Date: Tue, 31 May 2005 16:47:19 -0700 From: steve@Watt.COM (Steve Watt) To: efinleywork@efinley.com Cc: stable@freebsd.org Subject: Re: 5.4-RC2 freezing - ATA related? Message-ID: <200505312347.j4VNlKgF064965@wattres.watt.com> In-Reply-To: <08dc01c55d47$d7697100$37cba1cd@emerytelcom.com> References: <001801c55a14$609720d0$37cba1cd@emerytelcom.com> <20050516195859.GA59189@server.vk2pj.dyndns.org> <042501c55ba7$360fac30$37cba1cd@emerytelcom.com> <20050518194356.GA2129@cirb503493.alcatel.com.au>
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In <08dc01c55d47$d7697100$37cba1cd@emerytelcom.com>, efinleywork@efinley.com writes: >From: "Peter Jeremy" <PeterJeremy@optushome.com.au> >> On Wed, 2005-May-18 06:43:37 -0600, Elliot Finley wrote: >> >Had the system lock up again. This is with the new ATA mkIII patches on >> >http://people.freebsd.org/~sos/ATA. >> > >> >I didn't get the crashdump (forgot to set dumpdev), but I did get 'ps' >and >> >'show lockedvnods' output from DDB. The output is in the form of >> >screenshots combined into a single .pdf which can be accessed here >> >http://www.efinley.com/Binder1.pdf >> >> That shows a deadlock-to-root in your /dev/ar0s1a (presumably root) >> filesystem. The perl process (pid 487) has an exclusive lock on >> the FS mountpoint - this is blocking 130 other processes. Pid 487 >> is itself waiting on another filesystem lock (you can't determine >> the actual lock tree without more poking around kernel memory). >> >> The vnode locks are held by processes: >> PID name waiting on >> 487 perl [ufs c3c1c1b4] >> 57 syncer [snaplk c535f500] (holds 2 locks) >> 476 perl [ufs c87e4f1c] >> 489 perl [snaplk c535f500] (holds 2 locks) >> 3337 mksnap_ffs [getblk d77656f4] >> >> Looking through the process list, cron has started a "dump -L" which >> is trying to create a filesystem snapshot. That has wedged on >> "getblk" (trying to perform physical disk I/O) and is probably the >> root of your problem. Nothing else is waiting on physical I/O. >> >> I'd say that your first guess was right: This is a bug in the ATA >> code and is probably a job for sos. > >I took the -L option off of my dump command in my daily dump script. I've >gone two days without locking up which is unusual. I think that may be what >was tickling the bug that was locking me up. This is a filesystem lock problem, not an ATA driver problem. I analyzed it, and posted the results to -hackers last week, with the subject "snapshots and innds". The problem is that there is an invariant being broken in msync() -- Kirk describes it fully in his reply to my message. -- Steve Watt KD6GGD PP-ASEL-IA ICBM: 121W 56' 57.8" / 37N 20' 14.9" Internet: steve @ Watt.COM Whois: SW32 Free time? There's no such thing. It just comes in varying prices...
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