On Wed, 30 Jun 2021 at 15:53, Alexander Potapenko glider@google.com wrote:
Allocation requests outside ZONE_NORMAL (MOVABLE, HIGHMEM or DNA) cannot
s/DNA/DMA/ ... but probably no need to do v4 just for this (everyone knows we're not yet in the business of allocating DNA ;-)).
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).
Fixes: 0ce20dd84089 ("mm: add Kernel Electric-Fence infrastructure") Cc: Andrew Morton akpm@linux-foundation.org Cc: Dmitry Vyukov dvyukov@google.com Cc: Marco Elver elver@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: Alexander Potapenko glider@google.com
With the change below, you can add:
Reviewed-by: Marco Elver elver@google.com
v2:
- added parentheses around the GFP clause, as requested by Marco
v3:
- ignore GFP_ZONEMASK, which also covers __GFP_HIGHMEM and __GFP_MOVABLE
- move the flag check at the beginning of the function, as requested by Souptick Joarder
mm/kfence/core.c | 8 ++++++++ 1 file changed, 8 insertions(+)
diff --git a/mm/kfence/core.c b/mm/kfence/core.c index 33bb20d91bf6a..d51f77329fd3c 100644 --- a/mm/kfence/core.c +++ b/mm/kfence/core.c @@ -740,6 +740,14 @@ void *__kfence_alloc(struct kmem_cache *s, size_t size, gfp_t flags) 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).
Comments should still be 80 cols, like the rest of the file. :-/
*/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-- 2.32.0.93.g670b81a890-goog