Re: + proc-dont-lock-task_structs-indefinitely-cpuset-fix-2.patch added to -mm tree

Eric W. Biederman
2006-03-01T04:38:09Z

Paul Jackson <pj@sgi.com> writes:

>> -rc5-mm1 appears to be a trainwreck. It's a bit of a mystery - I've tried
>> several further configs and it all works swimmingly.
>
> Getting closer.
>
> Without the patches:
>
> proc-dont-lock-task_structs-indefinitely.patch
> proc-dont-lock-task_structs-indefinitely-git-nfs-fix.patch
> proc-dont-lock-task_structs-indefinitely-cpuset-fix.patch

That definitely makes sense if there is a reference counting bug
somewhere.

What is also possible but scary is that I don't have a reference
counting bug and something else is wrong with process management,
and by holding a much lighter grasp on the tasks in /proc
I have managed to make the bug much easier to trigger.

Hmm. I think I can see at least one reference counting bug..
Unfortunately it is in the wrong direction.

> With these patches, it still boots, and looks fine ... until
> I fire up my SGI specific application, and then it dies.
> Once it died with some complaint (lost now) from a swap
> daemon. This latest time, it died with just:
>
> Kernel panic - not syncing: Attempted to kill init!

Ouch.

> So I think the above 3 patches make it easy for user space
> to kill the kernel.

The intent was the opposite... But until the bugs get out...

Eric