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| author | Peter Collingbourne <pcc@google.com> | 2022-05-09 18:20:53 -0700 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2022-05-13 07:20:07 -0700 |
| commit | d949a8155d139aa890795b802004a196b7f00598 (patch) | |
| tree | f4f44a8b94c40c132e6832035a8cd3a43adcc5e1 /include/linux/slab.h | |
| parent | 534aa1dc975ac883ad89110534585a96630802a0 (diff) | |
| download | linux-d949a8155d139aa890795b802004a196b7f00598.tar.gz linux-d949a8155d139aa890795b802004a196b7f00598.tar.bz2 linux-d949a8155d139aa890795b802004a196b7f00598.zip | |
mm: make minimum slab alignment a runtime property
When CONFIG_KASAN_HW_TAGS is enabled we currently increase the minimum
slab alignment to 16. This happens even if MTE is not supported in
hardware or disabled via kasan=off, which creates an unnecessary memory
overhead in those cases. Eliminate this overhead by making the minimum
slab alignment a runtime property and only aligning to 16 if KASAN is
enabled at runtime.
On a DragonBoard 845c (non-MTE hardware) with a kernel built with
CONFIG_KASAN_HW_TAGS, waiting for quiescence after a full Android boot I
see the following Slab measurements in /proc/meminfo (median of 3
reboots):
Before: 169020 kB
After: 167304 kB
[akpm@linux-foundation.org: make slab alignment type `unsigned int' to avoid casting]
Link: https://linux-review.googlesource.com/id/I752e725179b43b144153f4b6f584ceb646473ead
Link: https://lkml.kernel.org/r/20220427195820.1716975-2-pcc@google.com
Signed-off-by: Peter Collingbourne <pcc@google.com>
Reviewed-by: Andrey Konovalov <andreyknvl@gmail.com>
Reviewed-by: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Tested-by: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Acked-by: David Rientjes <rientjes@google.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Kees Cook <keescook@chromium.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'include/linux/slab.h')
| -rw-r--r-- | include/linux/slab.h | 12 |
1 files changed, 12 insertions, 0 deletions
diff --git a/include/linux/slab.h b/include/linux/slab.h index 373b3ef99f4e..3d2f2a3ca17e 100644 --- a/include/linux/slab.h +++ b/include/linux/slab.h @@ -210,6 +210,18 @@ void kmem_dump_obj(void *object); #endif /* + * Arches can define this function if they want to decide the minimum slab + * alignment at runtime. The value returned by the function must be a power + * of two and >= ARCH_SLAB_MINALIGN. + */ +#ifndef arch_slab_minalign +static inline unsigned int arch_slab_minalign(void) +{ + return ARCH_SLAB_MINALIGN; +} +#endif + +/* * kmalloc and friends return ARCH_KMALLOC_MINALIGN aligned * pointers. kmem_cache_alloc and friends return ARCH_SLAB_MINALIGN * aligned pointers. |