From eda2beda835697878e309b6049aa0a3bad051590 Mon Sep 17 00:00:00 2001 From: Lai Jiangshan Date: Tue, 20 Apr 2010 14:29:29 +0800 Subject: [PATCH] KVM: Add missing srcu_read_lock() for kvm_mmu_notifier_release() I got this dmesg due to srcu_read_lock() is missing in kvm_mmu_notifier_release(). =================================================== [ INFO: suspicious rcu_dereference_check() usage. ] --------------------------------------------------- arch/x86/kvm/x86.h:72 invoked rcu_dereference_check() without protection! other info that might help us debug this: rcu_scheduler_active = 1, debug_locks = 0 2 locks held by qemu-system-x86/3100: #0: (rcu_read_lock){.+.+..}, at: [] __mmu_notifier_release+0x38/0xdf #1: (&(&kvm->mmu_lock)->rlock){+.+...}, at: [] kvm_mmu_zap_all+0x21/0x5e [kvm] stack backtrace: Pid: 3100, comm: qemu-system-x86 Not tainted 2.6.34-rc3-22949-gbc8a97a-dirty #2 Call Trace: [] lockdep_rcu_dereference+0xaa/0xb3 [] unalias_gfn+0x56/0xab [kvm] [] gfn_to_memslot+0x16/0x25 [kvm] [] gfn_to_rmap+0x17/0x6e [kvm] [] rmap_remove+0xa0/0x19d [kvm] [] kvm_mmu_zap_page+0x109/0x34d [kvm] [] kvm_mmu_zap_all+0x35/0x5e [kvm] [] kvm_arch_flush_shadow+0x16/0x22 [kvm] [] kvm_mmu_notifier_release+0x15/0x17 [kvm] [] __mmu_notifier_release+0x88/0xdf [] ? __mmu_notifier_release+0x38/0xdf [] ? exit_mm+0xe0/0x115 [] exit_mmap+0x2c/0x17e [] mmput+0x2d/0xd4 [] exit_mm+0x108/0x115 [...] Signed-off-by: Lai Jiangshan Signed-off-by: Avi Kivity --- virt/kvm/kvm_main.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 364daacafb58..c82ae2492634 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -341,7 +341,11 @@ static void kvm_mmu_notifier_release(struct mmu_notifier *mn, struct mm_struct *mm) { struct kvm *kvm = mmu_notifier_to_kvm(mn); + int idx; + + idx = srcu_read_lock(&kvm->srcu); kvm_arch_flush_shadow(kvm); + srcu_read_unlock(&kvm->srcu, idx); } static const struct mmu_notifier_ops kvm_mmu_notifier_ops = { -- 2.20.1