Re: [PATCH v3] mm, slub: change run-time assertion in kmalloc_index() to compile-time

From: Hyeonggon Yoo <42.hyeyoo@gmail.com>
To: Nathan Chancellor <nathan@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>,
	akpm@linux-foundation.org, iamjoonsoo.kim@lge.com,
	rientjes@google.com, penberg@kernel.org, cl@linux.com,
	linux-mm@kvack.org, linux-kernel@vger.kernel.org,
	naresh.kamboju@linaro.org, clang-built-linux@googlegroups.com,
	linux-next@vger.kernel.org, ndesaulniers@google.com,
	lkft-triage@lists.linaro.org, sfr@canb.auug.org.au,
	arnd@arndb.de, Marco Elver <elver@google.com>
Subject: Re: [PATCH v3] mm, slub: change run-time assertion in kmalloc_index() to compile-time
Date: Tue, 18 May 2021 09:38:59 +0900	[thread overview]
Message-ID: <20210518003859.GC80297@hyeyoo> (raw)
In-Reply-To: <YKC9CeAfw3aBmHTU@archlinux-ax161>

On Sat, May 15, 2021 at 11:34:49PM -0700, Nathan Chancellor wrote:
> This should work I think:

compiled well with clang-10.0.1, clang-11.0.0,
and gcc-10.2.0 with x86_64 default config.

is the condition CONFIG_CLANG_VERSION > 110000,
not including 110000 it self?

> diff --git a/include/linux/slab.h b/include/linux/slab.h
> index 9d316aac0aba..1b653266f2aa 100644
> --- a/include/linux/slab.h
> +++ b/include/linux/slab.h
> @@ -413,7 +413,7 @@ static __always_inline unsigned int __kmalloc_index(size_t size,
>  	if (size <=  16 * 1024 * 1024) return 24;
>  	if (size <=  32 * 1024 * 1024) return 25;
>  
> -	if (size_is_constant)
> +	if ((IS_ENABLED(CONFIG_CC_IS_GCC) || CONFIG_CLANG_VERSION > 110000) && size_is_constant)
>  		BUILD_BUG_ON_MSG(1, "unexpected size in kmalloc_index()");
>  	else
>  		BUG();