KVM: Fix mmu shrinker error

kvm_mmu_remove_one_alloc_mmu_page() assumes kvm_mmu_zap_page() only reclaims
only one sp, but that's not the case. This will cause mmu shrinker returns
a wrong number. This patch fix the counting error.

Signed-off-by: Gui Jianfeng <guijianfeng@cn.fujitsu.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 9696d654b01faa45afecf14893d7182c160ed5ab..18d2f584945b94bc49a7c8e6c3f72721cca619c6 100644 (file)
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -2902,13 +2902,13 @@ restart:
        kvm_flush_remote_tlbs(kvm);
 }
 
-static void kvm_mmu_remove_one_alloc_mmu_page(struct kvm *kvm)
+static int kvm_mmu_remove_some_alloc_mmu_pages(struct kvm *kvm)
 {
        struct kvm_mmu_page *page;
 
        page = container_of(kvm->arch.active_mmu_pages.prev,
                            struct kvm_mmu_page, link);
-       kvm_mmu_zap_page(kvm, page);
+       return kvm_mmu_zap_page(kvm, page) + 1;
 }
 
 static int mmu_shrink(int nr_to_scan, gfp_t gfp_mask)
@@ -2920,7 +2920,7 @@ static int mmu_shrink(int nr_to_scan, gfp_t gfp_mask)
        spin_lock(&kvm_lock);
 
        list_for_each_entry(kvm, &vm_list, vm_list) {
-               int npages, idx;
+               int npages, idx, freed_pages;
 
                idx = srcu_read_lock(&kvm->srcu);
                spin_lock(&kvm->mmu_lock);
@@ -2928,8 +2928,8 @@ static int mmu_shrink(int nr_to_scan, gfp_t gfp_mask)
                         kvm->arch.n_free_mmu_pages;
                cache_count += npages;
                if (!kvm_freed && nr_to_scan > 0 && npages > 0) {
-                       kvm_mmu_remove_one_alloc_mmu_page(kvm);
-                       cache_count--;
+                       freed_pages = kvm_mmu_remove_some_alloc_mmu_pages(kvm);
+                       cache_count -= freed_pages;
                        kvm_freed = kvm;
                }
                nr_to_scan--;