From: Vladimir Davydov <vdavydov@xxxxxxxxxxxxx> Subject: radix-tree: account nodes to memcg only if explicitly requested Radix trees may be used not only for storing page cache pages, so unconditionally accounting radix tree nodes to the current memory cgroup is bad: if a radix tree node is used for storing data shared among different cgroups we risk pinning dead memory cgroups forever. So let's only account radix tree nodes if it was explicitly requested by passing __GFP_ACCOUNT to INIT_RADIX_TREE. Currently, we only want to account page cache entries, so mark mapping->page_tree so. Fixes: 58e698af4c63 ("radix-tree: account radix_tree_node to memory cgroup") Link: http://lkml.kernel.org/r/1470057188-7864-1-git-send-email-vdavydov@xxxxxxxxxxxxx Signed-off-by: Vladimir Davydov <vdavydov@xxxxxxxxxxxxx> Acked-by: Johannes Weiner <hannes@xxxxxxxxxxx> Acked-by: Michal Hocko <mhocko@xxxxxxxx> Cc: <stable@xxxxxxxxxxxxxxx> [4.6+] Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- fs/inode.c | 2 +- lib/radix-tree.c | 14 ++++++++++---- 2 files changed, 11 insertions(+), 5 deletions(-) diff -puN fs/inode.c~radix-tree-account-nodes-to-memcg-only-if-explicitly-requested fs/inode.c --- a/fs/inode.c~radix-tree-account-nodes-to-memcg-only-if-explicitly-requested +++ a/fs/inode.c @@ -345,7 +345,7 @@ EXPORT_SYMBOL(inc_nlink); void address_space_init_once(struct address_space *mapping) { memset(mapping, 0, sizeof(*mapping)); - INIT_RADIX_TREE(&mapping->page_tree, GFP_ATOMIC); + INIT_RADIX_TREE(&mapping->page_tree, GFP_ATOMIC | __GFP_ACCOUNT); spin_lock_init(&mapping->tree_lock); init_rwsem(&mapping->i_mmap_rwsem); INIT_LIST_HEAD(&mapping->private_list); diff -puN lib/radix-tree.c~radix-tree-account-nodes-to-memcg-only-if-explicitly-requested lib/radix-tree.c --- a/lib/radix-tree.c~radix-tree-account-nodes-to-memcg-only-if-explicitly-requested +++ a/lib/radix-tree.c @@ -277,10 +277,11 @@ radix_tree_node_alloc(struct radix_tree_ /* * Even if the caller has preloaded, try to allocate from the - * cache first for the new node to get accounted. + * cache first for the new node to get accounted to the memory + * cgroup. */ ret = kmem_cache_alloc(radix_tree_node_cachep, - gfp_mask | __GFP_ACCOUNT | __GFP_NOWARN); + gfp_mask | __GFP_NOWARN); if (ret) goto out; @@ -303,8 +304,7 @@ radix_tree_node_alloc(struct radix_tree_ kmemleak_update_trace(ret); goto out; } - ret = kmem_cache_alloc(radix_tree_node_cachep, - gfp_mask | __GFP_ACCOUNT); + ret = kmem_cache_alloc(radix_tree_node_cachep, gfp_mask); out: BUG_ON(radix_tree_is_internal_node(ret)); return ret; @@ -351,6 +351,12 @@ static int __radix_tree_preload(gfp_t gf struct radix_tree_node *node; int ret = -ENOMEM; + /* + * Nodes preloaded by one cgroup can be be used by another cgroup, so + * they should never be accounted to any particular memory cgroup. + */ + gfp_mask &= ~__GFP_ACCOUNT; + preempt_disable(); rtp = this_cpu_ptr(&radix_tree_preloads); while (rtp->nr < nr) { _ -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html