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authorDmitry Safonov <dsafonov@virtuozzo.com>2016-02-17 13:11:37 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2016-02-18 16:23:24 -0800
commit52b4b950b50740bff507a62907e86710743c22e7 (patch)
tree16ec207435a99a4bc95482906acd8468fd322b82
parent1ac0b6dec656f3f78d1c3dd216fad84cb4d0a01e (diff)
mm: slab: free kmem_cache_node after destroy sysfs file
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 <dsafonov@virtuozzo.com> Suggested-by: Vladimir Davydov <vdavydov@virtuozzo.com> Acked-by: Vladimir Davydov <vdavydov@virtuozzo.com> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--mm/slab.c12
-rw-r--r--mm/slab.h1
-rw-r--r--mm/slab_common.c1
-rw-r--r--mm/slob.c4
-rw-r--r--mm/slub.c38
5 files changed, 29 insertions, 27 deletions
diff --git a/mm/slab.c b/mm/slab.c
index 6ecc697a8bc4..621fbcb35a36 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -2275,7 +2275,7 @@ __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;
}
@@ -2414,12 +2414,13 @@ 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;
free_percpu(cachep->cpu_cache);
@@ -2430,7 +2431,6 @@ int __kmem_cache_shutdown(struct kmem_cache *cachep)
kfree(n);
cachep->node[i] = NULL;
}
- return 0;
}
/*
diff --git a/mm/slab.h b/mm/slab.h
index 834ad240c0bb..2eedacea439d 100644
--- a/mm/slab.h
+++ b/mm/slab.h
@@ -140,6 +140,7 @@ static inline unsigned long kmem_cache_flags(unsigned long object_size,
#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 b50aef01ccf7..065b7bdabdc3 100644
--- a/mm/slab_common.c
+++ b/mm/slab_common.c
@@ -693,6 +693,7 @@ static inline int shutdown_memcg_caches(struct kmem_cache *s,
void slab_kmem_cache_release(struct kmem_cache *s)
{
+ __kmem_cache_release(s);
destroy_memcg_params(s);
kfree_const(s->name);
kmem_cache_free(kmem_cache, s);
diff --git a/mm/slob.c b/mm/slob.c
index 17e8f8cc7c53..5ec158054ffe 100644
--- a/mm/slob.c
+++ b/mm/slob.c
@@ -630,6 +630,10 @@ 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 2e1355ac056b..d8fbd4a6ed59 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -1592,18 +1592,12 @@ 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--;
}
/*
@@ -3184,6 +3178,12 @@ 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;
@@ -3443,28 +3443,31 @@ 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;
struct kmem_cache_node *n;
@@ -3476,16 +3479,9 @@ 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
*******************************************************************/
@@ -3980,7 +3976,7 @@ 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;
}