On Wed, Apr 19, 2017 at 01:03:59PM -0400, Keith Busch wrote:
> On Wed, Apr 19, 2017 at 09:20:27AM -0700, Andrei Vagin wrote:
> > Hi,
> >
> > Something is wrong with this patch. We run CRIU tests for upstream kernels.
> > And we found that a kernel with this patch can't be booted.
> >
> > https://travis-ci.org/avagin/linux/builds/223557750
> >
> > We don't have access to console logs and I can't reproduce this issue on
> > my nodes. I tired to revert this patch and everything works as expected.
> >
> > https://travis-ci.org/avagin/linux/builds/223594172
> >
> > Here is another report about this patch
> > https://lkml.org/lkml/2017/4/16/344
>
> Yikes, okay, I've made a mistake somewhere. Sorry about that, I will
> look into this ASAP.
>
> If it's a divide by 0 as your last link indicates, that must mean there
> are possible nodes, but have no CPUs, and those should be skipped. If
> that's the case, the following should fix it, but I'm going to do some
> more qemu testing with various CPU topologies to confirm.
I printed variables from my test host, I think this can help to
investigate the issue:
irq_create_affinity_masks:116: vecs_to_assign 0 ncpus 2 extra_vecs 2
vecs_per_node 0 affv 2 curvec 2 nodes 1
and here is a patch which I use to print them:
diff --git a/kernel/irq/affinity.c b/kernel/irq/affinity.c
index a073a6e..c43c85d 100644
--- a/kernel/irq/affinity.c
+++ b/kernel/irq/affinity.c
@@ -110,7 +110,10 @@ irq_create_affinity_masks(int nvecs, const struct
irq_affinity *affd)
vecs_to_assign = min(vecs_per_node, ncpus);
/* Account for rounding errors */
- extra_vecs = ncpus - vecs_to_assign * (ncpus / vecs_to_assign);
+// extra_vecs = ncpus - vecs_to_assign * (ncpus / vecs_to_assign);
+ extra_vecs = ncpus - vecs_to_assign;
+ printk("%s:%d: vecs_to_assign %d ncpus %d extra_vecs %d
vecs_per_node %d affv %d curvec %d nodes %d\n",
+ __func__, __LINE__, vecs_to_assign, ncpus, extra_vecs,
vecs_per_node, affv, curvec, nodes);
for (v = 0; curvec < last_affv && v < vecs_to_assign;
curvec++, v++) {
>
> ---
> diff --git a/kernel/irq/affinity.c b/kernel/irq/affinity.c
> index d052947..80c45d0 100644
> --- a/kernel/irq/affinity.c
> +++ b/kernel/irq/affinity.c
> @@ -105,6 +105,9 @@ irq_create_affinity_masks(int nvecs, const struct
> irq_affinity *affd)
>
> /* Calculate the number of cpus per vector */
> ncpus = cpumask_weight(nmsk);
> + if (!ncpus)
> + continue;
> +
> vecs_to_assign = min(vecs_per_node, ncpus);
>
> /* Account for rounding errors */
> --
