From owner-svn-src-stable-8@freebsd.org Wed Feb 17 01:45:35 2016 Return-Path: Delivered-To: svn-src-stable-8@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id DF34FAAB9BC; Wed, 17 Feb 2016 01:45:35 +0000 (UTC) (envelope-from jhb@FreeBSD.org) Received: from repo.freebsd.org (repo.freebsd.org [IPv6:2610:1c1:1:6068::e6a:0]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id 8EA8D10FC; Wed, 17 Feb 2016 01:45:35 +0000 (UTC) (envelope-from jhb@FreeBSD.org) Received: from repo.freebsd.org ([127.0.1.37]) by repo.freebsd.org (8.15.2/8.15.2) with ESMTP id u1H1jY0v026737; Wed, 17 Feb 2016 01:45:34 GMT (envelope-from jhb@FreeBSD.org) Received: (from jhb@localhost) by repo.freebsd.org (8.15.2/8.15.2/Submit) id u1H1jY16026735; Wed, 17 Feb 2016 01:45:34 GMT (envelope-from jhb@FreeBSD.org) Message-Id: <201602170145.u1H1jY16026735@repo.freebsd.org> X-Authentication-Warning: repo.freebsd.org: jhb set sender to jhb@FreeBSD.org using -f From: John Baldwin Date: Wed, 17 Feb 2016 01:45:34 +0000 (UTC) To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-stable@freebsd.org, svn-src-stable-8@freebsd.org Subject: svn commit: r295684 - in stable: 8/sys/kern 9/sys/kern X-SVN-Group: stable-8 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-BeenThere: svn-src-stable-8@freebsd.org X-Mailman-Version: 2.1.20 Precedence: list List-Id: SVN commit messages for only the 8-stable src tree List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 17 Feb 2016 01:45:36 -0000 Author: jhb Date: Wed Feb 17 01:45:34 2016 New Revision: 295684 URL: https://svnweb.freebsd.org/changeset/base/295684 Log: MFC 295418,295419: Fix hangs or panics when misbehaved kernel threads return from their main function. 295418: Mark proc0 as a kernel process via the P_KTHREAD flag. All other kernel processes have this flag set and all threads in proc0 (including thread0) have the similar TDP_KTHREAD flag set. 295419: Call kthread_exit() rather than kproc_exit() for a premature kthread exit. Kernel threads (and processes) are supposed to call kthread_exit() (or kproc_exit()) to terminate. However, the kernel includes a fallback in fork_exit() to force a kthread exit if a kernel thread's "main" routine returns. This fallback was added back when the kernel only had processes and was not updated to call kthread_exit() instead of kproc_exit() when threads were added to the kernel. This mistake was particularly exciting when the errant thread belonged to proc0. Due to the missing P_KTHREAD flag the fallback did not kick in and instead tried to return to userland via whatever garbage was in the trapframe. With P_KTHREAD set it tried to terminate proc0 resulting in other amusements. PR: 204999 Modified: stable/8/sys/kern/init_main.c stable/8/sys/kern/kern_fork.c Directory Properties: stable/8/sys/ (props changed) stable/8/sys/kern/ (props changed) Changes in other areas also in this revision: Modified: stable/9/sys/kern/init_main.c stable/9/sys/kern/kern_fork.c Directory Properties: stable/9/sys/ (props changed) Modified: stable/8/sys/kern/init_main.c ============================================================================== --- stable/8/sys/kern/init_main.c Wed Feb 17 00:30:28 2016 (r295683) +++ stable/8/sys/kern/init_main.c Wed Feb 17 01:45:34 2016 (r295684) @@ -451,7 +451,7 @@ proc0_init(void *dummy __unused) session0.s_leader = p; p->p_sysent = &null_sysvec; - p->p_flag = P_SYSTEM | P_INMEM; + p->p_flag = P_SYSTEM | P_INMEM | P_KTHREAD; p->p_state = PRS_NORMAL; knlist_init_mtx(&p->p_klist, &p->p_mtx); STAILQ_INIT(&p->p_ktr); Modified: stable/8/sys/kern/kern_fork.c ============================================================================== --- stable/8/sys/kern/kern_fork.c Wed Feb 17 00:30:28 2016 (r295683) +++ stable/8/sys/kern/kern_fork.c Wed Feb 17 01:45:34 2016 (r295684) @@ -878,7 +878,7 @@ fork_exit(callout, arg, frame) if (p->p_flag & P_KTHREAD) { printf("Kernel thread \"%s\" (pid %d) exited prematurely.\n", td->td_name, p->p_pid); - kproc_exit(0); + kthread_exit(); } mtx_assert(&Giant, MA_NOTOWNED);