Re: [PATCH] mm/slub: mark racy access on slab->freelist

[David Rientjes <rientjes@google.com>]

On Sat, 27 Apr 2024, linke li wrote:

> In deactivate_slab(), slab->freelist can be changed concurrently. Mark
> data race on slab->freelist as benign using READ_ONCE.
> 
> This patch is aimed at reducing the number of benign races reported by
> KCSAN in order to focus future debugging effort on harmful races.
> 

Thanks!  Do you have a data race report to copy+paste into the commit 
description so people can search for it if they stumble across the same 
thing?

> Signed-off-by: linke li <lilinke99@qq.com>
> ---
>  mm/slub.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/mm/slub.c b/mm/slub.c
> index 0d700f6ca547..bb0e05a321e9 100644
> --- a/mm/slub.c
> +++ b/mm/slub.c
> @@ -2813,7 +2813,7 @@ static void deactivate_slab(struct kmem_cache *s, struct slab *slab,
>  	struct slab new;
>  	struct slab old;
>  
> -	if (slab->freelist) {
> +	if (READ_ONCE(slab->freelist)) {
>  		stat(s, DEACTIVATE_REMOTE_FREES);
>  		tail = DEACTIVATE_TO_TAIL;
>  	}
> -- 
> 2.39.3 (Apple Git-146)
> 
>