[PATCH 1/2] mm: Guard a use of node_reclaim_distance with CONFIFG_NUMA

From: Palmer Dabbelt
Date: Fri Feb 26 2021 - 15:28:59 EST


From: Palmer Dabbelt <palmerdabbelt@xxxxxxxxxx>

This is only useful under CONFIG_NUMA. IIUC skipping the check is the
right thing to do here, as without CONFIG_NUMA there will never be any
large node distances on non-NUMA systems.

I expected this to manifest as a link failure under (!CONFIG_NUMA &&
CONFIG_TRANSPARENT_HUGE_PAGES), but I'm not actually seeing that. I
think the reference is just getting pruned before it's checked, but I
didn't get that from reading the code so I'm worried I'm missing
something.

Either way, this is necessary to guard the definition of
node_reclaim_distance with CONFIG_NUMA.

Signed-off-by: Palmer Dabbelt <palmerdabbelt@xxxxxxxxxx>
---
mm/khugepaged.c | 2 ++
1 file changed, 2 insertions(+)

diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index a7d6cb912b05..b1bf191c3a54 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -819,8 +819,10 @@ static bool khugepaged_scan_abort(int nid)
for (i = 0; i < MAX_NUMNODES; i++) {
if (!khugepaged_node_load[i])
continue;
+#ifdef CONFIG_NUMA
if (node_distance(nid, i) > node_reclaim_distance)
return true;
+#endif
}
return false;
}
--
2.30.1.766.gb4fecdf3b7-goog