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From: Linus Walleij <linus.walleij@linaro.org>
To: kernel test robot <lkp@intel.com>
Cc: kbuild-all@lists.01.org,
	Linux Memory Management List <linux-mm@kvack.org>,
	 Russell King <rmk+kernel@armlinux.org.uk>,
	Ard Biesheuvel <ardb@kernel.org>,
	 Abbott Liu <liuwenliang@huawei.com>,
	Florian Fainelli <f.fainelli@gmail.com>,
	 Linux ARM <linux-arm-kernel@lists.infradead.org>
Subject: Re: [linux-next:master 1570/2472] mm/kasan/init.c:318:9: warning: variable 'pud' set but not used
Date: Tue, 3 Nov 2020 01:17:35 +0100	[thread overview]
Message-ID: <CACRpkdZWS6UbCr-2+7F-BZQZOgjSzxjhyDTOW0vfm3Z3B5ys=g@mail.gmail.com> (raw)
In-Reply-To: <202011020749.5XQ3Hfzc-lkp@intel.com>

On Mon, Nov 2, 2020 at 12:32 AM kernel test robot <lkp@intel.com> wrote:

>    mm/kasan/init.c: In function 'kasan_free_pud':
> >> mm/kasan/init.c:318:9: warning: variable 'pud' set but not used [-Wunused-but-set-variable]
>      318 |  pud_t *pud;
>          |         ^~~

So this is because
arch/arm/include/asm/pgtable-2level.h has:
#define pud_none(pud)           (0)
because of the way that PMDs are folded into the PUD.
(See the comment in the file.)

This is not liked by KASan because it looks like the pud
variable is unused.

Any suggestions? Should it be:
#define pud_none(pud)          (!pud_val(pud))
Like most other archs?

I also toyed with just putting __maybe_unused into the kasan init.

Any other ways to solve this?

Yours,
Linus Walleij


  reply	other threads:[~2020-11-03  0:17 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-11-01 23:31 [linux-next:master 1570/2472] mm/kasan/init.c:318:9: warning: variable 'pud' set but not used kernel test robot
2020-11-03  0:17 ` Linus Walleij [this message]
2020-11-03  8:22   ` Ard Biesheuvel
2020-11-06  8:53     ` Linus Walleij

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