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Date:   Mon, 12 Apr 2021 09:15:15 +0100
From:   Catalin Marinas <catalin.marinas@arm.com>
To:     Andrew Morton <akpm@linux-foundation.org>
Cc:     Andrey Konovalov <andreyknvl@gmail.com>,
        Andrey Ryabinin <ryabinin.a.a@gmail.com>,
        Alexander Potapenko <glider@google.com>,
        Dmitry Vyukov <dvyukov@google.com>,
        Nathan Chancellor <natechancellor@gmail.com>,
        Arnd Bergmann <arnd@arndb.de>,
        kasan-dev <kasan-dev@googlegroups.com>,
        Linux Memory Management List <linux-mm@kvack.org>,
        LKML <linux-kernel@vger.kernel.org>,
        Linux ARM <linux-arm-kernel@lists.infradead.org>,
        wsd_upstream <wsd_upstream@mediatek.com>,
        "moderated list:ARM/Mediatek SoC..." 
        <linux-mediatek@lists.infradead.org>,
        Walter Wu <walter-zh.wu@mediatek.com>
Subject: Re: [PATCH v4] kasan: remove redundant config option
Message-ID: <20210412081515.GB2060@arm.com>
References: <20210226012531.29231-1-walter-zh.wu@mediatek.com>
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 <20210330223637.f3c73a78c64587e615d26766@linux-foundation.org>
 <20210411105332.GA23778@arm.com>
 <20210411150316.d60aa0b5174adf2370538809@linux-foundation.org>
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On Sun, Apr 11, 2021 at 03:03:16PM -0700, Andrew Morton wrote:
> On Sun, 11 Apr 2021 11:53:33 +0100 Catalin Marinas <catalin.marinas@arm.com> wrote:
> > On Tue, Mar 30, 2021 at 10:36:37PM -0700, Andrew Morton wrote:
> > > On Mon, 29 Mar 2021 16:54:26 +0200 Andrey Konovalov <andreyknvl@google.com> wrote:
> > > > Looks like my patch "kasan: fix KASAN_STACK dependency for HW_TAGS"
> > > > that was merged into 5.12-rc causes a build time warning:
> > > > 
> > > > include/linux/kasan.h:333:30: warning: 'CONFIG_KASAN_STACK' is not
> > > > defined, evaluates to 0 [-Wundef]
> > > > #if defined(CONFIG_KASAN) && CONFIG_KASAN_STACK
> > > > 
> > > > The fix for it would either be reverting the patch (which would leave
> > > > the initial issue unfixed) or applying this "kasan: remove redundant
> > > > config option" patch.
> > > > 
> > > > Would it be possible to send this patch (with the fix-up you have in
> > > > mm) for the next 5.12-rc?
> > > > 
> > > > Here are the required tags:
> > > > 
> > > > Fixes: d9b571c885a8 ("kasan: fix KASAN_STACK dependency for HW_TAGS")
> > > > Cc: stable@vger.kernel.org
> > > 
> > > Got it, thanks.  I updated the changelog to mention the warning fix and
> > > moved these ahead for a -rc merge.
> > 
> > Is there a chance this patch makes it into 5.12? I still get the warning
> > with the latest Linus' tree (v5.12-rc6-408-g52e44129fba5) when enabling
> > KASAN_HW_TAGS.
> 
> Trying.   We're still awaiting a tested fix for
> https://lkml.kernel.org/r/CA+fCnZf1ABrQg0dsxtoZa9zM1BSbLYq_Xbu+xi9cv8WAZxdC2g@mail.gmail.com

Thanks Andrew. I didn't realise it was sent and then dropped.

However, we should decouple (or rather reorder) the two patches. There's
no functional dependency between removing the redundant config option (a
fix for an existing commit) and adding support for KASAN_SW_TAGS with
gcc-11, only a conflict in scripts/Makefile.kasan. Walter's original
patch applies on top of vanilla 5.12-rc3:

https://lkml.kernel.org/r/20210226012531.29231-1-walter-zh.wu@mediatek.com

-- 
Catalin