Re: [PATCH] mm: workingset: fix NULL ptr dereference

[Matthew Wilcox]

On Tue, Apr 10, 2018 at 11:33:39AM +0900, Minchan Kim wrote:
> @@ -522,7 +532,7 @@ EXPORT_SYMBOL(radix_tree_preload);
>   */
>  int radix_tree_maybe_preload(gfp_t gfp_mask)
>  {
> -	if (gfpflags_allow_blocking(gfp_mask))
> +	if (gfpflags_allow_blocking(gfp_mask) && !(gfp_mask & __GFP_ZERO))
>  		return __radix_tree_preload(gfp_mask, RADIX_TREE_PRELOAD_SIZE);
>  	/* Preloading doesn't help anything with this gfp mask, skip it */
>  	preempt_disable();

No, you've completely misunderstood what's going on in this function.