From owner-freebsd-fs@freebsd.org Wed Mar 2 11:02:05 2016 Return-Path: Delivered-To: freebsd-fs@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 5D057AC1BBD for ; Wed, 2 Mar 2016 11:02:05 +0000 (UTC) (envelope-from sobomax@sippysoft.com) Received: from mail-wm0-x231.google.com (mail-wm0-x231.google.com [IPv6:2a00:1450:400c:c09::231]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority G2" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id B11871BFB for ; Wed, 2 Mar 2016 11:02:04 +0000 (UTC) (envelope-from sobomax@sippysoft.com) Received: by mail-wm0-x231.google.com with SMTP id p65so72347789wmp.0 for ; Wed, 02 Mar 2016 03:02:04 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=sippysoft-com.20150623.gappssmtp.com; s=20150623; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc; bh=LZpjuCunY1PrcBphr3AjEXT/J/+yM52qJrdKzKAm+c0=; b=y22X0KdTWetTnwVajf7TM5HAXoldy4j0D7PTid2WCZbPxPDNlrvtLwJb1oiEnX8xb2 KbddKvj68XXsaY4TKwfKloQAaMKl7muVn7pmgYsX8m4fTsK890cH7RugEWvPHx5u14e6 7s4F3h6oejYO3cb+CRwnRnItwxaE071s/B+dgp/lMIx8Xl9LUAQqx/4Dw32N+ZJZGR5R jL1HY3GvekKg0duxBhTApUqpnNrY/LRwbIb6vH3/6iv1RZfYVcC50/3Vz2XWeMR2JMwD XJ90dl1C6zNlyxLk9nnn1I0moLc4pDaSJA3jTwz1NI20CXkV+A0rP90M3b0z2uslqclH N5Sw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:mime-version:in-reply-to:references:date :message-id:subject:from:to:cc; bh=LZpjuCunY1PrcBphr3AjEXT/J/+yM52qJrdKzKAm+c0=; b=emNnG+bhW5siQaMyg5BWrpIUkbdNJ5dEP0AUF349p0DFGN8Yj2/mw21bRlKAsqctTA ZnIOyTkmdc3cWDZP5GGKE9z070UWbqekSRbqN88iqLzkY25G3dX5LvrFnMDPBZ8Sw5sj c8F+51IrEY0aFA76GjN0bSGCl2C33fLmLVxkIkhwagAMTbb0tIU4+DhCr9KesNpoXisZ UnT3B6IHJ6yhHHjm0jAI/Q7uJblF+ZfCuxuMJfmGk0w895T5fDbtj/noIcaX+kU2P57C 12FGE3XyMsIse+rNeNe1lrT8RnUe1Qb1YNiHB/MQLOGVzFSDzBhom/HRF7mE/TA0aD35 kjeg== X-Gm-Message-State: AD7BkJKrtLcUXe2NdggC1VQY7Gv/ga9YcL63fXjtT55fAmEJd0FyXHgNv5nfVfHceYRoAZ2qrmH1f5CyimXrUg4c MIME-Version: 1.0 X-Received: by 10.28.228.214 with SMTP id b205mr4281196wmh.94.1456916522736; Wed, 02 Mar 2016 03:02:02 -0800 (PST) Received: by 10.27.218.12 with HTTP; Wed, 2 Mar 2016 03:02:02 -0800 (PST) In-Reply-To: <20160302095339.GB67250@kib.kiev.ua> References: <20160302095339.GB67250@kib.kiev.ua> Date: Wed, 2 Mar 2016 03:02:02 -0800 Message-ID: Subject: Re: Process stuck in "vnread" From: Maxim Sobolev To: Konstantin Belousov Cc: stable@freebsd.org, freebsd-fs@freebsd.org, Kirk McKusick Content-Type: text/plain; charset=UTF-8 X-Content-Filtered-By: Mailman/MimeDel 2.1.20 X-BeenThere: freebsd-fs@freebsd.org X-Mailman-Version: 2.1.20 Precedence: list List-Id: Filesystems List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 02 Mar 2016 11:02:05 -0000 Thanks, Konstantin. Re: md(4) state: 0 88688 0 0 -8 0 0 16 tx->tx_s DL - 0:45.43 [md0] Its backtrace: About the backtrace, indeed, looks like you are right and some portion of it is not decoded properly, as it's loaded as a kernel module. The setup is somewhat even more complicated, the /usr/ports is mounted via NULLFS, so in this command: cp /usr/local/share/automake-1.15/compile ./compile The target (i.e. ./compile) here is a path on ZFS that is exported via NULLFS, while the source is a file on UFS2->md->ZFS. This is probably the reason stack trace is incomplete, both zfs.ko and nullfs.ko are loaded as modules and the next few frames point towards those. Unfortunately I cannot beat kgdb to read symbols from those .ko's and decode them. #13 0xffffffff80cb36f1 in copyin () #14 0xffffffff80977ddf in uiomove_faultflag () #15 0xffffffff819f699c in ?? () #16 0xfffffe0468a861a0 in ?? () #17 0xfffff80000000000 in ?? () #18 0xfffffe0468a861a0 in ?? () #19 0xfffff80176b39420 in ?? () #20 0x0000000000000001 in ?? () $ kldstat | grep 0xffffffff819 2 1 0xffffffff819bd000 aef8 nullfs.ko 3 1 0xffffffff819c8000 2fd2f0 zfs.ko On Wed, Mar 2, 2016 at 1:53 AM, Konstantin Belousov wrote: > On Wed, Mar 02, 