This adds a leak decoder callback so that kmem_cache_destroy()
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.
Signed-off-by: Liu Bo <bo.li.liu@xxxxxxxxxx>
---
The idea is from Zach Brown <zab@xxxxxxxxx>.
fs/btrfs/extent_io.c | 24 ++++++++++++++++++++++++
fs/btrfs/extent_map.c | 12 ++++++++++++
include/linux/slab.h | 1 +
include/linux/slab_def.h | 1 +
include/linux/slub_def.h | 1 +
mm/slab_common.c | 1 +
mm/slub.c | 5 +++++
7 files changed, 45 insertions(+), 0 deletions(-)
diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index bcc8dff..4954f3d 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",
@@ -71,11 +91,15 @@ int __init extent_io_init(void)
if (!extent_state_cache)
return -ENOMEM;
+ extent_state_cache->decoder = extent_state_leak_decoder;
+
extent_buffer_cache = kmem_cache_create("btrfs_extent_buffer",
sizeof(struct extent_buffer), 0,
SLAB_RECLAIM_ACCOUNT | SLAB_MEM_SPREAD, NULL);
if (!extent_buffer_cache)
goto free_state_cache;
+
+ extent_buffer_cache->decoder = extent_buffer_leak_decoder;
return 0;
free_state_cache:
diff --git a/fs/btrfs/extent_map.c b/fs/btrfs/extent_map.c
index 80370d6..d598a8d 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",
@@ -23,6 +33,8 @@ int __init extent_map_init(void)
SLAB_RECLAIM_ACCOUNT | SLAB_MEM_SPREAD, NULL);
if (!extent_map_cache)
return -ENOMEM;
+
+ extent_map_cache->decoder = extent_map_leak_decoder;
return 0;
}
diff --git a/include/linux/slab.h b/include/linux/slab.h
index 5d168d7..89a9efd 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
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..39a0fb2 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);
diff --git a/mm/slub.c b/mm/slub.c
index ba2ca53..0496a2b 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);
@@ -3787,6 +3789,9 @@ static int slab_unmergeable(struct kmem_cache *s)
if (s->ctor)
return 1;
+ if (s->decoder)
+ return 1;
+
/*
* We may have set a slab to be unmergeable during bootstrap.
*/
--
1.7.7.6
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