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[84.3.50.134]) by smtp.gmail.com with ESMTPSA id bz14sm665571ejc.88.2020.07.24.06.28.04 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 24 Jul 2020 06:28:04 -0700 (PDT) Date: Fri, 24 Jul 2020 15:28:02 +0200 From: Ingo Molnar To: Joerg Roedel Cc: Thomas Gleixner , x86@kernel.org, Peter Zijlstra , Arnaldo Carvalho de Melo , Andy Lutomirski , Dave Hansen , linux-kernel@vger.kernel.org Subject: Re: Regression on todays tip/master (commit 16f70beccf43) Message-ID: <20200724132802.GA640628@gmail.com> References: <20200723133743.GA30716@8bytes.org> <871rl2xpar.fsf@nanos.tec.linutronix.de> <20200723145219.GP27672@8bytes.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200723145219.GP27672@8bytes.org> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Joerg Roedel wrote: > On Thu, Jul 23, 2020 at 04:46:04PM +0200, Thomas Gleixner wrote: > > Joerg Roedel writes: > > > while testing the SEV-ES patches on todays tip/master I triggered the BUG > > > below: > > > > > > [ 137.629660] ------------[ cut here ]------------ > > > [ 137.630769] kernel BUG at kernel/signal.c:1917! > > > [ 137.631796] invalid opcode: 0000 [#1] SMP NOPTI > > > [ 137.632822] CPU: 3 PID: 28596 Comm: test_syscall_vd Not tainted 5.8.0-rc6-tip+ #3 > > > [ 137.634495] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015 > > > [ 137.636236] RIP: 0010:do_notify_parent+0x25c/0x290 > > > The guest had 4 VCPUs and ran 4 instances of the in-kernel x86-selftests > > > in a loop, together with 'perf top -e cycles:k'. As you can see in the > > > time-stamps, the issue triggered pretty quickly. > > > > > > Please let me know if you need more information or testing from my side. > > > > Any chance to bisect this? > > Yes, will try. I am currently testing plain -rc6, it seems to be fine. > Bisecting is next. Given that you are perf stress-testing the box, some recent perf commit would be the primary suspect - before doing a full bisect you might want to try current perf/core (2ac5413e5edc) and its upstream base: v5.8-rc3, to narrow it down. But in principle any other commit could be the cause as well, the assert suggests memory corruption - I don't think we changed anything in the signal code. Thanks, Ingo