Re: [Bug 12134] New: can't shmat() 1GB hugepage segment from second process more than one time

[starlight@binnacle.cx]

At 12:57 12/5/2008 -0600, Adam Litke wrote:
>Great.  I was going to ask you to disable mlock() as well.  Is this the
>same machine that was running your workload on RHEL4 successfully?

No, that was a an old Athlon 4800+ dev box.

>One theory I've been contemplating is that, with all of the mlocking and
>threads, you might be running out of memory for page tables and that
>perhaps the hugetlb code is not handling that case correctly.

Seems unlikely.  Have 13GB of free RAM.

>When do
>the bad pmd messages appear?  When the daemon starts?  When the first
>separate process attaches?  When the second one does?  or later?

Only after a starting, stopping and attempting to restart the
server daemon.  The 'dmesg' errors don't appear synchronously
with the initial failure.

>
>> >If so, I could quickly bisect the kernel and identify the guilty 
>> >patch.  Without the program, I am left stabbing in the dark. 
>> >Could you try on a 2.6.18 kernel to see if it works or not?  
>> >Thanks.
>> 
>> Any particular version of 2.6.18?
>
>Nothing specific.  You could try 2.6.18.8 (latest -stable).  We could
>probably bisect this with approximately 8 kernel build-boot-test cycles
>if you are willing to engage on that.  I am looking forward to your
>disabled-mlock() results.

Ok, but this could take awhile.  Can only spare a few hours
a week on it.  Hopefully my suspicion of the fork() call is
on target.  Forking a 3GB process seems like an extreme
operation to me.

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