[patch 20/48] KVM: MMU: increase per-vcpu rmap cache alloc size

From: Greg KH
Date: Fri Sep 04 2009 - 16:19:43 EST

2.6.27-stable review patch. If anyone has any objections, please let us know.

From: Marcelo Tosatti <mtosatti@xxxxxxxxxx>

(cherry picked from commit c41ef344de212bd918f7765af21b5008628c03e0)

The page fault path can use two rmap_desc structures, if:

- walk_addr's dirty pte update allocates one rmap_desc.
- mmu_lock is dropped, sptes are zapped resulting in rmap_desc being
- fetch->mmu_set_spte allocates another rmap_desc.

Increase to 4 for safety.

Signed-off-by: Marcelo Tosatti <mtosatti@xxxxxxxxxx>
Signed-off-by: Avi Kivity <avi@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>
arch/x86/kvm/mmu.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -298,7 +298,7 @@ static int mmu_topup_memory_caches(struc
if (r)
goto out;
r = mmu_topup_memory_cache(&vcpu->arch.mmu_rmap_desc_cache,
- rmap_desc_cache, 1);
+ rmap_desc_cache, 4);
if (r)
goto out;
r = mmu_topup_memory_cache_page(&vcpu->arch.mmu_page_cache, 8);

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