Re: rte_memzone_reserve and invalid socket id

[Tyler Retzlaff <roretzla@linux.microsoft.com>]

On Mon, Mar 28, 2022 at 11:04:36PM -0700, Tyler Retzlaff wrote:
> hi,
> 
> there is a repeatable test failure in test_memzone when running
> dpdk-test.exe --no-huge for memzone_autotest
> 
> it's clear why the test fails but what isn't clear if what
> rte_memzone_reserve is doing when provided an invalid socket id is
> sensible or not.
> 
> as a matter of luck the system i'm using to test is a single socket
> system and as a result has only socket_id 0. the test however tries to
> use rte_memzone_reserve with a socket_id of 1 which is not a valid
> socket_id on the system.
> 
> 	memzone3 = rte_memzone_reserve(TEST_MEMZONE_NAME("testzone3"), 1000,
> 				1, 0);
>                                 ^ socket_id (to repeat just make it invalid)
> 
> the parameter documentation provided for reference.
> 
>  * @param socket_id
>  *   The socket identifier in the case of
>  *   NUMA. The value can be SOCKET_ID_ANY if there is no NUMA
>  *   constraint for the reserved zone.
> 
> of interest is should rte_memzone_reserve fail when provided a
> completely invalid socket_id?
> 
> when running with --no-huge it does not because when --no-huge the
> socket_id no matter the value is silently re-mapped to SOCKET_ID_ANY
> though without --no-huge if a completely garbage socket_id were provided
> it seems the allocation would fail.
> 
> so you get different behavior for an invalid socket_id depending on
> --no-huge vs with.
> 
> 	if (!rte_eal_has_hugepages() && socket_id < RTE_MAX_NUMA_NODES)
> 		socket_id = SOCKET_ID_ANY;
> 
> the test later fails at this check. where it compares the memzone3
> socket_id to what was used in the call to rte_memzone_reserve.
> 
> 	if (memzone3 != NULL && memzone3->socket_id != 1)
> 		return -1;                ^ SOCKET_ID_ANY if --no-huge
> 
> if the allocation had failed, the test would pass instead of failing at
> this point.
> 
> so what's wrong here? the test should be changed to expect different
> behavior with --no-huge vs huge or should rte_memzone_reserve be
> explicitly requiring SOCKET_ID_ANY instead of re-mapping invalid socket
> id?
> 
> if it isn't the test that is wrong then a compatibility discussion is of
> interest but i'm avoiding that until someone confirms the intended
> design/behavior.
> 
> thanks

ping? does the community have an opinion here?