From 5a4c92880493945678315a6df810f7a21f55b985 Mon Sep 17 00:00:00 2001
From: Marcelo Tosatti <mtosatti@redhat.com>
Date: Thu, 3 Jul 2008 18:33:02 -0300
Subject: KVM: mmu_shrink: kvm_mmu_zap_page requires slots_lock to be held
kvm_mmu_zap_page() needs slots lock held (rmap_remove->gfn_to_memslot,
for example).
Since kvm_lock spinlock is held in mmu_shrink(), do a non-blocking
down_read_trylock().
Untested.
Signed-off-by: Avi Kivity <avi@qumranet.com>
---
arch/x86/kvm/mmu.c | 3 +++
1 file changed, 3 insertions(+)
(limited to 'arch/x86')
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 1fd8e3b58cc0..ff7cf632175b 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -1987,6 +1987,8 @@ static int mmu_shrink(int nr_to_scan, gfp_t gfp_mask)
list_for_each_entry(kvm, &vm_list, vm_list) {
int npages;
+ if (!down_read_trylock(&kvm->slots_lock))
+ continue;
spin_lock(&kvm->mmu_lock);
npages = kvm->arch.n_alloc_mmu_pages -
kvm->arch.n_free_mmu_pages;
@@ -1999,6 +2001,7 @@ static int mmu_shrink(int nr_to_scan, gfp_t gfp_mask)
nr_to_scan--;
spin_unlock(&kvm->mmu_lock);
+ up_read(&kvm->slots_lock);
}
if (kvm_freed)
list_move_tail(&kvm_freed->vm_list, &vm_list);
--
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