2016 at 01:12:31AM -0800, Maxim Sobolev wrote: > > Hi, I've encountered cp(1) process stuck in the vnread state on one of my > > build machines that got recently upgraded to 10.3. > > > > 0 79596 1 0 20 0 17092 1396 wait I 1 > 0:00.00 > > /bin/sh /usr/local/bin/autoreconf -f -i > > 0 79602 79596 0 52 0 41488 9036 wait I 1 > 0:00.07 > > /usr/local/bin/perl -w /usr/local/bin/autoreconf-2.69 -f -i > > 0 79639 79602 0 72 0 0 0 - Z 1 > 0:00.27 > > > > 0 79762 79602 0 20 0 17092 1396 wait I 1 > 0:00.00 > > /bin/sh /usr/local/bin/automake --add-missing --copy --force-missing > > 0 79768 79762 0 52 0 49736 13936 wait I 1 > 0:00.11 > > /usr/local/bin/perl -w /usr/local/bin/automake-1.15 --add-missing --copy > > --force-missing > > 0 79962 79768 0 20 0 12368 1024 vnread DL 1 > 0:00.00 > > cp /usr/local/share/automake-1.15/compile ./compile > > > > I am not sure if it's related to that OS version upgrade, but I have not > > seen any such issues on the same machine in 2-3 years running essentially > > the same build process with version 9.x, 10.0, 10.1 and 10.2. > > > > $ uname -a > > FreeBSD van01.sippysoft.com 10.3-PRERELEASE FreeBSD 10.3-PRERELEASE #1 > > 80de3e2(master)-dirty: Tue Feb 2 12:19:57 PST 2016 > > sobomax@abc.sippysoft.com: > /usr/obj/usr/home/sobomax/projects/freebsd103/sys/ABC > > amd64 > > > > The kernel stack trace is: > > > > (kgdb) thread 360 > > [Switching to thread 360 (Thread 100515)]#0 0xffffffff8095244e in > > sched_switch () > > (kgdb) bt > > #0 0xffffffff8095244e in sched_switch () > > #1 0xffffffff809313b1 in mi_switch () > > #2 0xffffffff8097089a in sleepq_wait () > > #3 0xffffffff80930dd7 in _sleep () > > #4 0xffffffff809b230e in bwait () > > #5 0xffffffff80b511f3 in vnode_pager_generic_getpages () > > #6 0xffffffff80dd1607 in VOP_GETPAGES_APV () > > #7 0xffffffff80b4f59a in vnode_pager_getpages () > > #8 0xffffffff80b30031 in vm_fault_hold () > > #9 0xffffffff80b2f797 in vm_fault () > > #10 0xffffffff80cb5a75 in trap_pfault () > > #11 0xffffffff80cb51dd in trap () > > #12 0xffffffff80c9b122 in calltrap () > > #13 0xffffffff80cb36f1 in copyin () > > #14 0xffffffff80977ddf in uiomove_faultflag () > The backtrace indicates, with 99% certainity that the issue is in the > requested read never finishing. But the backtrace is obviously not > complete, and there might be something more happening. At least, > we do not handle page-ins during uiomove() on user io for quite > some time. > > If the vnode which io hung is UFS over md, you should look at the md > worker thread state. > > > > > The FS stack configuration is somewhat unique, so I am not sure if I am > > hitting some rare race condition or lock ordering issues specific to > that. > > It's basically ZFS (ZRAID) on top of pair or SATA SSDs with big file on > > that FS attached via md(4) and UFS2 on that md(4). The build itself runs > in > > chroot with that UFS2 fs as its primary root. > > > > Just maybe additional bit of info, attempting to list the directory with > > that UFS image also got my bash process stuck in "zfs" state, backtrace > > from that is: > A deadlock in the underlying io layer is consistent with this (secondary) > observation. > > > > > (kgdb) thread 353 > > [Switching to thread 353 (Thread 100508)]#0 0xffffffff8095244e in > > sched_switch () > > (kgdb) bt > > #0 0xffffffff8095244e in sched_switch () > > #1 0xffffffff809313b1 in mi_switch () > > #2 0xffffffff8097089a in sleepq_wait () > > #3 0xffffffff809069ad in sleeplk () > > #4 0xffffffff809060e0 in __lockmgr_args () > > #5 0xffffffff809b8b7c in vop_stdlock () > > #6 0xffffffff80dd0a3b in VOP_LOCK1_APV () > > #7 0xffffffff809d6d23 in _vn_lock () > > #8 0xffffffff81a8c9cd in ?? () > > #9 0x0000000000000000 in ?? () > > -- Maksym Sobolyev Sippy Software, Inc. 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