[PATCH] mm/vmscan: fix uninitialized variable in demote_folio_list()

[Bing Jiao <bingjiao@google.com>]

Commit d92027a5f30a6c ("mm/vmscan: select the closest preferred node in
demote_folio_list()") refactored the selection logic for demotion target
nodes. However, it removed the initial assignment of 'target_nid' while
leaving a premature check for 'NUMA_NO_NODE' in place.

Since 'target_nid' is now assigned further down in the function based on
preferred and allowed node masks, the initial check at line 1046 is
redundant.

Remove the redundant check to resolve the compiler warning.

Link: https://lkml.kernel.org/r/20260109055937.3739860-1-bingjiao@google.com
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202601091037.vUSHeJCH-lkp@intel.com/
Fixes: d92027a5f30a6c ("mm/vmscan: select the closest preferred node in demote_folio_list()")
Signed-off-by: Bing Jiao <bingjiao@google.com>
Reviewed-by: SeongJae Park <sj@kernel.org>
---

Hi Andrew,

Sorry for bother you again in my patch series.

There is a broken commit in mm-new branch, which is introduced by this
patch series, Commit d92027a5f30a6c ("mm/vmscan: select the closest
preferred node in demote_folio_list()").

As the broken commit is currently only in *mm-new*, could you please
squash the fix into the broken commit before it is pulled into
the mainline?

Thanks for your time!

Best regards,
Bing

---
 mm/vmscan.c | 4 ----
 1 file changed, 4 deletions(-)

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 213ee75b3306..590ab3ec1998 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1044,10 +1044,6 @@ static unsigned int demote_folio_list(struct list_head *demote_folios,
 	if (list_empty(demote_folios))
 		return 0;

-	if (target_nid == NUMA_NO_NODE)
-		/* No lower-tier nodes or nodes were hot-unplugged. */
-		return 0;
-
 	node_get_allowed_targets(pgdat, &allowed_mask);
 	mem_cgroup_node_filter_allowed(memcg, &allowed_mask);
 	if (nodes_empty(allowed_mask))
--
2.52.0.457.g6b5491de43-goog