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=-0.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS 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 3C5B6C35246 for ; Tue, 28 Jan 2020 07:33:59 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 021A722522 for ; Tue, 28 Jan 2020 07:33:58 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=linaro.org header.i=@linaro.org header.b="dwotw4Ka" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 021A722522 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linaro.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 7C8786B0008; Tue, 28 Jan 2020 02:33:58 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 751CB6B000A; Tue, 28 Jan 2020 02:33:58 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 619FF6B000C; Tue, 28 Jan 2020 02:33:58 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0205.hostedemail.com [216.40.44.205]) by kanga.kvack.org (Postfix) with ESMTP id 47BA36B0008 for ; Tue, 28 Jan 2020 02:33:58 -0500 (EST) Received: from smtpin28.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with SMTP id EF7F9180AD802 for ; Tue, 28 Jan 2020 07:33:57 +0000 (UTC) X-FDA: 76426228914.28.crime14_79de16c70784e X-HE-Tag: crime14_79de16c70784e X-Filterd-Recvd-Size: 4605 Received: from mail-wr1-f66.google.com (mail-wr1-f66.google.com [209.85.221.66]) by imf10.hostedemail.com (Postfix) with ESMTP for ; Tue, 28 Jan 2020 07:33:57 +0000 (UTC) Received: by mail-wr1-f66.google.com with SMTP id y17so14765409wrh.5 for ; Mon, 27 Jan 2020 23:33:57 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=M8/h2bPEqPWeThJEypD1fDrIV3uZkJ0Spf9SsxFALTw=; b=dwotw4KanF7Rr5R8R+2zrC3GotxW2umZNPfukUzk39baBmVods+BoK4dMAq69uYY7g w+SGWEGZHNJ117MWwkKscB+LUpFA0VTRNzPK5XqDaJvKe5Qj2nkaCcDoJ37jygI6Qko+ TrLELDx6JWBc5d4RGGgNhVk054IOYJNs7Gz1W+rYkqSELCoMtxiqUTLaa+Ua/RvykWui fB3lw5IUXN6sGkdbULostObMmmUdEVueFtG0ZIY2lKIFB1p2LE2rZw9EW/wnf5Kug4nS MGe6fZlyEvhDmlbzuJY2E+FIUkQkEF8t9chSY/c3eX8dC4ULgOQy+d2PN6O42rumfvFZ 6/mQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=M8/h2bPEqPWeThJEypD1fDrIV3uZkJ0Spf9SsxFALTw=; b=nn7sXD7EbtuRhpR9D5LFMiNsewlF7iYlehx0DL7pd+0CEb8mjGRpljzNHVKbNnaN4g AEPjCsYUUfWx0E2gpgmLT0GDyEMpZ+c1zCR9KYjgx6YJ19JGJlsEQjsdlPJPXkLGuJyE vLD7FtM6j7Py5vIBLlzIM01DBq5k5/wSaaS17rB1xc8xNNyfkyplPML91t0dJNBY0W/e VBAhNoXtF4nds5z56kWRl2qS8KWRWBExwT8xcwZnfwFrU0+Zl4NcelCV9AfhAKyMzFdn KjTqPkjXkoN1skneBNQcHJeWTpC75jG4Ut2Gf21sSg/41r/BaRVxVOem2Ijr8ueK97u+ sZpQ== X-Gm-Message-State: APjAAAXO/jCb5cc39z3X5chpjEjubE+fLRmMxY0vhqHIZAOSkicYAJyt 45KYaZoS4lRpXTduoM1JEzJXG2xU4ND/JHTQndwNgQ== X-Google-Smtp-Source: APXvYqzRsFwG9bEQ85NBunD148AjHa0dxOfEOo4Rm/EgIgpxum6o/BtnVYQzHUFVAAdT5QZodGqW2WChnr5jeU+fLZs= X-Received: by 2002:a5d:65cf:: with SMTP id e15mr26280990wrw.126.1580196836110; Mon, 27 Jan 2020 23:33:56 -0800 (PST) MIME-Version: 1.0 References: In-Reply-To: From: Ard Biesheuvel Date: Tue, 28 Jan 2020 08:33:45 +0100 Message-ID: Subject: Re: mmotm 2020-01-23-21-12 uploaded (efi) To: Dmitry Vyukov Cc: Qian Cai , Randy Dunlap , Andrew Morton , Mark Brown , linux-fsdevel , Linux Kernel Mailing List , Linux-MM , Linux-Next Mailing List , Michal Hocko , mm-commits@vger.kernel.org, Stephen Rothwell , Ard Biesheuvel , linux-efi , kasan-dev Content-Type: text/plain; charset="UTF-8" X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Tue, 28 Jan 2020 at 07:26, Dmitry Vyukov wrote: > > On Tue, Jan 28, 2020 at 7:15 AM Qian Cai wrote: > > > Should be fixed by > > > > > > https://lore.kernel.org/linux-efi/20200121093912.5246-1-ardb@kernel.org/ > > > > Cc kasan-devel@ > > > > If everyone has to disable KASAN for the whole subdirectories like this, I am worried about we are losing testing coverage fairly quickly. Is there a bug in compiler? > > My understanding is that this is invalid C code in the first place, > no? It just happened to compile with some compilers, some options and > probably only with high optimization level. No, this is not true. The whole point of favoring IS_ENABLED(...) over #ifdef ... has always been that the code remains visible to the compiler, regardless of whether the option is selected or not, but that it gets optimized away entirely. The linker errors prove that there is dead code remaining in the object files, which means we can no longer rely on IS_ENABLED() to work as intended. > There is a known, simple fix that is used throughout the kernel - > provide empty static inline stub, or put whole calls under ifdef. No, sorry, that doesn't work for me. I think it is great that we have diagnostic features that are as powerful as KASAN, but if they require code changes beyond enable/disable, I am not going to rely on them.