Re: [PATCH] mm/cma: cma_declare_contiguous: correct err handling

From: Andrew Morton <akpm@linux-foundation.org>
To: Peng Fan <peng.fan@nxp.com>
Cc: "labbott@redhat.com" <labbott@redhat.com>,
	"mhocko@suse.com" <mhocko@suse.com>,
	"vbabka@suse.cz" <vbabka@suse.cz>,
	"iamjoonsoo.kim@lge.com" <iamjoonsoo.kim@lge.com>,
	"rppt@linux.vnet.ibm.com" <rppt@linux.vnet.ibm.com>,
	"m.szyprowski@samsung.com" <m.szyprowski@samsung.com>,
	"rdunlap@infradead.org" <rdunlap@infradead.org>,
	"andreyknvl@google.com" <andreyknvl@google.com>,
	"linux-mm@kvack.org" <linux-mm@kvack.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"van.freenix@gmail.com" <van.freenix@gmail.com>,
	Mike Rapoport <rppt@linux.ibm.com>
Subject: Re: [PATCH] mm/cma: cma_declare_contiguous: correct err handling
Date: Thu, 14 Feb 2019 12:38:24 -0800	[thread overview]
Message-ID: <20190214123824.fe95cc2e603f75382490bfb4@linux-foundation.org> (raw)
In-Reply-To: <20190214125704.6678-1-peng.fan@nxp.com>

On Thu, 14 Feb 2019 12:45:51 +0000 Peng Fan <peng.fan@nxp.com> wrote:

> In case cma_init_reserved_mem failed, need to free the memblock allocated
> by memblock_reserve or memblock_alloc_range.
> 
> ...
>
> --- a/mm/cma.c
> +++ b/mm/cma.c
> @@ -353,12 +353,14 @@ int __init cma_declare_contiguous(phys_addr_t base,
>  
>  	ret = cma_init_reserved_mem(base, size, order_per_bit, name, res_cma);
>  	if (ret)
> -		goto err;
> +		goto free_mem;
>  
>  	pr_info("Reserved %ld MiB at %pa\n", (unsigned long)size / SZ_1M,
>  		&base);
>  	return 0;
>  
> +free_mem:
> +	memblock_free(base, size);
>  err:
>  	pr_err("Failed to reserve %ld MiB\n", (unsigned long)size / SZ_1M);
>  	return ret;

This doesn't look right to me.  In the `fixed==true' case we didn't
actually allocate anything and in the `fixed==false' case, the
allocated memory is at `addr', not at `base'.