This is a note to let you know that I've just added the patch titled
KVM: async_pf: mm->mm_users can not pin apf->mm
to the 3.14-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
kvm-async_pf-mm-mm_users-can-not-pin-apf-mm.patch
and it can be found in the queue-3.14 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 41c22f626254b9dc0376928cae009e73d1b6a49a Mon Sep 17 00:00:00 2001
From: Oleg Nesterov <oleg@xxxxxxxxxx>
Date: Mon, 21 Apr 2014 15:26:01 +0200
Subject: KVM: async_pf: mm->mm_users can not pin apf->mm
From: Oleg Nesterov <oleg@xxxxxxxxxx>
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@xxxxxxxxxx>
Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
virt/kvm/async_pf.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
--- a/virt/kvm/async_pf.c
+++ b/virt/kvm/async_pf.c
@@ -85,7 +85,7 @@ static void async_pf_execute(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
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 *
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 *
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;
}
Patches currently in stable-queue which might be from oleg@xxxxxxxxxx are
queue-3.14/kvm-async_pf-mm-mm_users-can-not-pin-apf-mm.patch
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