| Message ID | 20210630135313.1072577-2-glider@google.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | [v3,1/2] kfence: move the size check to the beginning of __kfence_alloc() | expand |
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 >
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). + */ + 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
Allocation requests outside ZONE_NORMAL (MOVABLE, HIGHMEM or DNA) 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). 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> --- 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(+)