KVM: Retry sleeping allocation if atomic allocation fails

This avoids -ENOMEM under memory pressure.

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

1 files changed, 21 insertions, 5 deletions

diff --git a/drivers/kvm/mmu.c b/drivers/kvm/mmu.c
index a368ea8297f3..c814394a966d 100644
--- 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);