linux-kernel - Re: [PATCH mm v4 29/39] kasan, page_alloc: allow skipping memory init for HW

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Message-ID: <YcHEjERoiqJTKmsZ@elver.google.com>
Date:   Tue, 21 Dec 2021 13:11:56 +0100
From:   Marco Elver <elver@...gle.com>
To:     andrey.konovalov@...ux.dev
Cc:     Alexander Potapenko <glider@...gle.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Andrey Konovalov <andreyknvl@...il.com>,
        Dmitry Vyukov <dvyukov@...gle.com>,
        Andrey Ryabinin <ryabinin.a.a@...il.com>,
        kasan-dev@...glegroups.com, linux-mm@...ck.org,
        Vincenzo Frascino <vincenzo.frascino@....com>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        linux-arm-kernel@...ts.infradead.org,
        Peter Collingbourne <pcc@...gle.com>,
        Evgenii Stepanov <eugenis@...gle.com>,
        linux-kernel@...r.kernel.org,
        Andrey Konovalov <andreyknvl@...gle.com>
Subject: Re: [PATCH mm v4 29/39] kasan, page_alloc: allow skipping memory
 init for HW_TAGS

On Mon, Dec 20, 2021 at 11:02PM +0100, andrey.konovalov@...ux.dev wrote:
> From: Andrey Konovalov <andreyknvl@...gle.com>
[...]
> +static inline bool should_skip_init(gfp_t flags)
> +{
> +	/* Don't skip if a software KASAN mode is enabled. */
> +	if (IS_ENABLED(CONFIG_KASAN_GENERIC) ||
> +	    IS_ENABLED(CONFIG_KASAN_SW_TAGS))
> +		return false;
> +
> +	/* Don't skip, if hardware tag-based KASAN is not enabled. */
> +	if (!kasan_hw_tags_enabled())
> +		return false;

Why is the IS_ENABLED(CONFIG_KASAN_{GENERIC,SW_TAGS}) check above
required? Isn't kasan_hw_tags_enabled() always false if one of those is
configured?