[Devel] Re: ckpt-v20-dev, ckpt-v21-rc1

[Nathan Lynch]

On Thu, 2010-04-01 at 14:10 -0500, Serge E. Hallyn wrote:
> Quoting Nathan Lynch (ntl at pobox.com):
> > On Thu, 2010-04-01 at 13:09 -0500, Nathan Lynch wrote:
> > > On Thu, 2010-04-01 at 09:17 -0500, Serge E. Hallyn wrote:
> > > > Alas after I sent this Nathan reported trouble on x86.  I haven't
> > > > gotten a x86-32 partition running yet so can't reproduce.  Does
> > > > anyone else have x86-32 with f12 they can test on?
> > > 
> > > More detail on this.  Seeing programs crash after restart on an i386 KVM
> > > guest with Fedora 12 userspace, e.g.
> > > 
> > > bash-simple.sh[3627] general protection ip:b76d8197 sp:bfe73904 error:0
> > > in libc-2.11.1.so[b760e000+16f000]
> > > 
> > > kernel: ckpt-v21-rc1 (v2.6.33-108-g9f4401c)
> > > 
> > > user-cr: ckpt-v20 ( 70a5c7630ce8dd933e60174aba6dc5cb08ea4b41) with
> > > CHECKPOINT_NONETNS flag added to checkpoint calls
> > 
> > Confirmed that behavior is the same with user-cr ckpt-v20-dev
> > (7bd883e17f25d36d66f9b550194c445df2f63e7e).
> > 
> > > 
> > > cr_tests: master (7bd883e17f25d36d66f9b550194c445df2f63e7e) with
> > > CHECKPOINT_NONETNS flag added to simple/ckpt.c.
> > > 
> > > The "simple" (self-checkpoint) testcase restarts successfully without
> > > crashing.  Everything else seems to get crashes as above.  As far as I
> > > can tell the memory map is restored correctly and from the kernel's POV
> > > the restart is successful.
> > > 
> > > FWIW, I don't see these crashes on another KVM guest where the only
> > > difference is that it is x86_64.
> > 
> 
> I just (finally) finished install and setup of f12 x86 kvm container,
> and it seems to be passing.  (well cloop_parallel seems to need more
> than the 10 second timeout to check all tasks are restarted, but they
> do restart - I do have kvm constrained with memory and cpu cgroups :).

On the problem guest I booted a 64-bit kernel configured similarly to
the i386 one, and the crashes do not occur.  That is, I'm running 32-bit
userspace on a 64-bit kernel.  So the issue is likely specific to the
i386 c/r implementation and my particular version of kvm or host kernel
(which is also Fedora 12).


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