From mboxrd@z Thu Jan 1 00:00:00 1970 From: Marcelo Tosatti Subject: KVM: MMU: kvm_pv_mmu_op should not take mmap_sem Date: Wed, 16 Apr 2008 17:19:06 -0300 Message-ID: <20080416201906.GA3551@dmt> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: kvm-devel To: Avi Kivity Return-path: Content-Disposition: inline List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: kvm-devel-bounces@lists.sourceforge.net Errors-To: kvm-devel-bounces@lists.sourceforge.net List-Id: kvm.vger.kernel.org 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 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(¤t->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(¤t->mm->mmap_sem); return r; } ------------------------------------------------------------------------- This SF.net email is sponsored by the 2008 JavaOne(SM) Conference Don't miss this year's exciting event. There's still time to save $100. Use priority code J8TL2D2. http://ad.doubleclick.net/clk;198757673;13503038;p?http://java.sun.com/javaone