diff mbox series

[RFC,v2,4/4] KVM: enforce NR_IOBUS_DEVS limit if kmemcg is disabled

Message ID c5426ed44a9ab9fe2a0d4a6a4dee30b3be30b0e3.1611850291.git.eafanasova@gmail.com (mailing list archive)
State New, archived
Headers show
Series Introduce MMIO/PIO dispatch file descriptors (ioregionfd) | expand

Commit Message

Elena Afanasova Jan. 28, 2021, 6:32 p.m. UTC 
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 <eafanasova@gmail.com>
---
 virt/kvm/kvm_main.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)
diff mbox series

Patch

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);