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

[Thomas Monjalon <thomas@monjalon.net>]

29/01/2021 17:07, Burakov, Anatoly:
> 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>
> >> ---
[...]
> >> +	/*
> >> +	 * 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.
> >> +	 */

Applied with minor changes, thanks.