Re: [PATCH v3] mm: make minimum slab alignment a runtime property

From: Catalin Marinas
Date: Mon Apr 25 2022 - 11:56:18 EST

On Fri, Apr 22, 2022 at 01:18:30PM -0700, Peter Collingbourne wrote:
> 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
> Link:
> Signed-off-by: Peter Collingbourne <pcc@xxxxxxxxxx>
> Reviewed-by: Andrey Konovalov <andreyknvl@xxxxxxxxx>

Reviewed-by: Catalin Marinas <catalin.marinas@xxxxxxx>