Re: virtio balloon: do not call blocking ops when !TASK_RUNNING

On Thu, Feb 26, 2015 at 11:50:42AM +1030, Rusty Russell wrote:

Thomas Huth [off-list ref] writes:

quoted

 Hi all,

with the recent kernel 3.19, I get a kernel warning when I start my
KVM guest on s390 with virtio balloon enabled:

The deeper problem is that virtio_ccw_get_config just silently fails on
OOM.

Neither get_config nor set_config are expected to fail.

Cornelia, I think ccw and config_area should be allocated inside vcdev.
You could either use pointers, or simply allocate vcdev with GDP_DMA.

This would avoid the kmalloc inside these calls.

Thanks,
Rusty.

But it won't solve the problem of nested sleepers
with ccw: ATM is invokes ccw_io_helper to execute
commands, and that one calls wait_event
to wait for an interrupt.

Might be fixable but I think my patch looks like a safer
solution for 4.0/3.19, no?

-- 
MST