diff mbox series

[05/15] kfence: skip all GFP_ZONEMASK allocations

Message ID 20210723225014.XVYds8s7E%akpm@linux-foundation.org (mailing list archive)
State New
Headers show
Series [01/15] userfaultfd: do not untag user pointers | expand

Commit Message

Andrew Morton July 23, 2021, 10:50 p.m. UTC 
From: Alexander Potapenko <glider@google.com>
Subject: kfence: skip all GFP_ZONEMASK allocations

Allocation requests outside ZONE_NORMAL (MOVABLE, HIGHMEM or DMA) cannot
be fulfilled by KFENCE, because KFENCE memory pool is located in a zone
different from the requested one.

Because callers of kmem_cache_alloc() may actually rely on the allocation
to reside in the requested zone (e.g.  memory allocations done with
__GFP_DMA must be DMAable), skip all allocations done with GFP_ZONEMASK
and/or respective SLAB flags (SLAB_CACHE_DMA and SLAB_CACHE_DMA32).

Link: https://lkml.kernel.org/r/20210714092222.1890268-2-glider@google.com
Fixes: 0ce20dd84089 ("mm: add Kernel Electric-Fence infrastructure")
Signed-off-by: Alexander Potapenko <glider@google.com>
Reviewed-by: Marco Elver <elver@google.com>
Acked-by: Souptick Joarder <jrdr.linux@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Souptick Joarder <jrdr.linux@gmail.com>
Cc: <stable@vger.kernel.org>	[5.12+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/kfence/core.c |    9 +++++++++
 1 file changed, 9 insertions(+)
diff mbox series

Patch

--- a/mm/kfence/core.c~kfence-skip-all-gfp_zonemask-allocations
+++ a/mm/kfence/core.c
@@ -741,6 +741,15 @@  void *__kfence_alloc(struct kmem_cache *
 		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.