External names can be released using kfree_rcu() from release_dentry_name_snapshot() and copy_name(), and it will lead to the imbalance in the indirectly reclaimable memory accounting.
Fix this by introducing __d_free_external_name() and call it from all release paths. Signed-off-by: Roman Gushchin <[email protected]> Cc: Andrew Morton <[email protected]> Cc: Alexander Viro <[email protected]> Cc: Michal Hocko <[email protected]> Cc: Johannes Weiner <[email protected]> Cc: [email protected] Cc: [email protected] Cc: [email protected] Cc: [email protected] --- fs/dcache.c | 18 +++++++++++++----- 1 file changed, 13 insertions(+), 5 deletions(-) diff --git a/fs/dcache.c b/fs/dcache.c index 98826efe22a0..9008057a7460 100644 --- a/fs/dcache.c +++ b/fs/dcache.c @@ -266,16 +266,24 @@ static void __d_free(struct rcu_head *head) kmem_cache_free(dentry_cache, dentry); } -static void __d_free_external(struct rcu_head *head) +static void __d_free_external_name(struct rcu_head *head) { - struct dentry *dentry = container_of(head, struct dentry, d_u.d_rcu); - struct external_name *name = external_name(dentry); + struct external_name *name = container_of(head, struct external_name, + u.head); mod_node_page_state(page_pgdat(virt_to_page(name)), NR_INDIRECTLY_RECLAIMABLE_BYTES, -ksize(name)); kfree(name); +} + +static void __d_free_external(struct rcu_head *head) +{ + struct dentry *dentry = container_of(head, struct dentry, d_u.d_rcu); + + __d_free_external_name(&external_name(dentry)->u.head); + kmem_cache_free(dentry_cache, dentry); } @@ -307,7 +315,7 @@ void release_dentry_name_snapshot(struct name_snapshot *name) struct external_name *p; p = container_of(name->name, struct external_name, name[0]); if (unlikely(atomic_dec_and_test(&p->u.count))) - kfree_rcu(p, u.head); + call_rcu(&p->u.head, __d_free_external_name); } } EXPORT_SYMBOL(release_dentry_name_snapshot); @@ -2769,7 +2777,7 @@ static void copy_name(struct dentry *dentry, struct dentry *target) dentry->d_name.hash_len = target->d_name.hash_len; } if (old_name && likely(atomic_dec_and_test(&old_name->u.count))) - kfree_rcu(old_name, u.head); + call_rcu(&old_name->u.head, __d_free_external_name); } static void dentry_lock_for_move(struct dentry *dentry, struct dentry *target) -- 2.14.3
