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

[Vlastimil Babka]

On 2/14/19 9:38 PM, Andrew Morton wrote:
> On Thu, 14 Feb 2019 12:45:51 +0000 Peng Fan <peng.fan@xxxxxxx> 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'.

I think it's ok as the fixed==true path has "memblock_reserve()", but
better leave this to the memblock maintainer :)

There's also 'kmemleak_ignore_phys(addr)' which should probably be
undone (or not called at all) in the failure case. But it seems to be
missing from the fixed==true path?