[RFC PATCH 1/2] mm/fake-numa: fix under-allocation detection logic in uniform split

[Sang-Heon Jeon <ekffu200098@gmail.com>]

When split NUMA node uniformly, split_nodes_size_interleave_uniform()
returns the next absolute node ID, not the number of nodes created.

The previous under-allocation detection logic compares next absolute node
ID (ret) and request count (n), which only works when nid starts at 0.

Fix under-allocation detection logic to compare the number of actually
created nodes (ret - nid) against the request count (n).

Signed-off-by: Sang-Heon Jeon <ekffu200098@gmail.com>
Reported-by: Donghyeon Lee <asd142513@gmail.com>
Reported-by: Munhui Chae <mochae@student.42seoul.kr>
Fixes: cc9aec03e58f ("x86/numa_emulation: Introduce uniform split capability") # 4.19
---
 mm/numa_emulation.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/numa_emulation.c b/mm/numa_emulation.c
index 703c8fa05048..e7f856c8f2a1 100644
--- a/mm/numa_emulation.c
+++ b/mm/numa_emulation.c
@@ -416,7 +416,7 @@ void __init numa_emulation(struct numa_meminfo *numa_meminfo, int numa_dist_cnt)
 					n, &pi.blk[0], nid);
 			if (ret < 0)
 				break;
-			if (ret < n) {
+			if (ret - nid < n) {
 				pr_info("%s: phys: %d only got %d of %ld nodes, failing\n",
 						__func__, i, ret, n);
 				ret = -1;
-- 
2.43.0