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From: Andrew Morton <akpm@linux-foundation.org>
To: akpm@linux-foundation.org, cl@linux.com, guro@fb.com,
	iamjoonsoo.kim@lge.com, linux-mm@kvack.org,
	mm-commits@vger.kernel.org, penberg@kernel.org,
	rientjes@google.com, shakeelb@google.com,
	songmuchun@bytedance.com, stable@vger.kernel.org,
	torvalds@linux-foundation.org, vbabka@suse.cz
Subject: [patch 07/15] mm: memcg/slab: fix memory leak at non-root kmem_cache destroy
Date: Thu, 23 Jul 2020 21:15:27 -0700
Message-ID: <20200724041527.cGFVoVytc%akpm@linux-foundation.org> (raw)
In-Reply-To: <20200723211432.b31831a0df3bc2cbdae31b40@linux-foundation.org>

From: Muchun Song <songmuchun@bytedance.com>
Subject: mm: memcg/slab: fix memory leak at non-root kmem_cache destroy

If the kmem_cache refcount is greater than one, we should not mark the
root kmem_cache as dying.  If we mark the root kmem_cache dying
incorrectly, the non-root kmem_cache can never be destroyed.  It resulted
in memory leak when memcg was destroyed.  We can use the following steps
to reproduce.

  1) Use kmem_cache_create() to create a new kmem_cache named A.
  2) Coincidentally, the kmem_cache A is an alias for kmem_cache B,
     so the refcount of B is just increased.
  3) Use kmem_cache_destroy() to destroy the kmem_cache A, just
     decrease the B's refcount but mark the B as dying.
  4) Create a new memory cgroup and alloc memory from the kmem_cache
     B. It leads to create a non-root kmem_cache for allocating memory.
  5) When destroy the memory cgroup created in the step 4), the
     non-root kmem_cache can never be destroyed.

If we repeat steps 4) and 5), this will cause a lot of memory leak.  So
only when refcount reach zero, we mark the root kmem_cache as dying.

Link: http://lkml.kernel.org/r/20200716165103.83462-1-songmuchun@bytedance.com
Fixes: 92ee383f6daa ("mm: fix race between kmem_cache destroy, create and deactivate")
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Acked-by: Roman Gushchin <guro@fb.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/slab_common.c |   35 ++++++++++++++++++++++++++++-------
 1 file changed, 28 insertions(+), 7 deletions(-)

--- a/mm/slab_common.c~mm-memcg-slab-fix-memory-leak-at-non-root-kmem_cache-destroy
+++ a/mm/slab_common.c
@@ -326,6 +326,14 @@ int slab_unmergeable(struct kmem_cache *
 	if (s->refcount < 0)
 		return 1;
 
+#ifdef CONFIG_MEMCG_KMEM
+	/*
+	 * Skip the dying kmem_cache.
+	 */
+	if (s->memcg_params.dying)
+		return 1;
+#endif
+
 	return 0;
 }
 
@@ -886,12 +894,15 @@ static int shutdown_memcg_caches(struct
 	return 0;
 }
 
-static void flush_memcg_workqueue(struct kmem_cache *s)
+static void memcg_set_kmem_cache_dying(struct kmem_cache *s)
 {
 	spin_lock_irq(&memcg_kmem_wq_lock);
 	s->memcg_params.dying = true;
 	spin_unlock_irq(&memcg_kmem_wq_lock);
+}
 
+static void flush_memcg_workqueue(struct kmem_cache *s)
+{
 	/*
 	 * SLAB and SLUB deactivate the kmem_caches through call_rcu. Make
 	 * sure all registered rcu callbacks have been invoked.
@@ -923,10 +934,6 @@ static inline int shutdown_memcg_caches(
 {
 	return 0;
 }
-
-static inline void flush_memcg_workqueue(struct kmem_cache *s)
-{
-}
 #endif /* CONFIG_MEMCG_KMEM */
 
 void slab_kmem_cache_release(struct kmem_cache *s)
@@ -944,8 +951,6 @@ void kmem_cache_destroy(struct kmem_cach
 	if (unlikely(!s))
 		return;
 
