From 79fd8e706637a5c7c41f9498fe0fbfb437abfdc8 Mon Sep 17 00:00:00 2001 From: Vitaly Kuznetsov Date: Wed, 27 Jan 2016 22:29:34 -0800 Subject: [PATCH] Drivers: hv: vmbus: avoid infinite loop in init_vp_index() When we pick a CPU to use for a new subchannel we try find a non-used one on the appropriate NUMA node, we keep track of them with the primary->alloced_cpus_in_node mask. Under normal circumstances we don't run out of available CPUs but it is possible when we we don't initialize some cpus in Linux, e.g. when we boot with 'nr_cpus=' limitation. Avoid the infinite loop in init_vp_index() by checking that we still have non-used CPUs in the alloced_cpus_in_node mask and resetting it in case we don't. Signed-off-by: Vitaly Kuznetsov Signed-off-by: K. Y. Srinivasan Signed-off-by: Greg Kroah-Hartman --- drivers/hv/channel_mgmt.c | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/drivers/hv/channel_mgmt.c b/drivers/hv/channel_mgmt.c index 107d72f9834d..af1d82eb8ecf 100644 --- a/drivers/hv/channel_mgmt.c +++ b/drivers/hv/channel_mgmt.c @@ -549,6 +549,17 @@ static void init_vp_index(struct vmbus_channel *channel, u16 dev_type) cpumask_of_node(primary->numa_node)); cur_cpu = -1; + + /* + * Normally Hyper-V host doesn't create more subchannels than there + * are VCPUs on the node but it is possible when not all present VCPUs + * on the node are initialized by guest. Clear the alloced_cpus_in_node + * to start over. + */ + if (cpumask_equal(&primary->alloced_cpus_in_node, + cpumask_of_node(primary->numa_node))) + cpumask_clear(&primary->alloced_cpus_in_node); + while (true) { cur_cpu = cpumask_next(cur_cpu, &available_mask); if (cur_cpu >= nr_cpu_ids) { -- 2.20.1