Re: [PATCH v2] mm/page_ext: fix an imbalance with kmemleak

From: Catalin Marinas <catalin.marinas@arm.com>
To: Qian Cai <cai@lca.pw>
Cc: akpm@linux-foundation.org, linux-mm@kvack.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2] mm/page_ext: fix an imbalance with kmemleak
Date: Wed, 27 Feb 2019 17:26:45 +0000	[thread overview]
Message-ID: <20190227172644.GF125513@arrakis.emea.arm.com> (raw)
In-Reply-To: <20190227172445.75553-1-cai@lca.pw>

On Wed, Feb 27, 2019 at 12:24:45PM -0500, Qian Cai wrote:
> After offlined a memory block, kmemleak scan will trigger a crash, as it
> encounters a page ext address that has already been freed during memory
> offlining. At the beginning in alloc_page_ext(), it calls
> kmemleak_alloc(), but it does not call kmemleak_free() in
> free_page_ext().
[...]
> diff --git a/mm/page_ext.c b/mm/page_ext.c
> index 8c78b8d45117..0b6637d7bae9 100644
> --- a/mm/page_ext.c
> +++ b/mm/page_ext.c
> @@ -274,6 +274,7 @@ static void free_page_ext(void *addr)
>  
>  		BUG_ON(PageReserved(page));
>  		free_pages_exact(addr, table_size);
> +		kmemleak_free(addr);

Same comment as for v1, call kmemleak_free() before free_pages_exact().
With that:

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