From: Marcelo Tosatti <mtosatti@redhat.com>
Date: Wed, 16 Apr 2008 20:19:06 +0000 (-0300)
Subject: KVM: MMU: kvm_pv_mmu_op should not take mmap_sem
X-Git-Tag: v2.6.26-rc1~1028^2~1
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=960b3991698872f68f09d51f4c2794ad484fe1fd;p=platform%2Fkernel%2Flinux-3.10.git

KVM: MMU: kvm_pv_mmu_op should not take mmap_sem

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>
---

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;
 }