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From: Arnd Bergmann <arnd@arndb.de>
Date: Wed, 22 Mar 2017 15:13:00 +0100
Message-ID: <CAK8P3a2NdyBRciYh9_N0wq8B_u0uS+3HwiSqKYe5ez5uZdwkiQ@mail.gmail.com>
Subject: Re: [PATCH v2] x86: s/READ_ONCE_NOCHECK/READ_ONCE/ in arch_atomic[64]_read()
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Sender: owner-linux-mm@kvack.org
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To: Dmitry Vyukov <dvyukov@google.com>
Cc: Andrew Morton <akpm@linux-foundation.org>, Andrey Ryabinin <aryabinin@virtuozzo.com>, Mark Rutland <mark.rutland@arm.com>, Peter Zijlstra <peterz@infradead.org>, Will Deacon <will.deacon@arm.com>, Linux-MM <linux-mm@kvack.org>, x86@kernel.org, Linux Kernel Mailing List <linux-kernel@vger.kernel.org>, kasan-dev <kasan-dev@googlegroups.com>

On Wed, Mar 22, 2017 at 1:57 PM, Dmitry Vyukov <dvyukov@google.com> wrote:
> Two problems was reported with READ_ONCE_NOCHECK in arch_atomic_read:
> 1. Andrey Ryabinin reported significant binary size increase
> (+400K of text). READ_ONCE_NOCHECK is intentionally compiled to
> non-inlined function call, and I counted 640 copies of it in my vmlinux.
> 2. Arnd Bergmann reported a new splat of too large frame sizes.
>
> A single inlined KASAN check is very cheap, a non-inlined function
> call with KASAN/KCOV instrumentation can easily be more expensive.
>
> Switch to READ_ONCE() in arch_atomic[64]_read().
>
> Signed-off-by: Dmitry Vyukov <dvyukov@google.com>
> Reported-by: Arnd Bergmann <arnd@arndb.de>
> Reported-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
> Cc: Mark Rutland <mark.rutland@arm.com>
> Cc: Peter Zijlstra <peterz@infradead.org>
> Cc: Will Deacon <will.deacon@arm.com>
> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: linux-mm@kvack.org
> Cc: x86@kernel.org
> Cc: linux-kernel@vger.kernel.org
> Cc: kasan-dev@googlegroups.com
> Signed-off-by: Dmitry Vyukov <dvyukov@google.com>
>

Acked-by: Arnd Bergmann <arnd@arndb.de>

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