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

[Stojaczyk, Dariusz]

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.

> -----Original Message-----
> From: Howell, Seth
> Sent: Friday, December 7, 2018 9:11 PM
> To: Burakov, Anatoly <anatoly.burakov at intel.com>
> Cc: dev at dpdk.org; stable at dpdk.org; Howell, Seth
> <seth.howell at intel.com>; Stojaczyk, Dariusz <dariusz.stojaczyk at 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")
> 
> Signed-off-by: Seth Howell <seth.howell at intel.com>
> Signed-off-by: Darek Stojaczyk <dariusz.stojaczyk at 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