Re: [dpdk-dev] [PATCH] mem: fix deadlock on secondary allocation

["Burakov, Anatoly" <anatoly.burakov@intel.com>]

On 29-Jan-21 3:40 PM, Thomas Monjalon wrote:
> 29/01/2021 16:29, Anatoly Burakov:
>> Previous fix used `rte_malloc_heap_socket_is_external()` to check if the
>> heap was an external heap. However, that API is thread-safe, and when
>> we're inside the allocation process, we're already write-locked, so
>> calling `rte_malloc_heap_socket_is_external()` will result in a
>> deadlock followed by a timeout.
>>
>> Fix it by replacing the API call with a check against maximum number of
>> NUMA nodes, because external heaps always have higher socket ID's.
> 
> Is there some unit tests for such thing?

I couldn't reproduce this using autotests, but Jim has SPDK tests which 
triggered this error.

Since this is dependent upon secondary process, any test would 
necessarily have to be manual here, i think.

> 
>>
>> Fixes: 7ac31e82bc8f ("mem: improve parameter checking on memory hotplug")
>>
>> Reported-by: Jim Harris <james.r.harris@intel.com>
>>
> 
> No need of blank line here.

Need to update my scripts :P

> 
>> Signed-off-by: Anatoly Burakov <anatoly.burakov@intel.com>
>> ---
>>   lib/librte_eal/common/malloc_mp.c | 9 +++++++--
>>   1 file changed, 7 insertions(+), 2 deletions(-)
>>
>> diff --git a/lib/librte_eal/common/malloc_mp.c b/lib/librte_eal/common/malloc_mp.c
>> index 0b19d4d5fb..b1f7f7824b 100644
>> --- a/lib/librte_eal/common/malloc_mp.c
>> +++ b/lib/librte_eal/common/malloc_mp.c
>> -	/* for allocations, we must only use internal heaps */
>> -	if (rte_malloc_heap_socket_is_external(heap->socket_id)) {
>> +	/*
>> +	 * for allocations, we must only use internal heaps, but since the
>> +	 * rte_malloc_heap_socket_is_external() is thread-safe and we're already
>> +	 * read-locked, we'll have to take advantage of the fac that internal
> 
> fac -> fact?
> 

Yes.

>> +	 * socket ID's are always lower than RTE_MAX_NUMA_NODES.
>> +	 */
>> +	if (heap->socket_id >= RTE_MAX_NUMA_NODES) {
> 
> 
> 
> 


-- 
Thanks,
Anatoly