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References: <cover.1640036051.git.andreyknvl@google.com> <dea9eb126793544650ff433612016016070ceb52.1640036051.git.andreyknvl@google.com>
 <YcHEjERoiqJTKmsZ@elver.google.com>
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From:   Andrey Konovalov <andreyknvl@gmail.com>
Date:   Thu, 30 Dec 2021 20:11:35 +0100
Message-ID: <CA+fCnZdk1gksiMMJVMe-fb56_4ZFUaaOLa4EZx0RCSR-3xd4AQ@mail.gmail.com>
Subject: Re: [PATCH mm v4 29/39] kasan, page_alloc: allow skipping memory init
 for HW_TAGS
To:     Marco Elver <elver@google.com>
Cc:     andrey.konovalov@linux.dev,
        Alexander Potapenko <glider@google.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Dmitry Vyukov <dvyukov@google.com>,
        Andrey Ryabinin <ryabinin.a.a@gmail.com>,
        kasan-dev <kasan-dev@googlegroups.com>,
        Linux Memory Management List <linux-mm@kvack.org>,
        Vincenzo Frascino <vincenzo.frascino@arm.com>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Will Deacon <will@kernel.org>,
        Mark Rutland <mark.rutland@arm.com>,
        Linux ARM <linux-arm-kernel@lists.infradead.org>,
        Peter Collingbourne <pcc@google.com>,
        Evgenii Stepanov <eugenis@google.com>,
        LKML <linux-kernel@vger.kernel.org>,
        Andrey Konovalov <andreyknvl@google.com>
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On Tue, Dec 21, 2021 at 1:12 PM Marco Elver <elver@google.com> wrote:
>
> On Mon, Dec 20, 2021 at 11:02PM +0100, andrey.konovalov@linux.dev wrote:
> > From: Andrey Konovalov <andreyknvl@google.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?

It is. I wanted to include those checks for completeness, but maybe
they just cause confusion instead. Will drop them in v5. Thanks!