kfence: skip __GFP_THISNODE allocations on NUMA systems

commit e64f819
Author: Marco Elver <[email protected]>
Date:   Fri Jan 24 13:01:38 2025 +0100

    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.

    Link: https://lkml.kernel.org/r/[email protected]
    Fixes: 236e9f1 ("kfence: skip all GFP_ZONEMASK allocations")
    Signed-off-by: Marco Elver <[email protected]>
    Reported-by: Vlastimil Babka <[email protected]>
    Acked-by: Vlastimil Babka <[email protected]>
    Cc: Christoph Lameter <[email protected]>
    Cc: Alexander Potapenko <[email protected]>
    Cc: Chistoph Lameter <[email protected]>
    Cc: Dmitriy Vyukov <[email protected]>
    Cc: <[email protected]>
    Signed-off-by: Andrew Morton <[email protected]>

JIRA: https://issues.redhat.com/browse/RHEL-77742
Signed-off-by: Nico Pache <[email protected]>

Author: PacheNico

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;