Date: Sat, 30 Nov 2002 19:01:48 +0100 (CET) From: Michal Mertl <mime@traveller.cz> To: current@freebsd.org Cc: rwatson@freebsd.org Subject: Re: system locks with vnode backed md(4) Message-ID: <Pine.BSF.4.41.0211301833040.82532-100000@prg.traveller.cz> In-Reply-To: <Pine.BSF.4.41.0211301330040.60923-100000@prg.traveller.cz>
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On Sat, 30 Nov 2002, Michal Mertl wrote: Including rwatson because of the thread on hackers@. Sorry for follow-up to myself. > Recently there was a discussion about jails on some freebsd list. Someone > recommended vnconfig(8)ed file-backed disk for jail file systems. Terry > wrote there are problems with it. I liked the idea and played with > mdconfig(8)ed devices on current. Terry was right - I can easily make the > system deadlock. I really like the idea of jails in vnode-backed I'm now unable to make it dead-lock again. Yet it happened quite easily. I had more md backing files in the same directory at the beginning (to test Terry's suspicion mentioned in thread 'jail' on hackers@). After the first lock-up I tried 'while(1);tar xzf ports.tgz; rm -rf ports;end' on normal filesystem, let it run for long time (> 1h) and then I found the system almost dead-locked too (the system worked, but anything accessing disk was painfully slow - it might be the same problem or it might be different. It never ended (at least for > ~30 mins when I didn't (weren't able) anything on it). syncer and bufdaemon and others were in wdrain. Disk as seen in systat -v showed maximal usage yet no inodes were resolved. Sometimes during that test I had lock order reversal: ../../../kern/kern_synch.c:152: sleeping with "mntvnode" locked from ../../../kern/vfs_subr.c:3016 lock order reversal 1st 0xc03a0aa0 mntvnode (mntvnode) @ ../../../kern/vfs_subr.c:3016 The 2nd isn't unfortunately saved in logs but it was Giant. I'll try to get more problems and get more info (show lockedvnods, show locks). show locks with first dead-lock showed only Giant AFAIR. -- Michal Mertl mime@traveller.cz To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message
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