linux-kernel - Re: [PATCH v2] mm/memmap: Prevent double scanning of memmap by kmemleak

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Message-ID: <Z3fz7_1_-dwnHOtb@arm.com>
Date: Fri, 3 Jan 2025 14:27:59 +0000
From: Catalin Marinas <catalin.marinas@....com>
To: Guo Weikang <guoweikang.kernel@...il.com>
Cc: Mike Rapoport <rppt@...nel.org>,
	Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] mm/memmap: Prevent double scanning of memmap by
 kmemleak

On Fri, Jan 03, 2025 at 07:01:50PM +0800, Guo Weikang wrote:
> diff --git a/mm/mm_init.c b/mm/mm_init.c
> index 24b68b425afb..71b58f5f2492 100644
> --- a/mm/mm_init.c
> +++ b/mm/mm_init.c
> @@ -1580,6 +1580,10 @@ static void __init free_area_init_core(struct pglist_data *pgdat)
>  	}
>  }
>  
> +/*
> + * Kmemleak will explicitly scan mem_map by traversing all valid `struct *page`,
> + * so memblock does not need to be added to the scan list.
> + */
>  void __init *memmap_alloc(phys_addr_t size, phys_addr_t align,
>  			  phys_addr_t min_addr, int nid, bool exact_nid)
>  {

Nitpick: normally I'd place the comment in the code, before the 'if'
statement. We keep the comments above functions for a description of
the function.

> @@ -1587,11 +1591,11 @@ void __init *memmap_alloc(phys_addr_t size, phys_addr_t align,
>  
>  	if (exact_nid)
>  		ptr = memblock_alloc_exact_nid_raw(size, align, min_addr,
> -						   MEMBLOCK_ALLOC_ACCESSIBLE,
> +						   MEMBLOCK_ALLOC_NOLEAKTRACE,
>  						   nid);
>  	else
>  		ptr = memblock_alloc_try_nid_raw(size, align, min_addr,
> -						 MEMBLOCK_ALLOC_ACCESSIBLE,
> +						 MEMBLOCK_ALLOC_NOLEAKTRACE,
>  						 nid);
>  
>  	if (ptr && size > 0)
> diff --git a/mm/sparse-vmemmap.c b/mm/sparse-vmemmap.c
> index cec67c5f37d8..903a5422907b 100644
> --- a/mm/sparse-vmemmap.c
> +++ b/mm/sparse-vmemmap.c
> @@ -27,7 +27,7 @@
>  #include <linux/spinlock.h>
>  #include <linux/vmalloc.h>
>  #include <linux/sched.h>
> -
> +#include "internal.h"
>  #include <asm/dma.h>
>  #include <asm/pgalloc.h>

Another nit: if the original authors of this file preferred the includes
to be in blocks, I'd keep the internal.h include as a separate block
after the asm/ includes.

Apart from these minor things, the patch looks fine.

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

Thanks.

-- 
Catalin