[PATCH] KVM: Fix mmu shrinker error

[PATCH] KVM: Fix mmu shrinker error

[Gui Jianfeng]

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>
---
 arch/x86/kvm/mmu.c |   10 +++++-----
 1 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 7a17db1..c97368e 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -2914,13 +2914,13 @@ 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)
@@ -2932,7 +2932,7 @@ 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);
@@ -2940,8 +2940,8 @@ 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--;
-- 
1.6.5.2

Re: [PATCH] KVM: Fix mmu shrinker error

[Marcelo Tosatti]

On Tue, Apr 27, 2010 at 10:39:49AM +0800, Gui Jianfeng wrote:
> 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>
> ---
>  arch/x86/kvm/mmu.c |   10 +++++-----
>  1 files changed, 5 insertions(+), 5 deletions(-)

Applied, thanks.