Re: kern/52199 (vioscsi kernel panic on a KVM hypervisor)

[Jaromír Doleček <jaromir.dolecek%gmail.com@localhost>]

The following reply was made to PR kern/52199; it has been noted by GNATS.

From: =?UTF-8?B?SmFyb23DrXIgRG9sZcSNZWs=?= <jaromir.dolecek%gmail.com@localhost>
To: gnats-bugs%netbsd.org@localhost
Cc: code%boerschig.net@localhost
Subject: Re: kern/52199 (vioscsi kernel panic on a KVM hypervisor)
Date: Tue, 16 May 2017 00:02:15 +0200

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 Hello,
 
 committed another fix for the resource shortage, messages and related i/o
 delays should be gone for good. You can grab just the new kernel from
 NetBSD-daily once it gets built.
 
 Thanks for the reproduction instructions. I did see the resource shortages
 during sysinst extracting, but unfortunately I wasn't able to trigger the
 lockup using the dd's so far. I'm using QEMU 2.9, and I haven't try with
 KVM yet. I don't see anything related in release notes for 2.6-2.9, so
 maybe my non-kvm QEMU is too slow to trigger the problem.
 
 Can you let me know if the latest fix by chance helps with the lockup too?
 
 And can you please try without --enable-kvm too?
 
 Another thing to try would be to compile&run custom kernel with LOCKDEBUG
 and DEBUG options enabled. If the freeze is due to locking issue, those
 options help to find the problematic spot.
 
 Jaromir
 
 2017-05-14 21:25 GMT+02:00 MB <code%boerschig.net@localhost>:
 
 >  Thanks for your work.
 >  The installation works now, allthough the "resource shortage" messages
 > appear.
 >  The 'resource shortage' messages also seem to affect the write
 > performance.
 >  However, I see some strange behavior and I'm not sure if it is related to
 > the vioscsi driver:
 >
 >  After installation, I put some load on the virtual disk, and the whole
 > system seems to freeze.
 >  Once it continued after a couple of minutes, currently it is wedged for
 > 10min+..
 >  FWIW, I could produce this on a 10gb test image, default installation,
 > with the following, but only on 3 out of 8 attempts:
 >
 >  dd if=/dev/urandom of=/home/test1.bin bs=1m count=128
 >  ls -lahR /
 >  for i in $(seq 0 8);do dd if=/home/test1.bin of=/home/foo$i ;done
 >  #when the system freezes, here are no "adapter resource shortage"
 > messages, they only appear when the system works without freeze
 >  ls -lahR /
 >  for i in $(seq 0 8);do dd if=/home/test1.bin of=/home/foo$i ;done
 >  #this freezes, no keyboard input, not even '(qemu) sendkey ctrl-alt-f2'
 >
 >
 
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 <div dir=3D"ltr">Hello,<div><br></div><div>committed another fix for the re=
 source shortage, messages and related i/o delays should be gone for good. Y=
 ou can grab just the new kernel from NetBSD-daily once it gets built.</div>=
 <div><br></div><div>Thanks for the reproduction instructions. I did see the=
  resource shortages during sysinst extracting, but unfortunately I wasn&#39=
 ;t able to trigger the lockup using the dd&#39;s so far. I&#39;m using QEMU=
  2.9, and I haven&#39;t try with KVM yet. I don&#39;t see anything related =
 in release notes for 2.6-2.9, so maybe my non-kvm QEMU is too slow to trigg=
 er the problem.</div><div><br></div><div>Can you let me know if the latest =
 fix by chance helps with the lockup too?</div><div><br></div><div>And can y=
 ou please try without --enable-kvm too?</div><div><br></div><div>Another th=
 ing to try would be to compile&amp;run custom kernel with LOCKDEBUG and DEB=
 UG options enabled. If the freeze is due to locking issue, those options he=
 lp to find the problematic spot.</div><div><br></div><div>Jaromir</div><div=
 ><br></div><div><div class=3D"gmail_extra"><div class=3D"gmail_quote">2017-=
 05-14 21:25 GMT+02:00 MB <span dir=3D"ltr">&lt;<a href=3D"mailto:code@boers=
 chig.net" target=3D"_blank">code%boerschig.net@localhost</a>&gt;</span>:<br><blockquo=
 te class=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;border-left:1px #ccc so=
 lid;padding-left:1ex">=C2=A0Thanks for your work.<br>
 =C2=A0The installation works now, allthough the &quot;resource shortage&quo=
 t; messages appear.<br>
 =C2=A0The &#39;resource shortage&#39; messages also seem to affect the writ=
 e performance.<br>
 =C2=A0However, I see some strange behavior and I&#39;m not sure if it is re=
 lated to the vioscsi driver:<br>
 <br>
 =C2=A0After installation, I put some load on the virtual disk, and the whol=
 e system seems to freeze.<br>
 =C2=A0Once it continued after a couple of minutes, currently it is wedged f=
 or 10min+..<br>
 =C2=A0FWIW, I could produce this on a 10gb test image, default installation=
 , with the following, but only on 3 out of 8 attempts:<br>
 <br>
 =C2=A0dd if=3D/dev/urandom of=3D/home/test1.bin bs=3D1m count=3D128<br>
 =C2=A0ls -lahR /<br>
 =C2=A0for i in $(seq 0 8);do dd if=3D/home/test1.bin of=3D/home/foo$i ;done=
 <br>
 =C2=A0#when the system freezes, here are no &quot;adapter resource shortage=
 &quot; messages, they only appear when the system works without freeze<br>
 =C2=A0ls -lahR /<br>
 =C2=A0for i in $(seq 0 8);do dd if=3D/home/test1.bin of=3D/home/foo$i ;done=
 <br>
 =C2=A0#this freezes, no keyboard input, not even &#39;(qemu) sendkey ctrl-a=
 lt-f2&#39;<br>
 <br>
 </blockquote></div><br></div></div></div>
 
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