The patch titled
Subject: mm: slab: free kmem_cache_node after destroy sysfs file
has been removed from the -mm tree. Its filename was
mm-slab-free-kmem_cache_node-after-destroy-sysfs-file.patch
This patch was dropped because it was merged into mainline or a subsystem tree
------------------------------------------------------
From: Dmitry Safonov <dsafonov@xxxxxxxxxxxxx>
Subject: 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.
Fixes the following panic:
[43963.463055] BUG: unable to handle kernel
[43963.463090] NULL pointer dereference at 0000000000000020
[43963.463146] IP: [<ffffffff811c6959>] list_locations+0x169/0x4e0
[43963.463185] PGD 257304067 PUD 438456067 PMD 0
[43963.463220] Oops: 0000 [#1] SMP
[43963.463850] 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
[43963.463913] Hardware name: DEPO Computers To Be Filled By O.E.M./H67DE3, BIOS L1.60c 07/14/2011
[43963.463976] task: ffff88042a5dc5b0 ti: ffff88037f8d8000 task.ti: ffff88037f8d8000
[43963.464036] RIP: 0010:[<ffffffff811c6959>] [<ffffffff811c6959>] list_locations+0x169/0x4e0
[43963.464725] Call Trace:
[43963.464756] [<ffffffff811c6d1d>] alloc_calls_show+0x1d/0x30
[43963.464793] [<ffffffff811c15ab>] slab_attr_show+0x1b/0x30
[43963.464829] [<ffffffff8125d27a>] sysfs_read_file+0x9a/0x1a0
[43963.464865] [<ffffffff811e3c6c>] vfs_read+0x9c/0x170
[43963.464900] [<ffffffff811e4798>] SyS_read+0x58/0xb0
[43963.464936] [<ffffffff81612d49>] system_call_fastpath+0x16/0x1b
[43963.464970] 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
[43963.465119] RIP [<ffffffff811c6959>] list_locations+0x169/0x4e0
[43963.465155] RSP <ffff88037f8dbe28>
[43963.465185] 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 - partiall revert of the commit
69cb8e6b7c2982 ("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 1e4dd9461fabfb
("slub: do not assert not having lock in removing freed partial")
Signed-off-by: Dmitry Safonov <dsafonov@xxxxxxxxxxxxx>
Suggested-by: Vladimir Davydov <vdavydov@xxxxxxxxxxxxx>
Acked-by: Vladimir Davydov <vdavydov@xxxxxxxxxxxxx>
Cc: Christoph Lameter <cl@xxxxxxxxx>
Cc: Pekka Enberg <penberg@xxxxxxxxxx>
Cc: David Rientjes <rientjes@xxxxxxxxxx>
Cc: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
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 -puN mm/slab.c~mm-slab-free-kmem_cache_node-after-destroy-sysfs-file mm/slab.c
--- a/mm/slab.c~mm-slab-free-kmem_cache_node-after-destroy-sysfs-file
+++ a/mm/slab.c
@@ -2275,7 +2275,7 @@ __kmem_cache_create (struct kmem_cache *
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_cach
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_ca
kfree(n);
cachep->node[i] = NULL;
}
- return 0;
}
/*
diff -puN mm/slab.h~mm-slab-free-kmem_cache_node-after-destroy-sysfs-file mm/slab.h
--- a/mm/slab.h~mm-slab-free-kmem_cache_node-after-destroy-sysfs-file
+++ a/mm/slab.h
@@ -140,6 +140,7 @@ static inline unsigned long kmem_cache_f
#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 -puN mm/slab_common.c~mm-slab-free-kmem_cache_node-after-destroy-sysfs-file mm/slab_common.c
--- a/mm/slab_common.c~mm-slab-free-kmem_cache_node-after-destroy-sysfs-file
+++ a/mm/slab_common.c
@@ -693,6 +693,7 @@ static inline int shutdown_memcg_caches(
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 -puN mm/slob.c~mm-slab-free-kmem_cache_node-after-destroy-sysfs-file mm/slob.c
--- a/mm/slob.c~mm-slab-free-kmem_cache_node-after-destroy-sysfs-file
+++ a/mm/slob.c
@@ -630,6 +630,10 @@ int __kmem_cache_shutdown(struct kmem_ca
return 0;
}
+void __kmem_cache_release(struct kmem_cache *c)
+{
+}
+
int __kmem_cache_shrink(struct kmem_cache *d, bool deactivate)
{
return 0;
diff -puN mm/slub.c~mm-slab-free-kmem_cache_node-after-destroy-sysfs-file mm/slub.c
--- a/mm/slub.c~mm-slab-free-kmem_cache_node-after-destroy-sysfs-file
+++ a/mm/slub.c
@@ -1592,18 +1592,12 @@ static inline void add_partial(struct km
__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
}
}
+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 kme
/*
* 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(struc
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_cach
memcg_propagate_slab_attrs(s);
err = sysfs_slab_add(s);
if (err)
- kmem_cache_close(s);
+ __kmem_cache_release(s);
return err;
}
_
Patches currently in -mm which might be from dsafonov@xxxxxxxxxxxxx are
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