[RFC PATCH 1/2] include/linux/gfp.h: Do not allocate pages on a offlined node

[Nico Pache]

We shouldn't allocate pages on a unavailable node. Add a check for this
in __alloc_pages_node and return NULL to avoid issues further down the
callchain.

Also update the VM_WARN_ON in __alloc_pages_node which could skip this
warn if the gfp_mask is not GFP_THISNODE.

Co-developed-by: Rafael Aquini <aquini@xxxxxxxxxx>
Signed-off-by: Nico Pache <npache@xxxxxxxxxx>
---
 include/linux/gfp.h | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/include/linux/gfp.h b/include/linux/gfp.h
index b976c4177299..e7e18f6d0d9d 100644
--- a/include/linux/gfp.h
+++ b/include/linux/gfp.h
@@ -565,7 +565,10 @@ static inline struct page *
 __alloc_pages_node(int nid, gfp_t gfp_mask, unsigned int order)
 {
 	VM_BUG_ON(nid < 0 || nid >= MAX_NUMNODES);
-	VM_WARN_ON((gfp_mask & __GFP_THISNODE) && !node_online(nid));
+	VM_WARN_ON(!node_online(nid));
+
+	if (!node_online(nid))
+		return NULL;
 
 	return __alloc_pages(gfp_mask, order, nid, NULL);
 }
-- 
2.33.1