Re: [PATCH v3 2/3] mm/sparse: fix possible memory leak

[Gavin Shan <shangw@linux.vnet.ibm.com>]

>> diff --git a/mm/sparse.c b/mm/sparse.c
>> index 781fa04..a6984d9 100644
>> --- a/mm/sparse.c
>> +++ b/mm/sparse.c
>> @@ -75,6 +75,20 @@ static struct mem_section noinline __init_refok *sparse_index_alloc(int nid)
>>  	return section;
>>  }
>>  
>> +static inline void __meminit sparse_index_free(struct mem_section *section)
>> +{
>> +	unsigned long size = SECTIONS_PER_ROOT *
>> +			     sizeof(struct mem_section);
>> +
>> +	if (!section)
>> +		return;
>> +
>> +	if (slab_is_available())
>> +		kfree(section);
>> +	else
>> +		free_bootmem(virt_to_phys(section), size);
>
>Eek, does that work?
>

David, I think it's working fine. If my understanding is wrong, please
correct me. Thanks a lot :-)

The "section" allocated from the bootmem allocator might take following
function call path. In the function alloc_bootmem_core(), all online nodes
will be checked for the memory allocation. So we could have memory allocated
from different node other than the specified one to alloc_bootmem_node()

alloc_bootmem_node(nid, size)
__alloc_bootmem_node()
___alloc_bootmem_node_nopanic()
alloc_bootmem_core()

On the other hand, function free_bootmem() checks which node the memory
block belongs to and then free it into that node. That looks reasonable.

Thanks,
Gavin 

>> +}
>> +
>>  static int __meminit sparse_index_init(unsigned long section_nr, int nid)
>>  {
>>  	static DEFINE_SPINLOCK(index_init_lock);
>> @@ -102,6 +116,9 @@ static int __meminit sparse_index_init(unsigned long section_nr, int nid)
>>  	mem_section[root] = section;
>>  out:
>>  	spin_unlock(&index_init_lock);
>> +	if (ret)
>> +		sparse_index_free(section);
>> +
>>  	return ret;
>>  }
>>  #else /* !SPARSEMEM_EXTREME */
>
>--
>To unsubscribe, send a message with 'unsubscribe linux-mm' in
>the body to majordomo@kvack.org.  For more info on Linux MM,
>see: http://www.linux-mm.org/ .
>Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
>

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>