KVM guest can fail to startup with following trace on host:
qemu-system-x86: page allocation failure: order:4, mode:0x40d0
Call Trace:
dump_stack+0x47/0x67
warn_alloc_failed+0xee/0x150
__alloc_pages_direct_compact+0x14a/0x150
__alloc_pages_nodemask+0x776/0xb80
alloc_kmem_pages+0x3a/0x110
kmalloc_order+0x13/0x50
kmemdup+0x1b/0x40
__kvm_set_memory_region+0x24a/0x9f0 [kvm]
kvm_set_ioapic+0x130/0x130 [kvm]
kvm_set_memory_region+0x21/0x40 [kvm]
kvm_vm_ioctl+0x43f/0x750 [kvm]
Failure happens when attempting to allocate pages for
'struct kvm_memslots', however it doesn't have to be
present in physically contiguous (kmalloc-ed) address
space, change allocation to kvm_kvzalloc() so that
it will be vmalloc-ed when its size is more then a page.
Signed-off-by: Igor Mammedov <imammedo@xxxxxxxxxx>
---
TODO:
- work on follow up patches to allocate space for
actual amount of memory_slots instead of possible maximum.
---
virt/kvm/kvm_main.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index a2214d9..7ed1f5c 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -871,10 +871,10 @@ int __kvm_set_memory_region(struct kvm *kvm,
goto out_free;
}
- slots = kmemdup(kvm->memslots, sizeof(struct kvm_memslots),
- GFP_KERNEL);
+ slots = kvm_kvzalloc(sizeof(struct kvm_memslots));
if (!slots)
goto out_free;
+ memcpy(slots, kvm->memslots, sizeof(struct kvm_memslots));
if ((change == KVM_MR_DELETE) || (change == KVM_MR_MOVE)) {
slot = id_to_memslot(slots, mem->slot);
@@ -936,7 +936,7 @@ int __kvm_set_memory_region(struct kvm *kvm,
return 0;
out_slots:
- kfree(slots);
+ kvfree(slots);
out_free:
kvm_free_physmem_slot(kvm, &new, &old);
out:
--
1.8.3.1
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