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Subject[PATCH 31/31] KVM: MMU: kvm_pv_mmu_op should not take mmap_sem
Date
From: Marcelo Tosatti <mtosatti@redhat.com>

kvm_pv_mmu_op should not take mmap_sem. All gfn_to_page() callers down
in the MMU processing will take it if necessary, so as it is it can
deadlock.

Apparently a leftover from the days before slots_lock.

Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>
---
arch/x86/kvm/mmu.c | 3 ---
1 files changed, 0 insertions(+), 3 deletions(-)
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 078a7f1..2ad6f54 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -2173,8 +2173,6 @@ int kvm_pv_mmu_op(struct kvm_vcpu *vcpu, unsigned long bytes,
int r;
struct kvm_pv_mmu_op_buffer buffer;

- down_read(&current->mm->mmap_sem);
-
buffer.ptr = buffer.buf;
buffer.len = min_t(unsigned long, bytes, sizeof buffer.buf);
buffer.processed = 0;
@@ -2194,7 +2192,6 @@ int kvm_pv_mmu_op(struct kvm_vcpu *vcpu, unsigned long bytes,
r = 1;
out:
*ret = buffer.processed;
- up_read(&current->mm->mmap_sem);
return r;
}

--
1.5.5


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