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authorOleg Nesterov <oleg@redhat.com>2014-04-21 15:26:01 +0200
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2014-05-13 13:32:47 +0200
commit9e66614b8c36b8d96bf7b271a3eacada1e4c589d (patch)
treec868314808f12e9ef2017a4f4a518fcc9ed31234
parente8c827bae71da914b094756f93d3b6d30ce85a89 (diff)
KVM: async_pf: mm->mm_users can not pin apf->mm
commit 41c22f626254b9dc0376928cae009e73d1b6a49a upstream. get_user_pages(mm) is simply wrong if mm->mm_users == 0 and exit_mmap/etc was already called (or is in progress), mm->mm_count can only pin mm->pgd and mm_struct itself. Change kvm_setup_async_pf/async_pf_execute to inc/dec mm->mm_users. kvm_create_vm/kvm_destroy_vm play with ->mm_count too but this case looks fine at first glance, it seems that this ->mm is only used to verify that current->mm == kvm->mm. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--virt/kvm/async_pf.c8
1 files changed, 4 insertions, 4 deletions
diff --git a/virt/kvm/async_pf.c b/virt/kvm/async_pf.c
index 8631d9c14320..f2c80d5451c3 100644
--- a/virt/kvm/async_pf.c
+++ b/virt/kvm/async_pf.c
@@ -85,7 +85,7 @@ static void async_pf_execute(struct work_struct *work)
if (waitqueue_active(&vcpu->wq))
wake_up_interruptible(&vcpu->wq);
- mmdrop(mm);
+ mmput(mm);
kvm_put_kvm(vcpu->kvm);
}
@@ -98,7 +98,7 @@ void kvm_clear_async_pf_completion_queue(struct kvm_vcpu *vcpu)
typeof(*work), queue);
list_del(&work->queue);
if (cancel_work_sync(&work->work)) {
- mmdrop(work->mm);
+ mmput(work->mm);
kvm_put_kvm(vcpu->kvm); /* == work->vcpu->kvm */
kmem_cache_free(async_pf_cache, work);
}
@@ -162,7 +162,7 @@ int kvm_setup_async_pf(struct kvm_vcpu *vcpu, gva_t gva, gfn_t gfn,
work->addr = gfn_to_hva(vcpu->kvm, gfn);
work->arch = *arch;
work->mm = current->mm;
- atomic_inc(&work->mm->mm_count);
+ atomic_inc(&work->mm->mm_users);
kvm_get_kvm(work->vcpu->kvm);
/* this can't really happen otherwise gfn_to_pfn_async
@@ -180,7 +180,7 @@ int kvm_setup_async_pf(struct kvm_vcpu *vcpu, gva_t gva, gfn_t gfn,
return 1;
retry_sync:
kvm_put_kvm(work->vcpu->kvm);
- mmdrop(work->mm);
+ mmput(work->mm);
kmem_cache_free(async_pf_cache, work);
return 0;
}