linux-kernel - [PATCH v4 0/3] Refactor __kmem_cache

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Message-ID: <20221112114602.1268989-1-liushixin2@huawei.com>
Date:   Sat, 12 Nov 2022 19:45:59 +0800
From:   Liu Shixin <liushixin2@...wei.com>
To:     Christoph Lameter <cl@...ux.com>,
        Pekka Enberg <penberg@...nel.org>,
        "David Rientjes" <rientjes@...gle.com>,
        Joonsoo Kim <iamjoonsoo.kim@....com>,
        "Andrew Morton" <akpm@...ux-foundation.org>,
        Vlastimil Babka <vbabka@...e.cz>,
        "Roman Gushchin" <roman.gushchin@...ux.dev>,
        Hyeonggon Yoo <42.hyeyoo@...il.com>
CC:     <linux-mm@...ck.org>, <linux-kernel@...r.kernel.org>,
        Liu Shixin <liushixin2@...wei.com>
Subject: [PATCH v4 0/3] Refactor __kmem_cache_create() and fix memory leak

I found a memory leak of kobj->name in sysfs_slab_add() which is introduced
by 80da026a8e5d ("mm/slub: fix slab double-free in case of duplicate sysfs filename").
Following the rules stated in the comment for kobject_init_and_add():

 If this function returns an error, kobject_put() must be called to
 properly clean up the memory associated with the object.

We should use kobject_put() to free kobject.

But we can't simply add kobject_put() since it will free kmem_cache too.
If we use kobject_put(), we need to skip other release functions.

In this series, We refactor the code to separate sysfs_slab_add() and
debugfs_slab_add() from __kmem_cache_create(), and then use kobject_put()
to free kobject in sysfs_slab_add(). This can fix the memory leak of
kobject->name.

v1->v2: Fix build error reported by kernel test robot <lkp@...el.com>.
v2->v3: Don't free kmem_cache that create early.
v3->v4: Fix error in kfree_const of kobject's name.

Liu Shixin (3):
  mm/slab_common: Move cache_name to create_cache()
  mm/slub: Refactor __kmem_cache_create()
  mm/slub: Fix memory leak of kobj->name in sysfs_slab_add()

 include/linux/slub_def.h | 11 +++++++
 mm/slab_common.c         | 44 +++++++++++++++-------------
 mm/slub.c                | 63 +++++++++++++++-------------------------
 3 files changed, 58 insertions(+), 60 deletions(-)

--
2.25.1