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Date:   Tue, 6 Jul 2021 12:49:01 +0300
From:   Andy Shevchenko <andy.shevchenko@gmail.com>
To:     Marco Elver <elver@google.com>
Cc:     Andrew Morton <akpm@linux-foundation.org>,
        Alexander Potapenko <glider@google.com>,
        Dmitry Vyukov <dvyukov@google.com>, pcc@google.com,
        Catalin Marinas <catalin.marinas@arm.com>,
        Vincenzo Frascino <vincenzo.frascino@arm.com>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        linux-mm <linux-mm@kvack.org>,
        kasan-dev <kasan-dev@googlegroups.com>,
        Andrey Ryabinin <ryabinin.a.a@gmail.com>,
        Andrey Konovalov <andreyknvl@gmail.com>
Subject: Re: [PATCH] kasan: fix build by including kernel.h
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On Mon, Jul 05, 2021 at 11:01:44AM +0200, Marco Elver wrote:
> On Mon, 5 Jul 2021 at 10:50, Andy Shevchenko <andy.shevchenko@gmail.com> wrote:
> > On Mon, Jul 5, 2021 at 10:28 AM Marco Elver <elver@google.com> wrote:
> > > The <linux/kasan.h> header relies on _RET_IP_ being defined, and had
> > > been receiving that definition via inclusion of bug.h which includes
> > > kernel.h. However, since f39650de687e that is no longer the case and get
> > > the following build error when building CONFIG_KASAN_HW_TAGS on arm64:
> > >
> > >   In file included from arch/arm64/mm/kasan_init.c:10:
> > >   ./include/linux/kasan.h: In function 'kasan_slab_free':
> > >   ./include/linux/kasan.h:230:39: error: '_RET_IP_' undeclared (first use in this function)
> > >     230 |   return __kasan_slab_free(s, object, _RET_IP_, init);
> > >
> > > Fix it by including kernel.h from kasan.h.
> >
> > ...which I would like to avoid in the long term, but for now it's
> > probably the best quick fix, otherwise it will require the real split
> > of _RET_IP or at least rethinking its location.
> >
> > Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.org>
> > Thanks!
> 
> Thanks!

Should be:
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>

> > > Fixes: f39650de687e ("kernel.h: split out panic and oops helpers")
> >
> > P.S. I have tested the initial patch against full build of x86_64, and
> > it was long time available for different CIs/build bots, none
> > complained so far.
> 
> It only manifests on arm64 when using CONFIG_KASAN_HW_TAGS mode
> (requires Arm64 MTE extensions). The other 2 modes include
> <linux/pgtable.h> in kasan.h, and that seems to include kernel.h
> somewhere. The HW_TAGS mode, however, doesn't receive -next testing by
> a CI system AFAIK, so this was missed because it's not yet used by
> many (I'd expect that to change when CPUs with MTE are more
> widespread).

Got it.

-- 
With Best Regards,
Andy Shevchenko