On Thu, Dec 22, 2016 at 10:15:20AM +0100, Michal Hocko wrote:
>On Wed 21-12-16 23:30:33, Wei Yang wrote:
>> memblock_reserve() would add a new range to memblock.reserved in case the
>> new range is not totally covered by any of the current memblock.reserved
>> range. If the memblock.reserved is full and can't resize,
>> memblock_reserve() would fail.
>>
>> This doesn't happen in real world now, I observed this during code review.
>> While theoretically, it has the chance to happen. And if it happens, others
>> would think this range of memory is still available and may corrupt the
>> memory.
>
>OK, this explains it much better than the previous version! The silent
>memory corruption is indeed too hard to debug to have this open even
>when the issue is theoretical.
>
Thanks~ Have a nice day:-)
>> This patch checks the return value and goto "done" after it succeeds.
>>
>> Signed-off-by: Wei Yang <richard.weiyang@xxxxxxxxx>
>
>Acked-by: Michal Hocko <mhocko@xxxxxxxx>
>
>Thanks!
>
>> ---
>> mm/memblock.c | 6 ++----
>> 1 file changed, 2 insertions(+), 4 deletions(-)
>>
>> diff --git a/mm/memblock.c b/mm/memblock.c
>> index 4929e06..d0f2c96 100644
>> --- a/mm/memblock.c
>> +++ b/mm/memblock.c
>> @@ -1274,18 +1274,17 @@ static void * __init memblock_virt_alloc_internal(
>>
>> if (max_addr > memblock.current_limit)
>> max_addr = memblock.current_limit;
>> -
>> again:
>> alloc = memblock_find_in_range_node(size, align, min_addr, max_addr,
>> nid, flags);
>> - if (alloc)
>> + if (alloc && !memblock_reserve(alloc, size))
>> goto done;
>>
>> if (nid != NUMA_NO_NODE) {
>> alloc = memblock_find_in_range_node(size, align, min_addr,
>> max_addr, NUMA_NO_NODE,
>> flags);
>> - if (alloc)
>> + if (alloc && !memblock_reserve(alloc, size))
>> goto done;
>> }
>>
>> @@ -1303,7 +1302,6 @@ static void * __init memblock_virt_alloc_internal(
>>
>> return NULL;
>> done:
>> - memblock_reserve(alloc, size);
>> ptr = phys_to_virt(alloc);
>> memset(ptr, 0, size);
>>
>> --
>> 2.5.0
>
>--
>Michal Hocko
>SUSE Labs
--
Wei Yang
Help you, Help me
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