Date: Thu, 24 Sep 1998 13:05:49 +0300 (EEST) From: Alexander Litvin <archer@lucky.net> To: Luoqi Chen <luoqi@watermarkgroup.com> Cc: current@FreeBSD.ORG Subject: Re: deadlock in vm_fault() Message-ID: <199809241005.NAA14277@grape.carrier.kiev.ua> In-Reply-To: <199809232224.SAA17260@lor.watermarkgroup.com>
next in thread | previous in thread | raw e-mail | index | archive | help
In article <199809232224.SAA17260@lor.watermarkgroup.com> you wrote: LC> I ran into a deadlock in vm_fault code today while making -j12 world. LC> It's caused by a reversed lock acquisition order. The normal order of LC> acquisition is vm map lock first and vnode lock next (if the fault is in LC> a vnode backed object). During the course of the fault handling, lock on LC> the vm map is released prior to paging io and has to be reacquired if it's LC> modified by another process during the io. Before reacquiring the lock of LC> vm map, we have to release the vnode lock we still hold, otherwise another LC> page fault in the same map/vnode would send us into a deadlock. LC> Attached is a fix for this problem. Would any of the vm/lock experts out LC> there review this? Thanks. I've seen something strange during the same -j12 buildworld. In fact, it was just that ld hang, apparently not doing anything. The rest of the system seemed to be alive. Though in some 3 or 4 hours machine rebooted (it had kernel with broken crash dump generation, so I do not know what actually happened). May it be related? LC> -lq --- Reality is an obstacle to hallucination. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?199809241005.NAA14277>