From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,HK_RANDOM_FROM,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 121DAC433B4 for ; Tue, 11 May 2021 03:03:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E54E261469 for ; Tue, 11 May 2021 03:03:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229964AbhEKDEz (ORCPT ); Mon, 10 May 2021 23:04:55 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35618 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229736AbhEKDEy (ORCPT ); Mon, 10 May 2021 23:04:54 -0400 Received: from mail-pg1-x531.google.com (mail-pg1-x531.google.com [IPv6:2607:f8b0:4864:20::531]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4E830C061574 for ; Mon, 10 May 2021 20:03:49 -0700 (PDT) Received: by mail-pg1-x531.google.com with SMTP id s22so14740566pgk.6 for ; Mon, 10 May 2021 20:03:49 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=ZDmXg4/mFr8nEo1HcwOFLGcCWD9FSJhKIPyfBmQ2tHQ=; b=QOYCuBvjXc2TwsM8hl5FMeSRYIKC0ziDeouJIj+twlVTNDRnK34t0OFaYyRoaZ3Aj1 uWHohMqHmfXbN1FacVnhLSD4UWeqe98e8/0VhCHxKA3CPt/cB5VsG743LT8x1rt1rYMN 3fE7798kdebLz5rivkhiOsXuAv0+fZWmvq33p6oYOIgU+DzTUS5W9UpmU/FdcIOv/Dx1 uHbguGbGtLq3b481wcJ6YANByVMbgVdtnqBJPwPZzdSNU+Qen0kQfozgOQ+3tNzduGaJ pXr0w6jEwEu7rFQx6aXa0bhSfJT1RlR0vPf0v8O5fFesp1HuzWfL4TwxReISYJ6zSB/a uPzQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=ZDmXg4/mFr8nEo1HcwOFLGcCWD9FSJhKIPyfBmQ2tHQ=; b=FCFXjcMzCWUuJG0eyRvr+gRnsyD+CZDtqUwFLcJ3Q0O7DVe461DzAywrsiOlPHwtKZ lb3yAbO4Yrlg1g28Csz6yiX2uUv2dbwxNQsOLS2vmKDf4yy+ReOTlPUELkdakNGGr0jB G2c58OQfH/9b2WZLJmNoC0jLJ6/HPhyUyGY3sFB+OwIFAJnD966L1fHQ+Cn4mnSmEXUt qVMTB/f5FOzJEMM38pE+VCYqWX92D9AKLdN9+VnPnj9ZSM96f5BohDk2EizC2gwv0neO vrHpVJufAgMjaJGhUuVdzDAf2c9xH40T0Gq29B7psxQTMDXtuEfLbrosya0pJrGQG/ZD iSJQ== X-Gm-Message-State: AOAM533RvxnrF9xaClW1IdsCTFpYpnC6r7Hu8HCcyPDOGyXYXne826mH a2+OSn3/1EIE8Bms4AgOrdo= X-Google-Smtp-Source: ABdhPJyNuOQR82+mfoGzHANMYhlrLf7Dj3j+I0LB1Mrf+dIRKeyv++Qxs6BoCFjbgtcK9PHGovkjWQ== X-Received: by 2002:a63:e1d:: with SMTP id d29mr29331179pgl.175.1620702228975; Mon, 10 May 2021 20:03:48 -0700 (PDT) Received: from hyeyoo ([183.99.11.150]) by smtp.gmail.com with ESMTPSA id k21sm1642639pgb.56.2021.05.10.20.03.46 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 10 May 2021 20:03:48 -0700 (PDT) Date: Tue, 11 May 2021 12:03:43 +0900 From: Hyeonggon Yoo <42.hyeyoo@gmail.com> To: Matthew Wilcox Cc: Vlastimil Babka , cl@linux.com, penberg@kernel.org, rientjes@google.com, iamjoonsoo.kim@lge.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2] mm: kmalloc_index: make compiler break when size is not supported Message-ID: <20210511030343.GB98904@hyeyoo> References: <20210508221328.7338-1-42.hyeyoo@gmail.com> <20210510135857.GA3594@hyeyoo> <9d0ffe49-a2e2-6c81-377b-4c8d2147dff8@suse.cz> <20210510150230.GA74915@hyeyoo> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, May 10, 2021 at 04:44:09PM +0100, Matthew Wilcox wrote: > On Tue, May 11, 2021 at 12:02:30AM +0900, Hyeonggon Yoo wrote: > > @@ -382,8 +385,8 @@ static __always_inline unsigned int kmalloc_index(size_t size) > > if (size <= 8 * 1024 * 1024) return 23; > > if (size <= 16 * 1024 * 1024) return 24; > > if (size <= 32 * 1024 * 1024) return 25; > > - if (size <= 64 * 1024 * 1024) return 26; > > - BUG(); > > + > > + BUILD_BUG_ON_MSG(1, "unexpected size in kmalloc_index()"); > > we're being encouraged to use static_assert() these days. > https://en.cppreference.com/w/c/language/_Static_assert > can you tell me difference between static_assert and BUILD_BUG_ON? it seems that mm subsystem does not make use of it now.