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Commit 74496134 authored by Igor Mammedov's avatar Igor Mammedov Committed by Marcelo Tosatti
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kvm: avoid page allocation failure in kvm_set_memory_region() 



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: default avatarIgor Mammedov <imammedo@redhat.com>
Signed-off-by: default avatarMarcelo Tosatti <mtosatti@redhat.com>
parent c806a6ad

virt/kvm/kvm_main.c

+7 −7
Original line number Diff line number Diff line
@@ -471,7 +471,7 @@ static struct kvm *kvm_create_vm(unsigned long type) 
	BUILD_BUG_ON(KVM_MEM_SLOTS_NUM > SHRT_MAX);



	r = -ENOMEM;

	kvm->memslots = kzalloc(sizeof(struct kvm_memslots), GFP_KERNEL);

	kvm->memslots = kvm_kvzalloc(sizeof(struct kvm_memslots));

	if (!kvm->memslots)

		goto out_err_no_srcu;
@@ -522,7 +522,7 @@ static struct kvm *kvm_create_vm(unsigned long type) 
out_err_no_disable:

	for (i = 0; i < KVM_NR_BUSES; i++)

		kfree(kvm->buses[i]);

	kfree(kvm->memslots);

	kvfree(kvm->memslots);

	kvm_arch_free_vm(kvm);

	return ERR_PTR(r);

}
@@ -578,7 +578,7 @@ static void kvm_free_physmem(struct kvm *kvm) 
	kvm_for_each_memslot(memslot, slots)

		kvm_free_physmem_slot(kvm, memslot, NULL);



	kfree(kvm->memslots);

	kvfree(kvm->memslots);

}



static void kvm_destroy_devices(struct kvm *kvm)
@@ -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);
@@ -917,7 +917,7 @@ int __kvm_set_memory_region(struct kvm *kvm, 
	kvm_arch_commit_memory_region(kvm, mem, &old, change);



	kvm_free_physmem_slot(kvm, &old, &new);

	kfree(old_memslots);

	kvfree(old_memslots);



	/*

	 * IOMMU mapping:  New slots need to be mapped.  Old slots need to be
@@ -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: