[Devel] Re: 2.6.33-rc4 i686 clone function looping (seems real!)

[Serge E. Hallyn]

Quoting Jean-Marc Pigeon (jmp at safe.ca):
> Hello Serge,
> 
> 	Thanks for the small test, I do confirm
> 	there is the same problem here with it, 
> 	as soon started the program use ALL available 
> 	CPU cycle (minus some few %) and NEVER
> 	EVER come back from "clone" function.
> 	The ONLY way I found to recover the
> 	system is to power it down (sic!).
> 
> 	See attachment, your program, the 
> 	.config file, and cpu information
> 	(I put back your test too, (done 
> 	 cosmetic changes only)).
> 
> 	Once again, clone call on 2.6.32.3
> 	is working fine.
> 
> 	Sorry to bother the list, I was "expecting"
> 	a Stack size problem, but I increase
> 	your value from 4 to 10, with the same result.
> 	Hopefully it could be something I overlooked
> 	with my Kernel config file, if someone
> 	want to have a look I attached it.
> 
> 	My guess for now it is something within
> 	the clone code specific to i386.
> 	
> 	I 'll try to pin point within the 
> 	clone code.
> 
> 	(could someone check tstclone.c under 
> 	 i386 arch and confirm trouble?)

I just tried it on a x86-32 kvm image with no hang (cut-n-paste
from your copy of testclone.c).

Could you:

	1. use cpusets and memory limiter to limit the
	   shell fromwhich you run testclone to 1 cpu and
	   1/3 of your ram,
	2. fire up testclone
	3. gdb -se testclone -p `pidof testclone` in another
	   shell and see whether anything is hung in userspace?

If you need more specific hints pls let me know.

Also, you might try with selinux disabled ('setenforce 0'), though
I don't see how it can be responsible.

-serge
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