When slub_debug alloc_calls_show is enabled we will try to track
location and user of slab object on each online node, kmem_cache_node
structure and cpu_cache/cpu_slub shouldn't be freed till there is the
last reference to sysfs file.
This fixes the following panic:
BUG: unable to handle kernel NULL pointer dereference at 0000000000000020
IP: list_locations+0x169/0x4e0
PGD 257304067 PUD 438456067 PMD 0
Oops: 0000 [#1] SMP
CPU: 3 PID: 973074 Comm: cat ve: 0 Not tainted
3.10.0-229.7.2.ovz.9.30-00007-japdoll-dirty #2 9.30
Hardware name: DEPO Computers To Be Filled By O.E.M./H67DE3, BIOS L1.60c
07/14/2011
task: ffff88042a5dc5b0 ti: ffff88037f8d8000 task.ti: ffff88037f8d8000
RIP: list_locations+0x169/0x4e0
Call Trace:
alloc_calls_show+0x1d/0x30
slab_attr_show+0x1b/0x30
sysfs_read_file+0x9a/0x1a0
vfs_read+0x9c/0x170
SyS_read+0x58/0xb0
system_call_fastpath+0x16/0x1b
Code: 5e 07 12 00 b9 00 04 00 00 3d 00 04 00 00 0f 4f c1 3d 00 04 00 00 89
45 b0 0f 84 c3 00 00 00 48 63 45 b0 49 8b 9c c4 f8 00 00 00 <48> 8b 43 20 48 85
c0 74 b6 48 89 df e8 46 37 44 00 48 8b 53 10
CR2: 0000000000000020
Separated __kmem_cache_release from __kmem_cache_shutdown which now
called on slab_kmem_cache_release (after the last reference to sysfs
file object has dropped).
Reintroduced locking in free_partial as sysfs file might access cache's
partial list after shutdowning - partial revert of the commit
69cb8e6b7c29 ("slub: free slabs without holding locks"). Zap
__remove_partial and use remove_partial (w/o underscores) as
free_partial now takes list_lock which s partial revert for commit
1e4dd9461fab ("slub: do not assert not having lock in removing freed
partial")
Signed-off-by: Dmitry Safonov <[email protected]>
Suggested-by: Vladimir Davydov <[email protected]>
Acked-by: Vladimir Davydov <[email protected]>
Cc: Christoph Lameter <[email protected]>
Cc: Pekka Enberg <[email protected]>
Cc: David Rientjes <[email protected]>
Cc: Joonsoo Kim <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
[ported from ms, resolved conflicts with commit 18bf854117c6 ("slab: use
get_node() and kmem_cache_node() functions") and commit bf0dea23a9c0
("mm/slab: use percpu allocator for cpu cache")
Signed-off-by: Dmitry Safonov <[email protected]>
---
mm/slab.c | 12 ++++++------
mm/slab.h | 1 +
mm/slab_common.c | 1 +
mm/slob.c | 4 ++++
mm/slub.c | 38 +++++++++++++++++---------------------
5 files changed, 29 insertions(+), 27 deletions(-)
diff --git a/mm/slab.c b/mm/slab.c
index 0c1c67c..3282316 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -2391,7 +2391,7 @@ __kmem_cache_create (struct kmem_cache *cachep, unsigned
long flags)
err = setup_cpu_cache(cachep, gfp);
if (err) {
- __kmem_cache_shutdown(cachep);
+ __kmem_cache_release(cachep);
return err;
}
@@ -2545,12 +2545,13 @@ int __kmem_cache_shrink(struct kmem_cache *cachep, bool
deactivate)
int __kmem_cache_shutdown(struct kmem_cache *cachep)
{
+ return __kmem_cache_shrink(cachep, false);
+}
+
+void __kmem_cache_release(struct kmem_cache *cachep)
+{
int i;
struct kmem_cache_node *n;
- int rc = __kmem_cache_shrink(cachep, false);
-
- if (rc)
- return rc;
for_each_online_cpu(i)
kfree(cachep->array[i]);
@@ -2564,7 +2565,6 @@ int __kmem_cache_shutdown(struct kmem_cache *cachep)
kfree(n);
}
}
- return 0;
}
/*
diff --git a/mm/slab.h b/mm/slab.h
index 5f6c6a2..57de63f 100644
--- a/mm/slab.h
+++ b/mm/slab.h
@@ -125,6 +125,7 @@ __kmem_cache_alias(const char *name, size_t size, size_t
align,
#define CACHE_CREATE_MASK (SLAB_CORE_FLAGS | SLAB_DEBUG_FLAGS |
