Re: [PATCH v2 4/4] mm: kmemleak: kmemleak_*_phys() set address type and check PA when scan

[Catalin Marinas <catalin.marinas@arm.com>]

On Fri, Jun 03, 2022 at 11:54:15AM +0800, Patrick Wang wrote:
> diff --git a/mm/kmemleak.c b/mm/kmemleak.c
> index 246a70b7218f..62d1ad8f8a44 100644
> --- a/mm/kmemleak.c
> +++ b/mm/kmemleak.c
> @@ -1156,8 +1156,12 @@ EXPORT_SYMBOL(kmemleak_no_scan);
>  void __ref kmemleak_alloc_phys(phys_addr_t phys, size_t size, int min_count,
>  			       gfp_t gfp)
>  {
> -	if (PHYS_PFN(phys) >= min_low_pfn && PHYS_PFN(phys) < max_low_pfn)
> -		kmemleak_alloc(__va(phys), size, min_count, gfp);
> +	pr_debug("%s(0x%pa, %zu, %d)\n", __func__, &phys, size, min_count);
> +
> +	if (kmemleak_enabled && !min_count)
> +		/* create object with OBJECT_PHYS flag */
> +		create_object((unsigned long)phys, size, min_count,
> +			      gfp, true);
>  }

With an early patch, just drop min_count altogether from this API,
assume 0.

>  EXPORT_SYMBOL(kmemleak_alloc_phys);
>  
> @@ -1170,8 +1174,10 @@ EXPORT_SYMBOL(kmemleak_alloc_phys);
>   */
>  void __ref kmemleak_free_part_phys(phys_addr_t phys, size_t size)
>  {
> -	if (PHYS_PFN(phys) >= min_low_pfn && PHYS_PFN(phys) < max_low_pfn)
> -		kmemleak_free_part(__va(phys), size);
> +	pr_debug("%s(0x%pa)\n", __func__, &phys);
> +
> +	if (kmemleak_enabled)
> +		delete_object_part((unsigned long)phys, size, true);
>  }
>  EXPORT_SYMBOL(kmemleak_free_part_phys);
>  
> @@ -1182,8 +1188,10 @@ EXPORT_SYMBOL(kmemleak_free_part_phys);
>   */
>  void __ref kmemleak_not_leak_phys(phys_addr_t phys)
>  {
> -	if (PHYS_PFN(phys) >= min_low_pfn && PHYS_PFN(phys) < max_low_pfn)
> -		kmemleak_not_leak(__va(phys));
> +	pr_debug("%s(0x%pa)\n", __func__, &phys);
> +
> +	if (kmemleak_enabled)
> +		make_gray_object((unsigned long)phys, true);
>  }
>  EXPORT_SYMBOL(kmemleak_not_leak_phys);

This function doesn't have any callers, so please remove it.

> @@ -1194,8 +1202,10 @@ EXPORT_SYMBOL(kmemleak_not_leak_phys);
>   */
>  void __ref kmemleak_ignore_phys(phys_addr_t phys)
>  {
> -	if (PHYS_PFN(phys) >= min_low_pfn && PHYS_PFN(phys) < max_low_pfn)
> -		kmemleak_ignore(__va(phys));
> +	pr_debug("%s(0x%pa)\n", __func__, &phys);
> +
> +	if (kmemleak_enabled)
> +		make_black_object((unsigned long)phys, true);
>  }
>  EXPORT_SYMBOL(kmemleak_ignore_phys);

Ah, that's still in use and we do need make_black_object(), contrary to
what I commented on a previous patch. We can still avoid changing
make_gray_object().

(we could replace the kmemleak_ignore_phys() calls
kmemleak_free_part_phys() but that's not in line with what we do for the
virtual objects)

> @@ -1468,6 +1478,17 @@ static void kmemleak_scan(void)
>  			dump_object_info(object);
>  		}
>  #endif
> +
> +		/* ignore objects outside lowmem (paint them black) */
> +		if ((object->flags & OBJECT_PHYS) &&
> +		   !(object->flags & OBJECT_NO_SCAN)) {
> +			unsigned long phys = object->pointer;
> +
> +			if (PHYS_PFN(phys) < min_low_pfn ||
> +			    PHYS_PFN(phys + object->size) >= max_low_pfn)
> +				__paint_it(object, KMEMLEAK_BLACK);
> +		}
> +
>  		/* reset the reference count (whiten the object) */
>  		object->count = 0;
>  		if (color_gray(object) && get_object(object))

This looks fine.

-- 
Catalin