From owner-freebsd-bugs@freebsd.org Fri Nov 23 21:23:01 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 6DF3B11043EB for ; Fri, 23 Nov 2018 21:23:01 +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 F04DD75A08 for ; Fri, 23 Nov 2018 21:23:00 +0000 (UTC) (envelope-from bugzilla-noreply@freebsd.org) Received: by mailman.ysv.freebsd.org (Postfix) id B2A1511043EA; Fri, 23 Nov 2018 21:23:00 +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 A0D9F11043E8 for ; Fri, 23 Nov 2018 21:23:00 +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 2E0A875A05 for ; Fri, 23 Nov 2018 21:23:00 +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 611E71BC1E for ; Fri, 23 Nov 2018 21:22:59 +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 wANLMxA9074404 for ; Fri, 23 Nov 2018 21:22:59 GMT (envelope-from bugzilla-noreply@freebsd.org) Received: (from www@localhost) by kenobi.freebsd.org (8.15.2/8.15.2/Submit) id wANLMxD6074395 for bugs@FreeBSD.org; Fri, 23 Nov 2018 21:22:59 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 228858] panic when delivering knote to a process who has opened a kqueue() is dying Date: Fri, 23 Nov 2018 21:22:59 +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: 11.0-STABLE X-Bugzilla-Keywords: panic X-Bugzilla-Severity: Affects Some People X-Bugzilla-Who: markj@FreeBSD.org X-Bugzilla-Status: In Progress X-Bugzilla-Resolution: X-Bugzilla-Priority: --- X-Bugzilla-Assigned-To: markj@FreeBSD.org X-Bugzilla-Flags: X-Bugzilla-Changed-Fields: assigned_to bug_status 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-Rspamd-Queue-Id: F04DD75A08 X-Spamd-Result: default: False [1.69 / 15.00]; local_wl_from(0.00)[freebsd.org]; NEURAL_SPAM_LONG(0.42)[0.416,0]; NEURAL_SPAM_MEDIUM(0.75)[0.749,0]; ASN(0.00)[asn:10310, ipnet:2001:1900:2254::/48, country:US]; NEURAL_SPAM_SHORT(0.52)[0.523,0] X-Rspamd-Server: mx1.freebsd.org 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: Fri, 23 Nov 2018 21:23:01 -0000 https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D228858 Mark Johnston changed: What |Removed |Added ---------------------------------------------------------------------------- Assignee|bugs@FreeBSD.org |markj@FreeBSD.org Status|New |In Progress --- Comment #2 from Mark Johnston --- The process closing the kqueue should drain all of the kqueue's notes; this happens in kqueue_drain(). Unfortunately, we have a few races: - kqueue_register() doesn't check for KQ_CLOSING, so it may add knotes to t= he fdtable or hash table after we've started draining. This can be triggered = by knote_fork(). - The locking in knote_fork() is wrong: at the end of the loop we should be acquiring the list lock before the kqueue lock. Otherwise there's a window where the knote is unlocked and not in flux, and thus may be freed. To fix this I believe it's sufficient to just reorder the locking; the list lock c= omes before the kqueue lock in the lock order. The in-flux state of the knote is sufficient to prevent it from being removed, I believe, so we don't need a marker knote to hold our place in the list. --=20 You are receiving this mail because: You are the assignee for the bug.=