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[66.187.233.206]) by smtp.gmail.com with ESMTPSA id w5sm10384776qkf.43.2019.11.19.11.02.49 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 19 Nov 2019 11:02:50 -0800 (PST) Message-ID: <1574190168.9585.4.camel@lca.pw> Subject: Re: linux-next: Tree for Nov 19 (kcsan) From: Qian Cai To: Marco Elver , Randy Dunlap Cc: Stephen Rothwell , Linux Next Mailing List , Linux Kernel Mailing List , kasan-dev , Dmitry Vyukov , "Paul E. McKenney" Date: Tue, 19 Nov 2019 14:02:48 -0500 In-Reply-To: <20191119183407.GA68739@google.com> References: <20191119194658.39af50d0@canb.auug.org.au> <20191119183407.GA68739@google.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.22.6 (3.22.6-10.el7) Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 2019-11-19 at 19:34 +0100, 'Marco Elver' via kasan-dev wrote: > On Tue, 19 Nov 2019, Randy Dunlap wrote: > > > On 11/19/19 8:12 AM, Marco Elver wrote: > > > On Tue, 19 Nov 2019 at 16:11, Randy Dunlap wrote: > > > > > > > > On 11/19/19 12:46 AM, Stephen Rothwell wrote: > > > > > Hi all, > > > > > > > > > > Changes since 20191118: > > > > > > > > > > > > > on x86_64: > > > > > > > > It seems that this function can already be known by the compiler as a > > > > builtin: > > > > > > > > ../kernel/kcsan/core.c:619:6: warning: conflicting types for built-in function ‘__tsan_func_exit’ [-Wbuiltin-declaration-mismatch] > > > > void __tsan_func_exit(void) > > > > ^~~~~~~~~~~~~~~~ > > > > > > > > > > > > $ gcc --version > > > > gcc (SUSE Linux) 7.4.1 20190905 [gcc-7-branch revision 275407] > > > > > > Interesting. Could you share the .config? So far I haven't been able > > > to reproduce. > > > > Sure, it's attached. > > Thanks, the config did the trick, even for gcc 9.0.0. > > The problem is CONFIG_UBSAN=y. We haven't explicitly disallowed it like > with KASAN. In principle there should be nothing wrong with KCSAN+UBSAN. > > There are 3 options: > 1. Just disable UBSAN for KCSAN, and also disable KCSAN for UBSAN. > 2. Restrict the config to not allow combining KCSAN and UBSAN. > 3. Leave things as-is. > > Option 1 probably makes most sense, and I'll send a patch for that > unless there are major objections. Both option #1 and #2 sounds quite unfortunate, as UBSAN is quite valuable for debugging. Hence, it is desire to make both work at the same time.