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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
69cb8e6b7c ("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
1e4dd9461f ("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>
This commit is contained in:
Dmitry Safonov 2016-02-17 13:11:37 -08:00 committed by Linus Torvalds
parent 1ac0b6dec6
commit 52b4b950b5
5 changed files with 29 additions and 27 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

12
mm/slab.c
View File

@ -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;
}
@ -2413,13 +2413,14 @@ 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;
}
/*

1
mm/slab.h
View File

@ -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 *);

1
mm/slab_common.c
View File

@ -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);

4
mm/slob.c
View File

@ -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;

38
mm/slub.c
View File

@ -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;
}