoder)(void *);
int inuse; /* Offset to metadata */
int align; /* Alignment */
int reserved; /* Reserved bytes at the end of slabs */
diff --git a/mm/slab_common.c b/mm/slab_common.c
index 3f3cd97..8c19bfd 100644
--- a/mm/slab_common.c
+++ b/mm/slab_common.c
@@ -193,6 +193,7 @@ kmem_cache_create_memcg(struct mem_cgroup *memcg, const char *name, size_t size,
s->object_size = s->size = size;
s->align = calculate_alignment(flags, align, size);
s->ctor = ctor;
+ s->decoder = NULL;
if (memcg_register_cache(memcg, s, parent_cache)) {
kmem_cache_free(kmem_cache, s);
@@ -248,7 +249,7 @@ kmem_cache_create(const char *name, size_t size, size_t align,
}
EXPORT_SYMBOL(kmem_cache_create);
-void kmem_cache_destroy(struct kmem_cache *s)
+static void __kmem_cache_destroy(struct kmem_cache *s, void (*decoder)(void *))
{
/* Destroy all the children caches if we aren't a memcg cache */
kmem_cache_destroy_memcg_children(s);
@@ -259,6 +260,9 @@ void kmem_cache_destroy(struct kmem_cache *s)
if (!s->refcount) {
list_del(&s->list);
+ if (unlikely(decoder))
+ s->decoder = decoder;
+
if (!__kmem_cache_shutdown(s)) {
mutex_unlock(&slab_mutex);
if (s->flags & SLAB_DESTROY_BY_RCU)
@@ -279,8 +283,19 @@ void kmem_cache_destroy(struct kmem_cache *s)
}
put_online_cpus();
}
+
+void kmem_cache_destroy(struct kmem_cache *s)
+{
+ return __kmem_cache_destroy(s, NULL);
+}
EXPORT_SYMBOL(kmem_cache_destroy);
+void kmem_cache_destroy_decoder(struct kmem_cache *s, void (*decoder)(void *))
+{
+ return __kmem_cache_destroy(s, decoder);
+}
+EXPORT_SYMBOL(kmem_cache_destroy_decoder);
+
int slab_is_available(void)
{
return slab_state >= UP;
diff --git a/mm/slub.c b/mm/slub.c
index ba2ca53..34b3b75 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -3098,6 +3098,8 @@ static void list_slab_objects(struct kmem_cache *s, struct page *page,
for_each_object(p, s, addr, page->objects) {
if (!test_bit(slab_index(p, s, addr), map)) {
+ if (unlikely(s->decoder))
+ s->decoder(p);
printk(KERN_ERR "INFO: Object 0x%p @offset=%tu\n",
p, p - addr);
print_tracking(s, p);
--
1.7.7.6
--
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