Re: [PATCH] tools/testing/memblock: fix stale NUMA reservation tests

[Mike Rapoport <rppt@kernel.org>]

Hi,

On Mon, Apr 13, 2026 at 09:14:58AM +0000, priyanshukumarpu@gmail.com wrote:
> From: Priyanshu Kumar <priyanshukumarpu@gmail.com>
> 
> memblock allocations now reserve memory with MEMBLOCK_RSRV_KERN and,
> on NUMA configurations, record the requested node on the reserved
> region. Several memblock simulator NUMA tests still expected merges
> that only worked before those reservation semantics changed, so the
> suite aborted even though the allocator behavior was correct.
> 
> Update the NUMA merge expectations in the memblock_alloc_try_nid()
> and memblock_alloc_exact_nid_raw() tests to match the current reserved
> region metadata rules. For cases that should still merge, create the
> pre-existing reservation with matching nid and MEMBLOCK_RSRV_KERN
> metadata. Also strengthen the memblock_alloc_node() coverage by
> checking the newly created reserved region directly instead of
> re-reading the source memory node descriptor.
> 
> Finally, drop the stale README/TODO notes that still claimed
> memblock_alloc_node() could not be tested.
> 
> The memblock simulator passes again with NUMA enabled after these
> updates.
> 
> Signed-off-by: Priyanshu Kumar <priyanshukumarpu@gmail.com>
> ---
>  tools/testing/memblock/README                 |  5 +--
>  tools/testing/memblock/TODO                   |  4 +-
>  .../memblock/tests/alloc_exact_nid_api.c      | 29 +++++++-----
>  tools/testing/memblock/tests/alloc_nid_api.c  | 44 +++++++++++++------
>  4 files changed, 53 insertions(+), 29 deletions(-)
> 
> diff --git a/tools/testing/memblock/README b/tools/testing/memblock/README
> index 7ca437d81806..b435f48d8a70 100644
> --- a/tools/testing/memblock/README
> +++ b/tools/testing/memblock/README
> @@ -104,10 +104,7 @@ called at the beginning of each test.
>  Known issues
>  ============
>  
> -1. Requesting a specific NUMA node via memblock_alloc_node() does not work as
> -   intended. Once the fix is in place, tests for this function can be added.
> -
> -2. Tests for memblock_alloc_low() can't be easily implemented. The function uses
> +1. Tests for memblock_alloc_low() can't be easily implemented. The function uses
>     ARCH_LOW_ADDRESS_LIMIT marco, which can't be changed to point at the low
>     memory of the memory_block.
>  
> diff --git a/tools/testing/memblock/TODO b/tools/testing/memblock/TODO
> index e306c90c535f..c13ad0dae776 100644
> --- a/tools/testing/memblock/TODO
> +++ b/tools/testing/memblock/TODO
> @@ -1,5 +1,5 @@
>  TODO
>  =====
>  
> -1. Add tests for memblock_alloc_node() to check if the correct NUMA node is set
> -   for the new region
> +1. Add tests for memblock_alloc_low() once the simulator can model
> +   ARCH_LOW_ADDRESS_LIMIT against the low memory in memory_block
> diff --git a/tools/testing/memblock/tests/alloc_exact_nid_api.c b/tools/testing/memblock/tests/alloc_exact_nid_api.c
> index 6e14447da6e1..3f5ab994f63a 100644
> --- a/tools/testing/memblock/tests/alloc_exact_nid_api.c
> +++ b/tools/testing/memblock/tests/alloc_exact_nid_api.c
> @@ -368,7 +368,8 @@ static int alloc_exact_nid_bottom_up_numa_part_reserved_check(void)
>  	max_addr = memblock_end_of_DRAM();
>  	total_size = size + r1.size;
>  
> -	memblock_reserve(r1.base, r1.size);
> +	ASSERT_EQ(0, __memblock_reserve(r1.base, r1.size, nid_req,
> +					MEMBLOCK_RSRV_KERN));

No need to check the return value here. 

>  	allocated_ptr = memblock_alloc_exact_nid_raw(size, SMP_CACHE_BYTES,
>  						     min_addr, max_addr,
>  						     nid_req);
> @@ -831,14 +832,17 @@ static int alloc_exact_nid_numa_large_region_generic_check(void)
>   *  |             | r2 |          new          | r1 |                  |
>   *  +-------------+----+-----------------------+----+------------------+
>   *
> - * Expect to merge all of the regions into one. The region counter and total
> - * size fields get updated.
> + * Expect to allocate the requested node as a separate kernel-reserved region.
> + * The neighboring reservations remain distinct because the new region records
> + * the requested NUMA node and MEMBLOCK_RSRV_KERN flag.

Please don't change the test. Just use MEMBLOCK_RSRV_KERN for the first
reserved region.

The same comment applies to other changes as well.

>   */
>  static int alloc_exact_nid_numa_reserved_full_merge_generic_check(void)
>  {
>  	int nid_req = 6;
>  	int nid_next = nid_req + 1;
> -	struct memblock_region *new_rgn = &memblock.reserved.regions[0];
> +	struct memblock_region *left_rgn = &memblock.reserved.regions[0];
> +	struct memblock_region *new_rgn = &memblock.reserved.regions[1];
> +	struct memblock_region *right_rgn = &memblock.reserved.regions[2];

-- 
Sincerely yours,
Mike.