SLAB_CACHE_FLAGS)
int __kmem_cache_shutdown(struct kmem_cache *);
+void __kmem_cache_release(struct kmem_cache *);
int __kmem_cache_shrink(struct kmem_cache *, bool);
void slab_kmem_cache_release(struct kmem_cache *);
diff --git a/mm/slab_common.c b/mm/slab_common.c
index 9bae922..18226a6 100644
--- a/mm/slab_common.c
+++ b/mm/slab_common.c
@@ -503,6 +503,7 @@ void memcg_destroy_kmem_caches(struct mem_cgroup *memcg)
void slab_kmem_cache_release(struct kmem_cache *s)
{
+ __kmem_cache_release(s);
destroy_memcg_params(s);
kfree(s->name);
kmem_cache_free(kmem_cache, s);
diff --git a/mm/slob.c b/mm/slob.c
index abe2693..d377c61 100644
--- a/mm/slob.c
+++ b/mm/slob.c
@@ -620,6 +620,10 @@ int __kmem_cache_shutdown(struct kmem_cache *c)
return 0;
}
+void __kmem_cache_release(struct kmem_cache *c)
+{
+}
+
int __kmem_cache_shrink(struct kmem_cache *d, bool deactivate)
{
return 0;
diff --git a/mm/slub.c b/mm/slub.c
index 7a4ad43..80c7b79 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -1525,18 +1525,12 @@ static inline void add_partial(struct kmem_cache_node
*n,
__add_partial(n, page, tail);
}
-static inline void
-__remove_partial(struct kmem_cache_node *n, struct page *page)
-{
- list_del(&page->lru);
- n->nr_partial--;
-}
-
static inline void remove_partial(struct kmem_cache_node *n,
struct page *page)
{
lockdep_assert_held(&n->list_lock);
- __remove_partial(n, page);
+ list_del(&page->lru);
+ n->nr_partial--;
}
/*
@@ -2938,6 +2932,12 @@ static void free_kmem_cache_nodes(struct kmem_cache *s)
}
}
+void __kmem_cache_release(struct kmem_cache *s)
+{
+ free_percpu(s->cpu_slab);
+ free_kmem_cache_nodes(s);
+}
+
static int init_kmem_cache_nodes(struct kmem_cache *s)
{
int node;
@@ -3198,28 +3198,31 @@ static void list_slab_objects(struct kmem_cache *s,
struct page *page,
/*
* Attempt to free all partial slabs on a node.
- * This is called from kmem_cache_close(). We must be the last thread
- * using the cache and therefore we do not need to lock anymore.
+ * This is called from __kmem_cache_shutdown(). We must take list_lock
+ * because sysfs file might still access partial list after the shutdowning.
*/
static void free_partial(struct kmem_cache *s, struct kmem_cache_node *n)
{
struct page *page, *h;
+ BUG_ON(irqs_disabled());
+ spin_lock_irq(&n->list_lock);
list_for_each_entry_safe(page, h, &n->partial, lru) {
if (!page->inuse) {
- __remove_partial(n, page);
+ remove_partial(n, page);
discard_slab(s, page);
} else {
list_slab_objects(s, page,
- "Objects remaining in %s on kmem_cache_close()");
+ "Objects remaining in %s on __kmem_cache_shutdown()");
}
}
+ spin_unlock_irq(&n->list_lock);
}
/*
* Release all resources used by a slab cache.
*/
-static inline int kmem_cache_close(struct kmem_cache *s)
+int __kmem_cache_shutdown(struct kmem_cache *s)
{
int node;
@@ -3232,16 +3235,9 @@ static inline int kmem_cache_close(struct kmem_cache *s)
if (n->nr_partial || slabs_node(s, node))
return 1;
}
- free_percpu(s->cpu_slab);
- free_kmem_cache_nodes(s);
return 0;
}
-int __kmem_cache_shutdown(struct kmem_cache *s)
-{
- return kmem_cache_close(s);
-}
-
/********************************************************************
* Kmalloc subsystem
*******************************************************************/
@@ -3850,7 +3846,7 @@ int __kmem_cache_create(struct kmem_cache *s, unsigned
long flags)
memcg_propagate_slab_attrs(s);
err = sysfs_slab_add(s);
if (err)
- kmem_cache_close(s);
+ __kmem_cache_release(s);
return err;
}
--
2.7.2
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