commit 960b3991698872f68f09d51f4c2794ad484fe1fd
author Marcelo Tosatti <mtosatti@redhat.com> Wed Apr 16 17:19:06 2008 -0300
committer Avi Kivity <avi@qumranet.com> Sun Apr 27 18:21:45 2008 +0300
tree a5b2d84dfb0f7009538c1c07ca5e244da2be3956
parent 1336028b9a1fb33537eab8caec66e812eb8cad63

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>

arch/x86/kvm/mmu.c

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 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 @@
 	r = 1;
 out:
 	*ret = buffer.processed;
-	up_read(&current->mm->mmap_sem);
 	return r;
 }