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-rw-r--r--mm/kfence/core.c19
1 files changed, 16 insertions, 3 deletions
diff --git a/mm/kfence/core.c b/mm/kfence/core.c
index d7666ace9d2e..575c685aa642 100644
--- a/mm/kfence/core.c
+++ b/mm/kfence/core.c
@@ -734,6 +734,22 @@ void kfence_shutdown_cache(struct kmem_cache *s)
void *__kfence_alloc(struct kmem_cache *s, size_t size, gfp_t flags)
{
/*
+ * Perform size check before switching kfence_allocation_gate, so that
+ * we don't disable KFENCE without making an allocation.
+ */
+ if (size > PAGE_SIZE)
+ return NULL;
+
+ /*
+ * Skip allocations from non-default zones, including DMA. We cannot
+ * guarantee that pages in the KFENCE pool will have the requested
+ * properties (e.g. reside in DMAable memory).
+ */
+ if ((flags & GFP_ZONEMASK) ||
+ (s->flags & (SLAB_CACHE_DMA | SLAB_CACHE_DMA32)))
+ return NULL;
+
+ /*
* allocation_gate only needs to become non-zero, so it doesn't make
* sense to continue writing to it and pay the associated contention
* cost, in case we have a large number of concurrent allocations.
@@ -757,9 +773,6 @@ void *__kfence_alloc(struct kmem_cache *s, size_t size, gfp_t flags)
if (!READ_ONCE(kfence_enabled))
return NULL;
- if (size > PAGE_SIZE)
- return NULL;
-
return kfence_guarded_alloc(s, size, flags);
}