-	flush_memcg_workqueue(s);
-
 	get_online_cpus();
 	get_online_mems();
 
@@ -955,6 +960,22 @@ void kmem_cache_destroy(struct kmem_cach
 	if (s->refcount)
 		goto out_unlock;
 
+#ifdef CONFIG_MEMCG_KMEM
+	memcg_set_kmem_cache_dying(s);
+
+	mutex_unlock(&slab_mutex);
+
+	put_online_mems();
+	put_online_cpus();
+
+	flush_memcg_workqueue(s);
+
+	get_online_cpus();
+	get_online_mems();
+
+	mutex_lock(&slab_mutex);
+#endif
+
 	err = shutdown_memcg_caches(s);
 	if (!err)
 		err = shutdown_cache(s);
_

  parent reply index

Thread overview: 86+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-24  4:14 incoming Andrew Morton
2020-07-24  4:15 ` [patch 01/15] mm/memory.c: avoid access flag update TLB flush for retried page fault Andrew Morton
     [not found]   ` <30cf7356-bef1-c621-60cb-e12a8bd9111d@linux.alibaba.com>
2020-07-24  4:56     ` Andrew Morton
2020-07-24  4:15 ` [patch 02/15] mm/mmap.c: close race between munmap() and expand_upwards()/downwards() Andrew Morton
2020-07-24  4:15 ` [patch 03/15] vfs/xattr: mm/shmem: kernfs: release simple xattr entry in a right way Andrew Morton
2020-07-24  4:15 ` [patch 04/15] mm: initialize return of vm_insert_pages Andrew Morton
2020-07-24  4:15 ` [patch 05/15] mm/memcontrol: fix OOPS inside mem_cgroup_get_nr_swap_pages() Andrew Morton
2020-07-24  4:15 ` [patch 06/15] mm/memcg: fix refcount error while moving and swapping Andrew Morton
2020-07-24  4:15 ` Andrew Morton [this message]
2020-07-24  4:15 ` [patch 08/15] mm/hugetlb: avoid hardcoding while checking if cma is enabled Andrew Morton
2020-07-24  4:15 ` [patch 09/15] khugepaged: fix null-pointer dereference due to race Andrew Morton
2020-07-24  4:15 ` [patch 10/15] mailmap: add entry for Mike Rapoport Andrew Morton
2020-07-24  4:15 ` [patch 11/15] squashfs: fix length field overlap check in metadata reading Andrew Morton
2020-07-24  4:15 ` [patch 12/15] scripts/decode_stacktrace: strip basepath from all paths Andrew Morton
2020-07-24  4:15 ` [patch 13/15] io-mapping: indicate mapping failure Andrew Morton
2020-07-24  4:15 ` [patch 14/15] MAINTAINERS: add KCOV section Andrew Morton
2020-07-24  4:15 ` [patch 15/15] scripts/gdb: fix lx-symbols 'gdb.error' while loading modules Andrew Morton
2020-07-27 19:47 ` + mm-remove-unnecessary-wrapper-function-do_mmap_pgoff.patch added to -mm tree Andrew Morton
2020-07-27 19:56 ` + nilfs2-only-call-unlock_new_inode-if-i_new.patch " Andrew Morton
2020-07-27 19:57 ` + nilfs2-convert-__nilfs_msg-to-integrate-the-level-and-format.patch " Andrew Morton
2020-07-27 19:57 ` + nilfs2-use-a-more-common-logging-style.patch " Andrew Morton
2020-07-27 19:58 ` + checkpatch-add-test-for-repeated-words.patch " Andrew Morton
2020-07-27 20:05 ` + ocfs2-replace-http-links-with-https-ones.patch " Andrew Morton
2020-07-27 20:09 ` + ocfs2-fix-unbalanced-locking.patch " Andrew Morton
2020-07-27 20:10 ` + kernelh-remove-duplicate-include-of-asm-div64h.patch " Andrew Morton
2020-07-27 20:11 ` + tools-replace-http-links-with-https-ones.patch " Andrew Morton
