[RFC v2 4/4] mm: fallback for offline nodes in alloc_pages_node

From: Vlastimil Babka <vbabka@suse.cz>
To: linux-mm@kvack.org
Cc: linux-kernel@vger.kernel.org,
	Andrew Morton <akpm@linux-foundation.org>,
	Mel Gorman <mgorman@suse.de>,
	David Rientjes <rientjes@google.com>,
	Greg Thelen <gthelen@google.com>,
	"Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>,
	Christoph Lameter <cl@linux.com>,
	Pekka Enberg <penberg@kernel.org>,
	Joonsoo Kim <iamjoonsoo.kim@lge.com>,
	Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>,
	Vlastimil Babka <vbabka@suse.cz>
Subject: [RFC v2 4/4] mm: fallback for offline nodes in alloc_pages_node
Date: Fri, 24 Jul 2015 16:45:26 +0200	[thread overview]
Message-ID: <1437749126-25867-4-git-send-email-vbabka@suse.cz> (raw)
In-Reply-To: <1437749126-25867-1-git-send-email-vbabka@suse.cz>

alloc_pages_node() now warns when an offline node is passed. Make it fallback
to the local (or nearest) node as if NUMA_NO_NODE nid is passed, but keep the
VM_WARN_ON warning.

Suggested-by: David Rientjes <rientjes@google.com>
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
---
David's suggested if(VM_WARN_ON(...)) doesn't work that way, hence this more
involved and awkward syntax.

 include/linux/gfp.h | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/include/linux/gfp.h b/include/linux/gfp.h
index 531c72d..104a027 100644
--- a/include/linux/gfp.h
+++ b/include/linux/gfp.h
@@ -321,8 +321,12 @@ static inline struct page *alloc_pages_node(int nid, gfp_t gfp_mask,
 						unsigned int order)
 {
 	/* Unknown node is current (or closest) node */
-	if (nid == NUMA_NO_NODE)
+	if (nid == NUMA_NO_NODE) {
 		nid = numa_mem_id();
+	} else if (!node_online(nid)) {
+		VM_WARN_ON(!node_online(nid));
+		nid = numa_mem_id();
+	}
 
 	return __alloc_pages_node(nid, gfp_mask, order);
 }
-- 
2.4.6

