On Wed, 30 Jun 2021 at 15:53, Alexander Potapenko glider@google.com wrote:
Check the allocation size before toggling kfence_allocation_gate. This way allocations that can't be served by KFENCE will not result in waiting for another CONFIG_KFENCE_SAMPLE_INTERVAL without allocating anything.
Suggested-by: Marco Elver elver@google.com Cc: Andrew Morton akpm@linux-foundation.org Cc: Dmitry Vyukov dvyukov@google.com Cc: Marco Elver elver@google.com Cc: Greg Kroah-Hartman gregkh@linuxfoundation.org Cc: stable@vger.kernel.org # 5.12+ Signed-off-by: Alexander Potapenko glider@google.com
Reviewed-by: Marco Elver elver@google.com
mm/kfence/core.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-)
diff --git a/mm/kfence/core.c b/mm/kfence/core.c index 4d21ac44d5d35..33bb20d91bf6a 100644 --- a/mm/kfence/core.c +++ b/mm/kfence/core.c @@ -733,6 +733,13 @@ void kfence_shutdown_cache(struct kmem_cache *s)
void *__kfence_alloc(struct kmem_cache *s, size_t size, gfp_t flags) {
/** Perform size check before switching kfence_allocation_gate, so that* we don't disable KFENCE without making an allocation.*/if (size > PAGE_SIZE)return NULL;/* * allocation_gate only needs to become non-zero, so it doesn't make * sense to continue writing to it and pay the associated contention@@ -757,9 +764,6 @@ void *__kfence_alloc(struct kmem_cache *s, size_t size, gfp_t flags) if (!READ_ONCE(kfence_enabled)) return NULL;
if (size > PAGE_SIZE)return NULL;return kfence_guarded_alloc(s, size, flags);}
-- 2.32.0.93.g670b81a890-goog