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author | Linus Torvalds <torvalds@linux-foundation.org> | 2022-09-01 19:14:56 +0300 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2022-09-01 19:14:56 +0300 |
commit | d330076e1d4b0cbaec477e1214f6f8df27da2bb8 (patch) | |
tree | f13147b38a934b5af5417e6b01b13db6d5dcad50 | |
parent | 2880e1a175b9f31798f9d9482ee49187f61b5539 (diff) | |
parent | 0495e337b7039191dfce6e03f5f830454b1fae6b (diff) | |
download | linux-d330076e1d4b0cbaec477e1214f6f8df27da2bb8.tar.xz |
Merge tag 'slab-for-6.0-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/vbabka/slab
Pull slab fix from Vlastimil Babka:
- A fix from Waiman Long to avoid a theoretical deadlock reported by
lockdep.
* tag 'slab-for-6.0-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/vbabka/slab:
mm/slab_common: Deleting kobject in kmem_cache_destroy() without holding slab_mutex/cpu_hotplug_lock
-rw-r--r-- | mm/slab_common.c | 45 |
1 files changed, 29 insertions, 16 deletions
diff --git a/mm/slab_common.c b/mm/slab_common.c index 17996649cfe3..07b948288f84 100644 --- a/mm/slab_common.c +++ b/mm/slab_common.c @@ -392,6 +392,28 @@ kmem_cache_create(const char *name, unsigned int size, unsigned int align, } EXPORT_SYMBOL(kmem_cache_create); +#ifdef SLAB_SUPPORTS_SYSFS +/* + * For a given kmem_cache, kmem_cache_destroy() should only be called + * once or there will be a use-after-free problem. The actual deletion + * and release of the kobject does not need slab_mutex or cpu_hotplug_lock + * protection. So they are now done without holding those locks. + * + * Note that there will be a slight delay in the deletion of sysfs files + * if kmem_cache_release() is called indrectly from a work function. + */ +static void kmem_cache_release(struct kmem_cache *s) +{ + sysfs_slab_unlink(s); + sysfs_slab_release(s); +} +#else +static void kmem_cache_release(struct kmem_cache *s) +{ + slab_kmem_cache_release(s); +} +#endif + static void slab_caches_to_rcu_destroy_workfn(struct work_struct *work) { LIST_HEAD(to_destroy); @@ -418,11 +440,7 @@ static void slab_caches_to_rcu_destroy_workfn(struct work_struct *work) list_for_each_entry_safe(s, s2, &to_destroy, list) { debugfs_slab_release(s); kfence_shutdown_cache(s); -#ifdef SLAB_SUPPORTS_SYSFS - sysfs_slab_release(s); -#else - slab_kmem_cache_release(s); -#endif + kmem_cache_release(s); } } @@ -437,20 +455,11 @@ static int shutdown_cache(struct kmem_cache *s) list_del(&s->list); if (s->flags & SLAB_TYPESAFE_BY_RCU) { -#ifdef SLAB_SUPPORTS_SYSFS - sysfs_slab_unlink(s); -#endif list_add_tail(&s->list, &slab_caches_to_rcu_destroy); schedule_work(&slab_caches_to_rcu_destroy_work); } else { kfence_shutdown_cache(s); debugfs_slab_release(s); -#ifdef SLAB_SUPPORTS_SYSFS - sysfs_slab_unlink(s); - sysfs_slab_release(s); -#else - slab_kmem_cache_release(s); -#endif } return 0; @@ -465,14 +474,16 @@ void slab_kmem_cache_release(struct kmem_cache *s) void kmem_cache_destroy(struct kmem_cache *s) { + int refcnt; + if (unlikely(!s) || !kasan_check_byte(s)) return; cpus_read_lock(); mutex_lock(&slab_mutex); - s->refcount--; - if (s->refcount) + refcnt = --s->refcount; + if (refcnt) goto out_unlock; WARN(shutdown_cache(s), @@ -481,6 +492,8 @@ void kmem_cache_destroy(struct kmem_cache *s) out_unlock: mutex_unlock(&slab_mutex); cpus_read_unlock(); + if (!refcnt && !(s->flags & SLAB_TYPESAFE_BY_RCU)) + kmem_cache_release(s); } EXPORT_SYMBOL(kmem_cache_destroy); |