From owner-freebsd-bugs@freebsd.org Tue Oct 30 17:09:55 2018 Return-Path: Delivered-To: freebsd-bugs@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id 1E09F10EE960 for ; Tue, 30 Oct 2018 17:09:55 +0000 (UTC) (envelope-from bugzilla-noreply@freebsd.org) Received: from mailman.ysv.freebsd.org (mailman.ysv.freebsd.org [IPv6:2001:1900:2254:206a::50:5]) by mx1.freebsd.org (Postfix) with ESMTP id AEA7A70102 for ; Tue, 30 Oct 2018 17:09:54 +0000 (UTC) (envelope-from bugzilla-noreply@freebsd.org) Received: by mailman.ysv.freebsd.org (Postfix) id 7377910EE95D; Tue, 30 Oct 2018 17:09:54 +0000 (UTC) Delivered-To: bugs@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id 6227010EE95C for ; Tue, 30 Oct 2018 17:09:54 +0000 (UTC) (envelope-from bugzilla-noreply@freebsd.org) Received: from mxrelay.ysv.freebsd.org (mxrelay.ysv.freebsd.org [IPv6:2001:1900:2254:206a::19:3]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits)) (Client CN "mxrelay.ysv.freebsd.org", Issuer "Let's Encrypt Authority X3" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 0456B700FF for ; Tue, 30 Oct 2018 17:09:54 +0000 (UTC) (envelope-from bugzilla-noreply@freebsd.org) Received: from kenobi.freebsd.org (kenobi.freebsd.org [IPv6:2001:1900:2254:206a::16:76]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by mxrelay.ysv.freebsd.org (Postfix) with ESMTPS id 3B32B16B8F for ; Tue, 30 Oct 2018 17:09:53 +0000 (UTC) (envelope-from bugzilla-noreply@freebsd.org) Received: from kenobi.freebsd.org ([127.0.1.118]) by kenobi.freebsd.org (8.15.2/8.15.2) with ESMTP id w9UH9rLg052772 for ; Tue, 30 Oct 2018 17:09:53 GMT (envelope-from bugzilla-noreply@freebsd.org) Received: (from www@localhost) by kenobi.freebsd.org (8.15.2/8.15.2/Submit) id w9UH9rcW052771 for bugs@FreeBSD.org; Tue, 30 Oct 2018 17:09:53 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 228768] EARLY_AP_STARTUP causes panic on amd machines Date: Tue, 30 Oct 2018 17:09:52 +0000 X-Bugzilla-Reason: AssignedTo X-Bugzilla-Type: changed X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: Base System X-Bugzilla-Component: kern X-Bugzilla-Version: CURRENT X-Bugzilla-Keywords: X-Bugzilla-Severity: Affects Only Me X-Bugzilla-Who: jhb@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: cc 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: 2.1.29 Precedence: list List-Id: Bug reports List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 30 Oct 2018 17:09:55 -0000 https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D228768 John Baldwin changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |kib@FreeBSD.org, | |mjg@FreeBSD.org --- Comment #4 from John Baldwin --- Oh, I think I have seen this once before. The issue is that the mtx_lock_spin() code tries to use DELAY(1) and DELAY() is trying to use the "clock_lock" in getit(). In your case, 'tsc_is_invariant' isn't true so DELAY() in sys/x86/x86/delay.c isn't using the TSC. I think the error is probably that we shouldn't be using DELAY(1) in our mu= tex code as it is too high level and/or we should special case DELAY(1) (vs DELAY(n)). Older versions of FreeBSD would map DELAY(1) to just 'inb(0x84)' without talking to the 8254 at all. It looks like i8254_delay() already do= es that when inside of KDB. Also, checking for tsc_is_invariant in DELAY is probably overly-correct. We aren't going to change P-states while we are spinning since we are actively spinning on the CPU. The worst that might happen is that if the CPU were running at a lower clock, we might wait too long. Given how DELAY is used, that's probably better than falling back to a slow timecounter with locks, = etc. --=20 You are receiving this mail because: You are the assignee for the bug.=