From owner-freebsd-current@freebsd.org Sun Apr 22 13:29:07 2018 Return-Path: Delivered-To: freebsd-current@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 65E9DF928F1 for ; Sun, 22 Apr 2018 13:29:07 +0000 (UTC) (envelope-from kostikbel@gmail.com) Received: from kib.kiev.ua (kib.kiev.ua [IPv6:2001:470:d5e7:1::1]) (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 E1C8B71F84; Sun, 22 Apr 2018 13:29:06 +0000 (UTC) (envelope-from kostikbel@gmail.com) Received: from tom.home (kib@localhost [127.0.0.1]) by kib.kiev.ua (8.15.2/8.15.2) with ESMTPS id w3MDStiC099568 (version=TLSv1.2 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=NO); Sun, 22 Apr 2018 16:28:59 +0300 (EEST) (envelope-from kostikbel@gmail.com) DKIM-Filter: OpenDKIM Filter v2.10.3 kib.kiev.ua w3MDStiC099568 Received: (from kostik@localhost) by tom.home (8.15.2/8.15.2/Submit) id w3MDSttO099567; Sun, 22 Apr 2018 16:28:55 +0300 (EEST) (envelope-from kostikbel@gmail.com) X-Authentication-Warning: tom.home: kostik set sender to kostikbel@gmail.com using -f Date: Sun, 22 Apr 2018 16:28:55 +0300 From: Konstantin Belousov To: Tijl Coosemans Cc: jeff@FreeBSD.org, "freebsd-current@freebsd.org" Subject: Re: i386 hangs during halt "vnodes remaining... 0 time out" Message-ID: <20180422132855.GU6887@kib.kiev.ua> References: <20180421234934.10d7dfab@kalimero.tijl.coosemans.org> <20180422120521.GS6887@kib.kiev.ua> <20180422151500.1608af96@kalimero.tijl.coosemans.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180422151500.1608af96@kalimero.tijl.coosemans.org> User-Agent: Mutt/1.9.5 (2018-04-13) X-Spam-Status: No, score=-2.0 required=5.0 tests=ALL_TRUSTED,BAYES_00, DKIM_ADSP_CUSTOM_MED,FREEMAIL_FROM,NML_ADSP_CUSTOM_MED autolearn=no autolearn_force=no version=3.4.1 X-Spam-Checker-Version: SpamAssassin 3.4.1 (2015-04-28) on tom.home X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.25 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 22 Apr 2018 13:29:07 -0000 On Sun, Apr 22, 2018 at 03:15:00PM +0200, Tijl Coosemans wrote: > On Sun, 22 Apr 2018 15:05:21 +0300 Konstantin Belousov wrote: > > On Sat, Apr 21, 2018 at 11:49:34PM +0200, Tijl Coosemans wrote: > >> On Sat, 21 Apr 2018 21:09:09 +0000 Rick Macklem wrote: > >>> With a recent head/current kernel (doesn't happen when running a Dec. > >>> 2017 one), when I do a halt, it gets as far as: > >>> > >>> vnodes remaining... 0 time out > >>> > >>> and that's it (the time out appears several seconds after the first "0"). > >>> With a Dec. 2017 kernel there would be several "0"s printed. > >>> It appears that it is stuck in the first iteration of the sched_sync() > >>> loop after it is no longer in SYNCER_RUNNING state. > >>> > >>> Any ideas? rick > >> > >> See https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=227404 > >> I have a patch (attached) but haven't been able to test it yet. > >> > >> Index: sys/kern/vfs_bio.c > >> =================================================================== > >> --- sys/kern/vfs_bio.c (revision 332165) > >> +++ sys/kern/vfs_bio.c (working copy) > >> @@ -791,9 +791,12 @@ bufspace_daemon(void *arg) > >> { > >> struct bufdomain *bd; > >> > >> + EVENTHANDLER_REGISTER(shutdown_pre_sync, kthread_shutdown, curthread, > >> + SHUTDOWN_PRI_LAST); > >> + > >> bd = arg; > >> for (;;) { > >> - kproc_suspend_check(curproc); > >> + kthread_suspend_check(); > >> > >> /* > >> * Free buffers from the clean queue until we meet our > >> @@ -3357,7 +3360,7 @@ buf_daemon() > >> /* > >> * This process needs to be suspended prior to shutdown sync. > >> */ > >> - EVENTHANDLER_REGISTER(shutdown_pre_sync, kproc_shutdown, bufdaemonproc, > >> + EVENTHANDLER_REGISTER(shutdown_pre_sync, kthread_shutdown, curthread, > >> SHUTDOWN_PRI_LAST); > >> > >> /* > >> @@ -3381,7 +3384,7 @@ buf_daemon() > >> bd_request = 0; > >> mtx_unlock(&bdlock); > >> > >> - kproc_suspend_check(bufdaemonproc); > >> + kthread_suspend_check(); > >> > >> /* > >> * Save speedupreq for this pass and reset to capture new > > This looks fine. > > Thanks for the review. There's just one concern I have. With this patch > the bufspace_daemon threads appear to shutdown after the buf_daemon and > after the syncer because the event handlers are registered later. Are > there any dependencies between these processes that require the bufspace > threads to be stopped earlier? I think for correctness bufdaemon must stop after the syncer, since syncer operation can cause a situation where bufdaemon help is needed to proceed. Other than this, the stop order is irrelevant, because after syncer finished, there should be no any further filesystem activity.