linux-kernel - [PATCH] kfence: skip __GFP_THISNODE allocations on NUMA systems

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Message-ID: <20250124120145.410066-1-elver@google.com>
Date: Fri, 24 Jan 2025 13:01:38 +0100
From: Marco Elver <elver@...gle.com>
To: elver@...gle.com, Andrew Morton <akpm@...ux-foundation.org>
Cc: Alexander Potapenko <glider@...gle.com>, Dmitry Vyukov <dvyukov@...gle.com>, kasan-dev@...glegroups.com, 
	linux-mm@...ck.org, linux-kernel@...r.kernel.org, 
	Vlastimil Babka <vbabka@...e.cz>, Christoph Lameter <cl@...ux.com>
Subject: [PATCH] kfence: skip __GFP_THISNODE allocations on NUMA systems

On NUMA systems, __GFP_THISNODE indicates that an allocation _must_ be
on a particular node, and failure to allocate on the desired node will
result in a failed allocation.

Skip __GFP_THISNODE allocations if we are running on a NUMA system,
since KFENCE can't guarantee which node its pool pages are allocated on.

Reported-by: Vlastimil Babka <vbabka@...e.cz>
Cc: Christoph Lameter <cl@...ux.com>
Fixes: 236e9f153852 ("kfence: skip all GFP_ZONEMASK allocations")
Signed-off-by: Marco Elver <elver@...gle.com>
---
 mm/kfence/core.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/mm/kfence/core.c b/mm/kfence/core.c
index 67fc321db79b..102048821c22 100644
--- a/mm/kfence/core.c
+++ b/mm/kfence/core.c
@@ -21,6 +21,7 @@
 #include <linux/log2.h>
 #include <linux/memblock.h>
 #include <linux/moduleparam.h>
+#include <linux/nodemask.h>
 #include <linux/notifier.h>
 #include <linux/panic_notifier.h>
 #include <linux/random.h>
@@ -1084,6 +1085,7 @@ void *__kfence_alloc(struct kmem_cache *s, size_t size, gfp_t flags)
 	 * properties (e.g. reside in DMAable memory).
 	 */
 	if ((flags & GFP_ZONEMASK) ||
+	    ((flags & __GFP_THISNODE) && num_online_nodes() > 1) ||
 	    (s->flags & (SLAB_CACHE_DMA | SLAB_CACHE_DMA32))) {
 		atomic_long_inc(&counters[KFENCE_COUNTER_SKIP_INCOMPAT]);
 		return NULL;
-- 
2.48.1.262.g85cc9f2d1e-goog