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| author | Uladzislau Rezki (Sony) <urezki@gmail.com> | 2021-04-15 19:19:57 +0200 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@kernel.org> | 2021-05-10 16:00:48 -0700 |
| commit | ac7625ebd5f7bad93f821b7397fe50635f58aa4b (patch) | |
| tree | 90c49b7ecc0f899a41490673c3832547d8177ca2 /kernel/rcu/tree.c | |
| parent | d0bfa8b3c411e25e014e4131d2804afe29c440a6 (diff) | |
| download | linux-ac7625ebd5f7bad93f821b7397fe50635f58aa4b.tar.gz linux-ac7625ebd5f7bad93f821b7397fe50635f58aa4b.tar.xz | |
kvfree_rcu: Use [READ/WRITE]_ONCE() macros to access to nr_bkv_objs
nr_bkv_objs is a count of the objects in the kvfree_rcu page cache.
Accessing it requires holding the ->lock. Switch to READ_ONCE() and
WRITE_ONCE() macros to provide lockless access to this counter.
This lockless access is used for the shrinker.
Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Diffstat (limited to 'kernel/rcu/tree.c')
| -rw-r--r-- | kernel/rcu/tree.c | 14 |
1 files changed, 4 insertions, 10 deletions
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index 74d840aa877b..676a49ab5b2b 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -3250,7 +3250,7 @@ get_cached_bnode(struct kfree_rcu_cpu *krcp) if (!krcp->nr_bkv_objs) return NULL; - krcp->nr_bkv_objs--; + WRITE_ONCE(krcp->nr_bkv_objs, krcp->nr_bkv_objs - 1); return (struct kvfree_rcu_bulk_data *) llist_del_first(&krcp->bkvcache); } @@ -3264,9 +3264,8 @@ put_cached_bnode(struct kfree_rcu_cpu *krcp, return false; llist_add((struct llist_node *) bnode, &krcp->bkvcache); - krcp->nr_bkv_objs++; + WRITE_ONCE(krcp->nr_bkv_objs, krcp->nr_bkv_objs + 1); return true; - } static int @@ -3278,7 +3277,7 @@ drain_page_cache(struct kfree_rcu_cpu *krcp) raw_spin_lock_irqsave(&krcp->lock, flags); page_list = llist_del_all(&krcp->bkvcache); - krcp->nr_bkv_objs = 0; + WRITE_ONCE(krcp->nr_bkv_objs, 0); raw_spin_unlock_irqrestore(&krcp->lock, flags); llist_for_each_safe(pos, n, page_list) { @@ -3682,18 +3681,13 @@ kfree_rcu_shrink_count(struct shrinker *shrink, struct shrink_control *sc) { int cpu; unsigned long count = 0; - unsigned long flags; /* Snapshot count of all CPUs */ for_each_possible_cpu(cpu) { struct kfree_rcu_cpu *krcp = per_cpu_ptr(&krc, cpu); count += READ_ONCE(krcp->count); - - raw_spin_lock_irqsave(&krcp->lock, flags); - count += krcp->nr_bkv_objs; - raw_spin_unlock_irqrestore(&krcp->lock, flags); - + count += READ_ONCE(krcp->nr_bkv_objs); atomic_set(&krcp->backoff_page_cache_fill, 1); } |