2020-07-27 20:12 ` + lib-replace-http-links-with-https-ones.patch " Andrew Morton
2020-07-27 20:12 ` + include-replace-http-links-with-https-ones.patch " Andrew Morton
2020-07-27 20:34 ` + mm-make-mm-locked_vm-an-atomic64-counter.patch " Andrew Morton
2020-07-27 20:34 ` + mm-util-account_locked_vm-does-not-hold-mmap_lock.patch " Andrew Morton
2020-07-27 20:37 ` + cg_read_strcmp-fix-null-pointer-dereference.patch " Andrew Morton
2020-07-27 20:51 ` + mm-hugetlb-add-mempolicy-check-in-the-reservation-routine.patch " Andrew Morton
2020-07-27 20:52 ` [withdrawn] checkpatch-support-deprecated-terms-checking.patch removed from " Andrew Morton
2020-07-27 23:47 ` [obsolete] scripts-deprecated_terms-recommend-denylist-allowlist-instead-of-blacklist-whitelist.patch " Andrew Morton
2020-07-27 23:50 ` [obsolete] scripts-deprecated_terms-sync-with-inclusive-terms.patch " Andrew Morton
2020-07-28  0:18 ` [failures] mm-hugetlb-add-mempolicy-check-in-the-reservation-routine.patch " Andrew Morton
2020-07-28  1:19 ` mmotm 2020-07-27-18-18 uploaded Andrew Morton
     [not found]   ` <ae87385b-f830-dbdf-ebc7-1afb82a7fed0@infradead.org>
2020-07-28 21:55     ` mmotm 2020-07-27-18-18 uploaded (mm/page_alloc.c) Andrew Morton
     [not found]       ` <20200729082053.6c2fb654@canb.auug.org.au>
2020-07-28 22:31         ` Andrew Morton
     [not found]       ` <048cef07-ad4b-8788-94a4-e144de731ab6@infradead.org>
2020-07-29  1:44         ` Andrew Morton
2020-07-28 20:53 ` + mm-mempolicy-fix-kerneldoc-of-numa_map_to_online_node.patch added to -mm tree Andrew Morton
2020-07-28 20:53 ` + mm-mmu_notifier-fix-and-extend-kerneldoc.patch " Andrew Morton
2020-07-28 20:54 ` + mm-swap-fix-kerneldoc-of-swap_vma_readahead.patch " Andrew Morton
2020-07-28 20:58 ` + mm-memcontrol-dont-count-limit-setting-reclaim-as-memory-pressure.patch " Andrew Morton
2020-07-28 21:01 ` + mm-memcontrol-restore-proper-dirty-throttling-when-memoryhigh-changes.patch " Andrew Morton
2020-07-28 22:06 ` + mm-compaction-correct-the-comments-of-compact_defer_shift.patch " Andrew Morton
2020-07-28 22:09 ` + selftests-add-mincore-tests.patch " Andrew Morton
2020-07-28 22:16 ` + proc-pid-smaps-consistent-whitespace-output-format.patch " Andrew Morton
2020-07-28 22:21 ` + xtensa-switch-to-generic-version-of-pte-allocation-fix.patch " Andrew Morton
2020-07-28 22:21 ` Andrew Morton
2020-07-29 21:49 ` + mm-slab-avoid-the-use-of-one-element-array-and-use-struct_size-helper.patch " Andrew Morton
2020-07-29 23:52 ` [obsolete] mm-slab-avoid-the-use-of-one-element-array-and-use-struct_size-helper.patch removed from " Andrew Morton
2020-07-31 19:24 ` + kasan-dont-tag-stacks-allocated-with-pagealloc.patch added to " Andrew Morton
2020-07-31 19:24 ` + kasan-arm64-dont-instrument-functions-that-enable-kasan.patch " Andrew Morton
2020-07-31 19:24 ` + kasan-allow-enabling-stack-tagging-for-tag-based-mode.patch " Andrew Morton
