From owner-freebsd-bugs@freebsd.org Mon Sep 7 06:34:34 2020 Return-Path: Delivered-To: freebsd-bugs@mailman.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.nyi.freebsd.org (Postfix) with ESMTP id 351433EAA75 for ; Mon, 7 Sep 2020 06:34:34 +0000 (UTC) (envelope-from bugzilla-noreply@freebsd.org) Received: from mailman.nyi.freebsd.org (mailman.nyi.freebsd.org [IPv6:2610:1c1:1:606c::50:13]) by mx1.freebsd.org (Postfix) with ESMTP id 4BlJRF6v8Xz3TY3 for ; Mon, 7 Sep 2020 06:34:33 +0000 (UTC) (envelope-from bugzilla-noreply@freebsd.org) Received: by mailman.nyi.freebsd.org (Postfix) id E28623EA9EA; Mon, 7 Sep 2020 06:34:33 +0000 (UTC) Delivered-To: bugs@mailman.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.nyi.freebsd.org (Postfix) with ESMTP id E1CE63EAD3B for ; Mon, 7 Sep 2020 06:34:33 +0000 (UTC) (envelope-from bugzilla-noreply@freebsd.org) Received: from mxrelay.nyi.freebsd.org (mxrelay.nyi.freebsd.org [IPv6:2610:1c1:1:606c::19:3]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256 client-signature RSA-PSS (4096 bits) client-digest SHA256) (Client CN "mxrelay.nyi.freebsd.org", Issuer "Let's Encrypt Authority X3" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 4BlJRF552dz3TbW for ; Mon, 7 Sep 2020 06:34:33 +0000 (UTC) (envelope-from bugzilla-noreply@freebsd.org) Received: from kenobi.freebsd.org (kenobi.freebsd.org [IPv6:2610:1c1:1:606c::50:1d]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (Client did not present a certificate) by mxrelay.nyi.freebsd.org (Postfix) with ESMTPS id 40DA61B705 for ; Mon, 7 Sep 2020 06:34:33 +0000 (UTC) (envelope-from bugzilla-noreply@freebsd.org) Received: from kenobi.freebsd.org ([127.0.1.5]) by kenobi.freebsd.org (8.15.2/8.15.2) with ESMTP id 0876YXQb077910 for ; Mon, 7 Sep 2020 06:34:33 GMT (envelope-from bugzilla-noreply@freebsd.org) Received: (from www@localhost) by kenobi.freebsd.org (8.15.2/8.15.2/Submit) id 0876YXs1077907 for bugs@FreeBSD.org; Mon, 7 Sep 2020 06:34:33 GMT (envelope-from bugzilla-noreply@freebsd.org) X-Authentication-Warning: kenobi.freebsd.org: www set sender to bugzilla-noreply@freebsd.org using -f From: bugzilla-noreply@freebsd.org To: bugs@FreeBSD.org Subject: [Bug 249149] panic: -CURRENT with KCSAN option -> panic: mtx_lock_spin: recursed on non-recursive mutex et_hw_mtx @ src/sys/kern/kern_clocksource.c:850 Date: Mon, 07 Sep 2020 06:34:33 +0000 X-Bugzilla-Reason: AssignedTo X-Bugzilla-Type: changed X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: Base System X-Bugzilla-Component: bin X-Bugzilla-Version: CURRENT X-Bugzilla-Keywords: panic X-Bugzilla-Severity: Affects Some People X-Bugzilla-Who: jah@FreeBSD.org X-Bugzilla-Status: New X-Bugzilla-Resolution: X-Bugzilla-Priority: --- X-Bugzilla-Assigned-To: bugs@FreeBSD.org X-Bugzilla-Flags: X-Bugzilla-Changed-Fields: Message-ID: In-Reply-To: References: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Bugzilla-URL: https://bugs.freebsd.org/bugzilla/ Auto-Submitted: auto-generated MIME-Version: 1.0 X-BeenThere: freebsd-bugs@freebsd.org X-Mailman-Version: 2.1.33 Precedence: list List-Id: Bug reports List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 07 Sep 2020 06:34:34 -0000 https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D249149 --- Comment #2 from Jason A. Harmening --- It looks like this is a KCSan false positive on the LAPIC MMIO mapping. Si= nce this is a guest that doesn't use the x2APIC (and therefore must use MMIO for LAPIC access instead of MSRs), all CPUs will share the same LAPIC mapping.= =20 However, the underlying physical access will be routed to the local CPU's A= PIC, so multiple CPUs aren't actually racing on the same hardware resource. Or= at least I hope that's the source of the problem, otherwise Hyper-V really misconfigured the guest. Since the LAPIC access happens in the course of configuring an event timer,= and the KCSan warning printf itself tries to configure a callout, we get the pa= nic. Can you try the attached (build-tested only) patch? --=20 You are receiving this mail because: You are the assignee for the bug.=