From owner-freebsd-current@freebsd.org Sat Apr 7 19:56:12 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 2D273FA2F45 for ; Sat, 7 Apr 2018 19:56:12 +0000 (UTC) (envelope-from truckman@FreeBSD.org) Received: from mx2.catspoiler.org (mx2.catspoiler.org [IPv6:2607:f740:16::d18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client CN "amnesiac", Issuer "amnesiac" (not verified)) by mx1.freebsd.org (Postfix) with ESMTPS id 679816F279; Sat, 7 Apr 2018 19:56:11 +0000 (UTC) (envelope-from truckman@FreeBSD.org) Received: from gw.catspoiler.org ([76.212.85.177]) by mx2.catspoiler.org (8.15.2/8.15.2) with ESMTPS id w37JvJ4N084009 (version=TLSv1.2 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=FAIL); Sat, 7 Apr 2018 19:57:21 GMT (envelope-from truckman@FreeBSD.org) Received: from mousie.catspoiler.org (mousie.catspoiler.org [192.168.101.2]) by gw.catspoiler.org (8.15.2/8.15.2) with ESMTPS id w37Ju1uE032427 (version=TLSv1 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Sat, 7 Apr 2018 12:56:02 -0700 (PDT) (envelope-from truckman@FreeBSD.org) Date: Sat, 7 Apr 2018 12:55:56 -0700 (PDT) From: Don Lewis Subject: Re: Strange ARC/Swap/CPU on yesterday's -CURRENT To: Justin Hibbits cc: Mark Johnston , Jeff Roberson , FreeBSD current In-Reply-To: Message-ID: References: <20180320070745.GA12880@server.rulingia.com> <2b3db2af-03c7-65ff-25e7-425cfd8815b6@FreeBSD.org> <1fd2b47b-b559-69f8-7e39-665f0f599c8f@FreeBSD.org> <20180404174949.GA12271@raichu> <20180406150814.GB10017@raichu> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; CHARSET=us-ascii Content-Disposition: INLINE 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: Sat, 07 Apr 2018 19:56:12 -0000 On 7 Apr, Justin Hibbits wrote: > On Fri, Apr 6, 2018 at 10:25 AM, Justin Hibbits wrote: >> On Fri, Apr 6, 2018 at 10:08 AM, Mark Johnston wrote: >>> On Fri, Apr 06, 2018 at 12:47:14AM +0000, Justin Hibbits wrote: >>>> My powerpc64 embedded machine is virtually unusable since these vm changes. >>>> I tried setting vfs.zfs.arc_free_target as suggested, and that didn't help >>>> at all. Eventually the machine hangs and just gets stuck in vmdaemon, with >>>> many processes in wait channel btalloc. >>> >>> You don't really have the same symptoms that Don is reporting. >> >> Okay. I latched onto the thread because it seemed similar. >> >>> Threads being stuck in btalloc implies a KVA shortage. So: >>> - What do you mean by "stuck in vmdaemon"? >> >> The machine hangs, and my ssh sessions get killed. I can't do >> anything at the console except break into kdb. When I do, the running >> thread is always vmdaemon. >> >>> - Which commits specifically cause problems? Does reverting r329882 fix the >>> hang? >> >> I'll try reverting it and report back. Thankfully I can buildkernel >> successfully on the machine before it hangs. Can't do more than that, >> though. > > I reverted back to r329881, and successfully built world. Updated to > r329882 and it got stuck with processes in btalloc. > > I've seen other reports of r329882 causing problems on powerpc64 as > well, with other bizarre behaviors. I initially missed that this was on powerpc. I believe that arch is a bit odd with characters unsigned by default and arithmentic shifts always being unsigned. Things like that could mess up the algorithm, but I didn't see anything suspicious in the r329882 diff.