2020-07-31 19:24 ` + kasan-adjust-kasan_stack_oob-for-tag-based-mode.patch " Andrew Morton
2020-07-31 20:00 ` [obsolete] mmhwpoison-rework-soft-offline-for-in-use-pages-fix.patch removed from " Andrew Morton
2020-07-31 20:05 ` + mmhwpoison-cleanup-unused-pagehuge-check.patch added to " Andrew Morton
2020-07-31 20:05 ` + mm-hwpoison-remove-recalculating-hpage.patch " Andrew Morton
2020-07-31 20:05 ` + mmmadvise-call-soft_offline_page-without-mf_count_increased.patch " Andrew Morton
2020-07-31 20:05 ` + mmmadvise-refactor-madvise_inject_error.patch " Andrew Morton
2020-07-31 20:05 ` + mmhwpoison-inject-dont-pin-for-hwpoison_filter.patch " Andrew Morton
2020-07-31 20:05 ` + mmhwpoison-un-export-get_hwpoison_page-and-make-it-static.patch " Andrew Morton
2020-07-31 20:05 ` + mmhwpoison-kill-put_hwpoison_page.patch " Andrew Morton
2020-07-31 20:06 ` + mmhwpoison-remove-mf_count_increased.patch " Andrew Morton
2020-07-31 20:06 ` + mmhwpoison-remove-flag-argument-from-soft-offline-functions.patch " Andrew Morton
2020-07-31 20:06 ` + mmhwpoison-unify-thp-handling-for-hard-and-soft-offline.patch " Andrew Morton
2020-07-31 20:06 ` + mmhwpoison-rework-soft-offline-for-free-pages.patch " Andrew Morton
2020-07-31 20:06 ` + mmhwpoison-rework-soft-offline-for-in-use-pages.patch " Andrew Morton
2020-07-31 20:06 ` + mmhwpoison-refactor-soft_offline_huge_page-and-__soft_offline_page.patch " Andrew Morton
2020-07-31 20:06 ` + mmhwpoison-return-0-if-the-page-is-already-poisoned-in-soft-offline.patch " Andrew Morton
2020-07-31 20:06 ` + mmhwpoison-introduce-mf_msg_unsplit_thp.patch " Andrew Morton
2020-07-31 20:06 ` + mmhwpoison-double-check-page-count-in-__get_any_page.patch " Andrew Morton
2020-07-31 20:23 ` + mm-gup-restrict-cma-region-by-using-allocation-scope-api.patch " Andrew Morton
2020-07-31 20:23 ` + mm-hugetlb-make-hugetlb-migration-callback-cma-aware.patch " Andrew Morton
2020-07-31 20:23 ` + mm-gup-use-a-standard-migration-target-allocation-callback.patch " Andrew Morton
2020-07-31 20:25 ` + mm-migrate-make-a-standard-migration-target-allocation-function-fix.patch " Andrew Morton
2020-07-31 20:26 ` + mm-memcontrol-decouple-reference-counting-from-page-accounting-fix.patch " Andrew Morton
2020-07-31 20:32 ` + mm-dmapoolc-add-warn_on-in-dma_pool_destroy.patch " Andrew Morton
2020-07-31 20:49 ` + kstrto-correct-documentation-references-to-simple_strto.patch " Andrew Morton
2020-07-31 20:49 ` + kstrto-do-not-describe-simple_strto-as-obsolete-replaced.patch " Andrew Morton
2020-07-31 20:57 ` + mm-hugetlb-fix-calculation-of-adjust_range_if_pmd_sharing_possible.patch " Andrew Morton
2020-07-31 20:59 ` + poison-remove-obsolete-comment.patch " Andrew Morton
2020-07-31 21:02 ` + cma-dont-quit-at-first-error-when-activating-reserved-areas.patch " Andrew Morton
2020-07-31 21:10 ` [nacked] mm-dmapoolc-add-warn_on-in-dma_pool_destroy.patch removed from " Andrew Morton
2020-07-31 23:46 ` mmotm 2020-07-31-16-45 uploaded Andrew Morton

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