Date: Sat, 8 Jan 2011 22:29:09 +0300 From: Lev Serebryakov <lev@freebsd.org> To: Kostik Belousov <kostikbel@gmail.com> Cc: freebsd-stable@freebsd.org Subject: Re: 8.2-PRERELEASE: live deadlock, almost all processes in "pfault" state Message-ID: <1792026896.20110108222909@serebryakov.spb.ru> In-Reply-To: <20110108190232.GU12599@deviant.kiev.zoral.com.ua> References: <204344488.20110108214457@serebryakov.spb.ru> <20110108190232.GU12599@deviant.kiev.zoral.com.ua>
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Hello, Kostik. You wrote 8 =FF=ED=E2=E0=F0=FF 2011 =E3., 22:02:32: > There is some weird backtrace at the pid 20, what is g_raid5 ? It is geom_raid5, with two threads -- working one and one for processing finished bios. > If I am guessing right, this creature has a classic deadlock when=20 > bio processing requires memory allocation. It seems that tid 100079 tid 100079 sleep in waiting for some data in queue. > is sleeping not even due to the free page shortage, but due to address > space exhaustion. As result, read/write requests are stalled. tid 100078 sleep in malloc(). But geom_raid5 never ever allocate more than 128MiB of memory and it is 64bit system with huge amount of kmem_size/kmem_size_max... How could I explore allocation (like vmstat -m) from kdb to be sure, it doesn't allocated more? And, if it is "classic deadlock" is here any "classical" solution to it? Really, I'm maintainer of geom_raid5 now, so I need fix this deadlock, but I don't really understand, why does it occur? I've hit panic with "kernel memory exhausted" symptoms when module allocate too much, but not deadlock :( > Then, syncer is blocked waiting for some physical buffer (look at tid > 100075), owning the vnode lock. Other processes also wait for the > locked buffers, etc. > So my belief is that this is plain driver (g_raid5, whatever is it) > i/o loss. Try the same load without it. I can not, because all data is on this GEOM :) --=20 // Black Lion AKA Lev Serebryakov <lev@serebryakov.spb.ru>
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