linux-kernel - Re: [PATCH 1/1] mm: vmalloc: Add a scan area of VA only once

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Date: Sun, 4 Feb 2024 19:44:55 +0000
From: Lorenzo Stoakes <lstoakes@...il.com>
To: "Uladzislau Rezki (Sony)" <urezki@...il.com>
Cc: linux-mm@...ck.org, Andrew Morton <akpm@...ux-foundation.org>,
	LKML <linux-kernel@...r.kernel.org>, Baoquan He <bhe@...hat.com>,
	Christoph Hellwig <hch@...radead.org>,
	Matthew Wilcox <willy@...radead.org>,
	Dave Chinner <david@...morbit.com>,
	Oleksiy Avramchenko <oleksiy.avramchenko@...y.com>
Subject: Re: [PATCH 1/1] mm: vmalloc: Add a scan area of VA only once

On Fri, Feb 02, 2024 at 08:06:28PM +0100, Uladzislau Rezki (Sony) wrote:
> Invoke a kmemleak_scan_area() function only for newly allocated
> objects to add a scan area within that object. There is no reason
> to add a same scan area(pointer to beginning or inside the object)
> several times. If a VA is obtained from the cache its scan area
> has already been associated.
>
> Fixes: 7db166b4aa0d ("mm: vmalloc: offload free_vmap_area_lock lock")
> Signed-off-by: Uladzislau Rezki (Sony) <urezki@...il.com>
> ---
>  mm/vmalloc.c | 12 ++++++------
>  1 file changed, 6 insertions(+), 6 deletions(-)
>
> diff --git a/mm/vmalloc.c b/mm/vmalloc.c
> index 449f45b0e474..25a8df497255 100644
> --- a/mm/vmalloc.c
> +++ b/mm/vmalloc.c
> @@ -1882,13 +1882,13 @@ static struct vmap_area *alloc_vmap_area(unsigned long size,
>  		va = kmem_cache_alloc_node(vmap_area_cachep, gfp_mask, node);
>  		if (unlikely(!va))
>  			return ERR_PTR(-ENOMEM);
> -	}
>
> -	/*
> -	 * Only scan the relevant parts containing pointers to other objects
> -	 * to avoid false negatives.
> -	 */
> -	kmemleak_scan_area(&va->rb_node, SIZE_MAX, gfp_mask);
> +		/*
> +		 * Only scan the relevant parts containing pointers to other objects
> +		 * to avoid false negatives.
> +		 */
> +		kmemleak_scan_area(&va->rb_node, SIZE_MAX, gfp_mask);
> +	}
>
>  retry:
>  	if (addr == vend) {
> --
> 2.39.2
>

Looks good to me, feel free to add:

Reviewed-by: Lorenzo Stoakes <lstoakes@...il.com>