The patch titled
Subject: slab: update_memcg_params: explicitly check that old array != NULL
has been added to the -mm tree. Its filename is
slab-embed-memcg_cache_params-to-kmem_cache-fix.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/slab-embed-memcg_cache_params-to-kmem_cache-fix.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/slab-embed-memcg_cache_params-to-kmem_cache-fix.patch
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*** Remember to use Documentation/SubmitChecklist when testing your code ***
The -mm tree is included into linux-next and is updated
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------------------------------------------------------
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
mm-vmscan-fix-highidx-argument-type.patch
memcg-zap-__memcg_chargeuncharge_slab.patch
memcg-zap-memcg_name-argument-of-memcg_create_kmem_cache.patch
memcg-zap-memcg_slab_caches-and-memcg_slab_mutex.patch
swap-remove-unused-mem_cgroup_uncharge_swapcache-declaration.patch
mm-memcontrol-track-move_lock-state-internally.patch
mm-vmscan-wake-up-all-pfmemalloc-throttled-processes-at-once.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
vmscan-force-scan-offline-memory-cgroups.patch
vmscan-force-scan-offline-memory-cgroups-fix.patch
mm-page_counter-pull-1-handling-out-of-page_counter_memparse.patch
mm-memcontrol-default-hierarchy-interface-for-memory.patch
mm-memcontrol-fold-move_anon-and-move_file.patch
mm-memcontrol-fold-move_anon-and-move_file-fix.patch
mm-memcontrol-simplify-soft-limit-tree-init-code.patch
mm-memcontrol-consolidate-memory-controller-initialization.patch
mm-memcontrol-consolidate-swap-controller-code.patch
fs-shrinker-always-scan-at-least-one-object-of-each-type.patch
fs-shrinker-always-scan-at-least-one-object-of-each-type-fix.patch
mm-vmscan-fix-the-page-state-calculation-in-too_many_isolated.patch
mm-vmscan-fix-the-page-state-calculation-in-too_many_isolated-fix.patch
slab-embed-memcg_cache_params-to-kmem_cache.patch
slab-embed-memcg_cache_params-to-kmem_cache-fix.patch
slab-link-memcg-caches-of-the-same-kind-into-a-list.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
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