Re: [Bug #14388] keyboard under X with 2.6.31

Linus Torvalds
2009-10-13T15:05:07Z

On Tue, 13 Oct 2009, Boyan wrote:
>
> I've just tested it on top of 2.6.31.3 and it doesn't work. As I've
> mentioned in previous email - I usually trigger the problem easily
> watching pictures with gthumb - this is combination of cpu intensive
> operations and keyboard usage and if it doesn't work it takes me no more
> than a minute to trigger the problem.

The whole "CPU intensive" thing makes me wonder..

Do you have 'CONFIG_PREEMPT' enabled? Normally, "CPU intensive" does not
at all increase the likelihood of any kernel races, but with kernel
preemption we may well hit some preemption point and switch away, and make
some race window much bigger.

So if you do have CONFIG_PREEMPT on, try to turn it off and see if it
makes the problem go away. Also, are people seeing this always running SMP
kernels, or are there UP kernels out there too (on UP _without_ preemption
it is almost impossible to hit 99% of all race conditions, so if anybody
is running an UP kernel with no preemption, then I'd be very surprised if
it is a kernel issue).

But I also still wonder if it might be user-space races, and just the
timing differences in the kernel. I don't know the input layer in X well
enough, I'm wondering if things like composition engine/window manager
could screw up here. Is there some pattern to the X versions (and/or
window managers and composition engines)?

Linus