On 2/28/24 15:34, Vlastimil Babka wrote:
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On 2/28/24 04:04, Xiaolei Wang wrote:
For earlier kmem cache creation, slab_sysfs_init() has not been called.
Consequently, kmem_cache_destroy() cannot utilize kobj_type::release to
release the kmem_cache structure. Therefore, tweak kmem_cache_release()
to use slab_kmem_cache_release() for releasing kmem_cache when slab_state
isn't FULL. This will fixes the memory leaks like following:
So do I understand correctly the leak happens when a cache is destroyed
while slab_state < FULL? Do we ever destroy a cache that early?
Yes, like some test programs, test_meminit_init() or
arm_v7s_alloc_pgtable(),
destroy will cause leaks after use, and when slab_state < FULL,
there are many places to create cache, which itself also has the risk of
leaks
thanks
xiaolei
unreferenced object 0xffff0000c2d87080 (size 128):
comm "swapper/0", pid 1, jiffies 4294893428
hex dump (first 32 bytes):
00 00 00 00 ad 4e ad de ff ff ff ff 6b 6b 6b 6b .....N......kkkk
ff ff ff ff ff ff ff ff b8 ab 48 89 00 80 ff ff.....H.....
backtrace (crc 8819d0f6):
[<ffff80008317a298>] kmemleak_alloc+0xb0/0xc4
[<ffff8000807e553c>] kmem_cache_alloc_node+0x288/0x3a8
[<ffff8000807e95f0>] __kmem_cache_create+0x1e4/0x64c
[<ffff8000807216bc>] kmem_cache_create_usercopy+0x1c4/0x2cc
[<ffff8000807217e0>] kmem_cache_create+0x1c/0x28
[<ffff8000819f6278>] arm_v7s_alloc_pgtable+0x1c0/0x6d4
[<ffff8000819f53a0>] alloc_io_pgtable_ops+0xe8/0x2d0
[<ffff800084b2d2c4>] arm_v7s_do_selftests+0xe0/0x73c
[<ffff800080016b68>] do_one_initcall+0x11c/0x7ac
[<ffff800084a71ddc>] kernel_init_freeable+0x53c/0xbb8
[<ffff8000831728d8>] kernel_init+0x24/0x144
[<ffff800080018e98>] ret_from_fork+0x10/0x20
Signed-off-by: Xiaolei Wang <xiaolei.wang@xxxxxxxxxxxxx>
---
mm/slab_common.c | 8 ++++++--
mm/slub.c | 6 ++----
2 files changed, 8 insertions(+), 6 deletions(-)
diff --git a/mm/slab_common.c b/mm/slab_common.c
index 238293b1dbe1..b6b35bcdd196 100644
--- a/mm/slab_common.c
+++ b/mm/slab_common.c
@@ -404,8 +404,12 @@ EXPORT_SYMBOL(kmem_cache_create);
*/
static void kmem_cache_release(struct kmem_cache *s)
{
- sysfs_slab_unlink(s);
- sysfs_slab_release(s);
+ if (slab_state >= FULL) {
+ sysfs_slab_unlink(s);
+ sysfs_slab_release(s);
+ } else {
+ slab_kmem_cache_release(s);
+ }
}
#else
static void kmem_cache_release(struct kmem_cache *s)
diff --git a/mm/slub.c b/mm/slub.c
index 2ef88bbf56a3..9ba59d064b6d 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -6792,14 +6792,12 @@ static int sysfs_slab_add(struct kmem_cache *s)
void sysfs_slab_unlink(struct kmem_cache *s)
{
- if (slab_state >= FULL)
- kobject_del(&s->kobj);
+ kobject_del(&s->kobj);
}
void sysfs_slab_release(struct kmem_cache *s)
{
- if (slab_state >= FULL)
- kobject_put(&s->kobj);
+ kobject_put(&s->kobj);
}
/*
