[PATCH] debugobjects: avoid recursive calls with kmemleak

[PATCH] debugobjects: avoid recursive calls with kmemleak

[Qian Cai]

CONFIG_DEBUG_OBJECTS_RCU_HEAD does not play well with kmemleak due to
recursive calls.

fill_pool
  kmemleak_ignore
    make_black_object
      put_object
        __call_rcu (kernel/rcu/tree.c)
          debug_rcu_head_queue
            debug_object_activate
              debug_object_init
                fill_pool
                  kmemleak_ignore
                    make_black_object
                      ...

Hence, adding SLAB_NOLEAKTRACE to kmem_cache_create() to not register a
newly allocated debug objects at all.

Suggested-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Qian Cai <cai@gmx.us>
---
 lib/debugobjects.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/lib/debugobjects.c b/lib/debugobjects.c
index eab7727b46ed..55437fd5128b 100644
--- a/lib/debugobjects.c
+++ b/lib/debugobjects.c
@@ -135,7 +135,6 @@ static void fill_pool(void)
 		if (!new)
 			return;
 
-		kmemleak_ignore(new);
 		raw_spin_lock_irqsave(&pool_lock, flags);
 		hlist_add_head(&new->node, &obj_pool);
 		debug_objects_allocated++;
@@ -1128,7 +1127,6 @@ static int __init debug_objects_replace_static_objects(void)
 		obj = kmem_cache_zalloc(obj_cache, GFP_KERNEL);
 		if (!obj)
 			goto free;
-		kmemleak_ignore(obj);
 		hlist_add_head(&obj->node, &objects);
 	}
 
@@ -1182,7 +1180,8 @@ void __init debug_objects_mem_init(void)
 
 	obj_cache = kmem_cache_create("debug_objects_cache",
 				      sizeof (struct debug_obj), 0,
-				      SLAB_DEBUG_OBJECTS, NULL);
+				      SLAB_DEBUG_OBJECTS | SLAB_NOLEAKTRACE,
+				      NULL);
 
 	if (!obj_cache || debug_objects_replace_static_objects()) {
 		debug_objects_enabled = 0;
-- 
2.17.2 (Apple Git-113)

Re: [PATCH] debugobjects: avoid recursive calls with kmemleak

[Waiman Long]

On 11/26/2018 11:53 AM, Qian Cai wrote:
> CONFIG_DEBUG_OBJECTS_RCU_HEAD does not play well with kmemleak due to
> recursive calls.
>
> fill_pool
>   kmemleak_ignore
>     make_black_object
>       put_object
>         __call_rcu (kernel/rcu/tree.c)
>           debug_rcu_head_queue
>             debug_object_activate
>               debug_object_init
>                 fill_pool
>                   kmemleak_ignore
>                     make_black_object
>                       ...
>
> Hence, adding SLAB_NOLEAKTRACE to kmem_cache_create() to not register a
> newly allocated debug objects at all.
>
> Suggested-by: Catalin Marinas <catalin.marinas@arm.com>
> Signed-off-by: Qian Cai <cai@gmx.us>
> ---
>  lib/debugobjects.c | 5 ++---
>  1 file changed, 2 insertions(+), 3 deletions(-)
>
> diff --git a/lib/debugobjects.c b/lib/debugobjects.c
> index eab7727b46ed..55437fd5128b 100644
> --- a/lib/debugobjects.c
> +++ b/lib/debugobjects.c
> @@ -135,7 +135,6 @@ static void fill_pool(void)
>  		if (!new)
>  			return;
>  
> -		kmemleak_ignore(new);
>  		raw_spin_lock_irqsave(&pool_lock, flags);
>  		hlist_add_head(&new->node, &obj_pool);
>  		debug_objects_allocated++;
> @@ -1128,7 +1127,6 @@ static int __init debug_objects_replace_static_objects(void)
>  		obj = kmem_cache_zalloc(obj_cache, GFP_KERNEL);
>  		if (!obj)
>  			goto free;
> -		kmemleak_ignore(obj);
>  		hlist_add_head(&obj->node, &objects);
>  	}
>  
> @@ -1182,7 +1180,8 @@ void __init debug_objects_mem_init(void)
>  
>  	obj_cache = kmem_cache_create("debug_objects_cache",
>  				      sizeof (struct debug_obj), 0,
> -				      SLAB_DEBUG_OBJECTS, NULL);
> +				      SLAB_DEBUG_OBJECTS | SLAB_NOLEAKTRACE,
> +				      NULL);
>  
>  	if (!obj_cache || debug_objects_replace_static_objects()) {
>  		debug_objects_enabled = 0;

Acked-by: Waiman Long <longman@redhat.com>

Re: [PATCH] debugobjects: avoid recursive calls with kmemleak

[Catalin Marinas]

On Mon, Nov 26, 2018 at 11:53:43AM -0500, Qian Cai wrote:
> CONFIG_DEBUG_OBJECTS_RCU_HEAD does not play well with kmemleak due to
> recursive calls.
> 
> fill_pool
>   kmemleak_ignore
>     make_black_object
>       put_object
>         __call_rcu (kernel/rcu/tree.c)
>           debug_rcu_head_queue
>             debug_object_activate
>               debug_object_init
>                 fill_pool
>                   kmemleak_ignore
>                     make_black_object
>                       ...
> 
> Hence, adding SLAB_NOLEAKTRACE to kmem_cache_create() to not register a
> newly allocated debug objects at all.
> 
> Suggested-by: Catalin Marinas <catalin.marinas@arm.com>
> Signed-off-by: Qian Cai <cai@gmx.us>

Acked-by: Catalin Marinas <catalin.marinas@arm.com>