The patch titled
Subject: slab: update_memcg_params: explicitly check that old array != NULL
has been removed from the -mm tree. Its filename was
slab-embed-memcg_cache_params-to-kmem_cache-fix.patch
This patch was dropped because it was folded into slab-embed-memcg_cache_params-to-kmem_cache.patch
------------------------------------------------------
From: Vladimir Davydov <vdavydov@xxxxxxxxxxxxx>
Subject: slab: update_memcg_params: explicitly check that old array != NULL
mm/slab_common.c:166 update_memcg_params() warn: variable dereferenced before check 'old' (see line 162)
This warning is false-positive, because @old equals NULL iff
@memcg_nr_cache_ids equals 0. Moreover, this function had been acting in
exactly the same fashion before it was reworked by the culprit. Anyways,
let's add an explicit check if @old is not NULL before passing it to
@memcpy() to make static analysis tools happy.
Signed-off-by: Vladimir Davydov <vdavydov@xxxxxxxxxxxxx>
Reported-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/slab_common.c | 9 +++++----
1 file changed, 5 insertions(+), 4 deletions(-)
diff -puN mm/slab_common.c~slab-embed-memcg_cache_params-to-kmem_cache-fix mm/slab_common.c
--- a/mm/slab_common.c~slab-embed-memcg_cache_params-to-kmem_cache-fix
+++ a/mm/slab_common.c
@@ -152,15 +152,16 @@ static int update_memcg_params(struct km
if (!is_root_cache(s))
return 0;
- old = rcu_dereference_protected(s->memcg_params.memcg_caches,
- lockdep_is_held(&slab_mutex));
new = kzalloc(sizeof(struct memcg_cache_array) +
new_array_size * sizeof(void *), GFP_KERNEL);
if (!new)
return -ENOMEM;
- memcpy(new->entries, old->entries,
- memcg_nr_cache_ids * sizeof(void *));
+ old = rcu_dereference_protected(s->memcg_params.memcg_caches,
+ lockdep_is_held(&slab_mutex));
+ if (old)
+ memcpy(new->entries, old->entries,
+ memcg_nr_cache_ids * sizeof(void *));
rcu_assign_pointer(s->memcg_params.memcg_caches, new);
if (old)
_
Patches currently in -mm which might be from vdavydov@xxxxxxxxxxxxx are
origin.patch
list_lru-introduce-list_lru_shrink_countwalk.patch
fs-consolidate-nrfree_cached_objects-args-in-shrink_control.patch
vmscan-per-memory-cgroup-slab-shrinkers.patch
memcg-rename-some-cache-id-related-variables.patch
memcg-add-rwsem-to-synchronize-against-memcg_caches-arrays-relocation.patch
list_lru-get-rid-of-active_nodes.patch
list_lru-organize-all-list_lrus-to-list.patch
list_lru-introduce-per-memcg-lists.patch
fs-make-shrinker-memcg-aware.patch
fs-shrinker-always-scan-at-least-one-object-of-each-type.patch
slab-embed-memcg_cache_params-to-kmem_cache.patch
slab-link-memcg-caches-of-the-same-kind-into-a-list.patch
slab-link-memcg-caches-of-the-same-kind-into-a-list-fix.patch
cgroup-release-css-id-after-css_free.patch
slab-use-css-id-for-naming-per-memcg-caches.patch
memcg-free-memcg_caches-slot-on-css-offline.patch
list_lru-add-helpers-to-isolate-items.patch
memcg-reparent-list_lrus-and-free-kmemcg_id-on-css-offline.patch
slub-never-fail-to-shrink-cache.patch
slub-never-fail-to-shrink-cache-init-discard-list-after-freeing-slabs.patch
slub-fix-kmem_cache_shrink-return-value.patch
slub-make-dead-caches-discard-free-slabs-immediately.patch
memcg-cleanup-static-keys-decrement.patch
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