KVM: Retry sleeping allocation if atomic allocation fails

This avoids -ENOMEM under memory pressure.

Signed-off-by: Avi Kivity <avi@qumranet.com>

diff --git a/drivers/kvm/mmu.c b/drivers/kvm/mmu.c
index a368ea8..c814394 100644 (file)
--- a/drivers/kvm/mmu.c
+++ b/drivers/kvm/mmu.c
@@ -199,14 +199,15 @@ static int is_rmap_pte(u64 pte)
 }
 
 static int mmu_topup_memory_cache(struct kvm_mmu_memory_cache *cache,
-                                 struct kmem_cache *base_cache, int min)
+                                 struct kmem_cache *base_cache, int min,
+                                 gfp_t gfp_flags)
 {
        void *obj;
 
        if (cache->nobjs >= min)
                return 0;
        while (cache->nobjs < ARRAY_SIZE(cache->objects)) {
-               obj = kmem_cache_zalloc(base_cache, GFP_NOWAIT);
+               obj = kmem_cache_zalloc(base_cache, gfp_flags);
                if (!obj)
                        return -ENOMEM;
                cache->objects[cache->nobjs++] = obj;
@@ -220,20 +221,35 @@ static void mmu_free_memory_cache(struct kvm_mmu_memory_cache *mc)
                kfree(mc->objects[--mc->nobjs]);
 }
 
-static int mmu_topup_memory_caches(struct kvm_vcpu *vcpu)
+static int __mmu_topup_memory_caches(struct kvm_vcpu *vcpu, gfp_t gfp_flags)
 {
        int r;
 
        r = mmu_topup_memory_cache(&vcpu->mmu_pte_chain_cache,
-                                  pte_chain_cache, 4);
+                                  pte_chain_cache, 4, gfp_flags);
        if (r)
                goto out;
        r = mmu_topup_memory_cache(&vcpu->mmu_rmap_desc_cache,
-                                  rmap_desc_cache, 1);
+                                  rmap_desc_cache, 1, gfp_flags);
 out:
        return r;
 }
 
+static int mmu_topup_memory_caches(struct kvm_vcpu *vcpu)
+{
+       int r;
+
+       r = __mmu_topup_memory_caches(vcpu, GFP_NOWAIT);
+       if (r < 0) {
+               spin_unlock(&vcpu->kvm->lock);
+               kvm_arch_ops->vcpu_put(vcpu);
+               r = __mmu_topup_memory_caches(vcpu, GFP_KERNEL);
+               kvm_arch_ops->vcpu_load(vcpu);
+               spin_lock(&vcpu->kvm->lock);
+       }
+       return r;
+}
+
 static void mmu_free_memory_caches(struct kvm_vcpu *vcpu)
 {
        mmu_free_memory_cache(&vcpu->mmu_pte_chain_cache);