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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>
This commit is contained in:
Marcelo Tosatti 2008-07-03 18:33:02 -03:00 committed by Avi Kivity
parent 7e37c2998a
commit 5a4c928804
1 changed files with 3 additions and 0 deletions
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3
arch/x86/kvm/mmu.c
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@ -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) { list_for_each_entry(kvm, &vm_list, vm_list) {
int npages; int npages;
if (!down_read_trylock(&kvm->slots_lock))
continue;
spin_lock(&kvm->mmu_lock); spin_lock(&kvm->mmu_lock);
npages = kvm->arch.n_alloc_mmu_pages - npages = kvm->arch.n_alloc_mmu_pages -
kvm->arch.n_free_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--; nr_to_scan--;
spin_unlock(&kvm->mmu_lock); spin_unlock(&kvm->mmu_lock);
up_read(&kvm->slots_lock);
} }
if (kvm_freed) if (kvm_freed)
list_move_tail(&kvm_freed->vm_list, &vm_list); list_move_tail(&kvm_freed->vm_list, &vm_list);