[PATCH 15/15] kasan: use stack_depot_evict for tag-based modes

[andrey.konovalov@linux.dev]

From: Andrey Konovalov <andreyknvl@google.com>

Evict stack traces from the stack depot for the tag-based KASAN modes
once they are evicted from the stack ring.

Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
---
 mm/kasan/tags.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/mm/kasan/tags.c b/mm/kasan/tags.c
index 7dcfe341d48e..fa6b0f77a7dd 100644
--- a/mm/kasan/tags.c
+++ b/mm/kasan/tags.c
@@ -96,7 +96,7 @@ static void save_stack_info(struct kmem_cache *cache, void *object,
 			gfp_t gfp_flags, bool is_free)
 {
 	unsigned long flags;
-	depot_stack_handle_t stack;
+	depot_stack_handle_t stack, old_stack;
 	u64 pos;
 	struct kasan_stack_ring_entry *entry;
 	void *old_ptr;
@@ -120,6 +120,8 @@ static void save_stack_info(struct kmem_cache *cache, void *object,
 	if (!try_cmpxchg(&entry->ptr, &old_ptr, STACK_RING_BUSY_PTR))
 		goto next; /* Busy slot. */
 
+	old_stack = READ_ONCE(entry->stack);
+
 	WRITE_ONCE(entry->size, cache->object_size);
 	WRITE_ONCE(entry->pid, current->pid);
 	WRITE_ONCE(entry->stack, stack);
@@ -131,6 +133,9 @@ static void save_stack_info(struct kmem_cache *cache, void *object,
 	smp_store_release(&entry->ptr, (s64)object);
 
 	read_unlock_irqrestore(&stack_ring.lock, flags);
+
+	if (old_stack)
+		stack_depot_evict(old_stack);
 }
 
 void kasan_save_alloc_info(struct kmem_cache *cache, void *object, gfp_t flags)
-- 
2.25.1