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

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Date:   Thu, 14 Feb 2019 12:38:24 -0800
From:   Andrew Morton <akpm@...ux-foundation.org>
To:     Peng Fan <peng.fan@....com>
Cc:     "labbott@...hat.com" <labbott@...hat.com>,
        "mhocko@...e.com" <mhocko@...e.com>,
        "vbabka@...e.cz" <vbabka@...e.cz>,
        "iamjoonsoo.kim@....com" <iamjoonsoo.kim@....com>,
        "rppt@...ux.vnet.ibm.com" <rppt@...ux.vnet.ibm.com>,
        "m.szyprowski@...sung.com" <m.szyprowski@...sung.com>,
        "rdunlap@...radead.org" <rdunlap@...radead.org>,
        "andreyknvl@...gle.com" <andreyknvl@...gle.com>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "van.freenix@...il.com" <van.freenix@...il.com>,
        Mike Rapoport <rppt@...ux.ibm.com>
Subject: Re: [PATCH] mm/cma: cma_declare_contiguous: correct err handling

On Thu, 14 Feb 2019 12:45:51 +0000 Peng Fan <peng.fan@....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'.