[RFC v2 4/4] KVM: enforce NR_IOBUS_DEVS limit if kmemcg is disabled
From: Elena Afanasova <hidden>
Date: 2021-01-28 18:50:16
Subsystem:
kernel virtual machine (kvm), the rest · Maintainers:
Paolo Bonzini, Linus Torvalds
ioregionfd relies on kmemcg in order to limit the amount of kernel memory that userspace can consume. Enforce NR_IOBUS_DEVS hardcoded limit in case kmemcg is disabled. Signed-off-by: Elena Afanasova <redacted> --- virt/kvm/kvm_main.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-)
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 096504a6cc62..74bedb7272e6 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c@@ -4352,9 +4352,12 @@ int kvm_io_bus_register_dev(struct kvm *kvm, enum kvm_bus bus_idx, gpa_t addr, if (!bus) return -ENOMEM; - /* exclude ioeventfd which is limited by maximum fd */ - if (bus->dev_count - bus->ioeventfd_count > NR_IOBUS_DEVS - 1) - return -ENOSPC; + /* enforce hard limit if kmemcg is disabled and + * exclude ioeventfd which is limited by maximum fd + */ + if (!memcg_kmem_enabled()) + if (bus->dev_count - bus->ioeventfd_count > NR_IOBUS_DEVS - 1) + return -ENOSPC; new_bus = kmalloc(struct_size(bus, range, bus->dev_count + 1), GFP_KERNEL_ACCOUNT);
--
2.25.1