From: Lai Jiangshan <[email protected]>
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: [<ffffffff810d73dc>]
__mmu_notifier_release+0x38/0xdf
#1: (&(&kvm->mmu_lock)->rlock){+.+...}, at: [<ffffffffa0130a6a>]
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:
[<ffffffff8106afd9>] lockdep_rcu_dereference+0xaa/0xb3
[<ffffffffa0123a89>] unalias_gfn+0x56/0xab [kvm]
[<ffffffffa0119600>] gfn_to_memslot+0x16/0x25 [kvm]
[<ffffffffa012ffca>] gfn_to_rmap+0x17/0x6e [kvm]
[<ffffffffa01300c1>] rmap_remove+0xa0/0x19d [kvm]
[<ffffffffa0130649>] kvm_mmu_zap_page+0x109/0x34d [kvm]
[<ffffffffa0130a7e>] kvm_mmu_zap_all+0x35/0x5e [kvm]
[<ffffffffa0122870>] kvm_arch_flush_shadow+0x16/0x22 [kvm]
[<ffffffffa01189e0>] kvm_mmu_notifier_release+0x15/0x17 [kvm]
[<ffffffff810d742c>] __mmu_notifier_release+0x88/0xdf
[<ffffffff810d73dc>] ? __mmu_notifier_release+0x38/0xdf
[<ffffffff81040848>] ? exit_mm+0xe0/0x115
[<ffffffff810c2cb0>] exit_mmap+0x2c/0x17e
[<ffffffff8103c472>] mmput+0x2d/0xd4
[<ffffffff81040870>] exit_mm+0x108/0x115
[...]
Signed-off-by: Lai Jiangshan <[email protected]>
Signed-off-by: Avi Kivity <[email protected]>
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 3725605..d6351a3 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 = {
--
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