Re: [dpdk-stable] [PATCH v2] malloc: notify primary process about hotplug in secondary

[Kevin Traynor <ktraynor@redhat.com>]

On 12/07/2018 12:30 PM, Stojaczyk, Dariusz wrote:
> Hi Kevin, is the merge window for DPDK 18.08.1 and 18.05.2 still open? This fix is critical for multi-process memory hotplug and you might want to pull it in.
> D.
> 

Hi Dariusz,

I can still take patches for 18.08.1 but the patch must be applied in
the main tree before it can be backported. DPDK 18.05 is not maintained
anymore.

>> -----Original Message-----
>> From: Howell, Seth
>> Sent: Friday, December 7, 2018 9:11 PM
>> To: Burakov, Anatoly <anatoly.burakov@intel.com>
>> Cc: dev@dpdk.org; stable@dpdk.org; Howell, Seth
>> <seth.howell@intel.com>; Stojaczyk, Dariusz <dariusz.stojaczyk@intel.com>
>> Subject: [PATCH v2] malloc: notify primary process about hotplug in
>> secondary
>>
>> When secondary process hotplugs memory, it sends a request
>> to primary, which then performs the real mmap() and sends
>> sync requests to all secondary processes. Upon receiving
>> such sync request, each secondary process will notify the
>> upper layers of hotplugged memory (and will call all
>> locally registered event callbacks).
>>
>> In the end we'll end up with memory event callbacks fired
>> in all the processes except the primary, which is a bug.
>>
>> This gets critical if memory is hotplugged while a VFIO
>> device is attached, as the VFIO memory registration -
>> which is done from a memory event callback present in the
>> primary process only - is never called.
>>
>> After this patch, a primary process fires memory event
>> callbacks before secondary processes start their
>> synchronizations - both for hotplug and hotremove.
>>
>> Fixes: 07dcbfe0101f ("malloc: support multiprocess memory hotplug")

In this case I know because you mailed, but for future, 'Cc:
stable@dpdk.org' tag should also be inserted here in the commit message
so it can be found by scripts.

Kevin.

>>
>> Signed-off-by: Seth Howell <seth.howell@intel.com>
>> Signed-off-by: Darek Stojaczyk <dariusz.stojaczyk@intel.com>
>> ---
>>  lib/librte_eal/common/malloc_mp.c | 8 ++++++++
>>  1 file changed, 8 insertions(+)
>>
>> diff --git a/lib/librte_eal/common/malloc_mp.c
>> b/lib/librte_eal/common/malloc_mp.c
>> index 5f2d4e0be..f3a13353b 100644
>> --- a/lib/librte_eal/common/malloc_mp.c
>> +++ b/lib/librte_eal/common/malloc_mp.c
>> @@ -209,6 +209,8 @@ handle_alloc_request(const struct malloc_mp_req
>> *m,
>>
>>  	map_addr = ms[0]->addr;
>>
>> +	eal_memalloc_mem_event_notify(RTE_MEM_EVENT_ALLOC,
>> map_addr, alloc_sz);
>> +
>>  	/* we have succeeded in allocating memory, but we still need to sync
>>  	 * with other processes. however, since DPDK IPC is single-threaded,
>> we
>>  	 * send an asynchronous request and exit this callback.
>> @@ -258,6 +260,9 @@ handle_request(const struct rte_mp_msg *msg,
>> const void *peer __rte_unused)
>>  	if (m->t == REQ_TYPE_ALLOC) {
>>  		ret = handle_alloc_request(m, entry);
>>  	} else if (m->t == REQ_TYPE_FREE) {
>> +		eal_memalloc_mem_event_notify(RTE_MEM_EVENT_FREE,
>> +				m->free_req.addr, m->free_req.len);
>> +
>>  		ret = malloc_heap_free_pages(m->free_req.addr,
>>  				m->free_req.len);
>>  	} else {
>> @@ -436,6 +441,9 @@ handle_sync_response(const struct rte_mp_msg
>> *request,
>>  		memset(&rb_msg, 0, sizeof(rb_msg));
>>
>>  		/* we've failed to sync, so do a rollback */
>> +		eal_memalloc_mem_event_notify(RTE_MEM_EVENT_FREE,
>> +				state->map_addr, state->map_len);
>> +
>>  		rollback_expand_heap(state->ms, state->ms_len, state-
>>> elem,
>>  				state->map_addr, state->map_len);
>>
>> --
>> 2.17.2
>