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Message-ID: <20140421132558.GA13608@redhat.com>
Date:	Mon, 21 Apr 2014 15:25:58 +0200
From:	Oleg Nesterov <oleg@...hat.com>
To:	Avi Kivity <avi.kivity@...il.com>, Gleb Natapov <gleb@...nel.org>,
	Paolo Bonzini <pbonzini@...hat.com>
Cc:	Dominik Dingel <dingel@...ux.vnet.ibm.com>,
	Christian Borntraeger <borntraeger@...ibm.com>,
	kvm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH 1/2] KVM: async_pf: kill the unnecessary use_mm/unuse_mm
	async_pf_execute()

async_pf_execute() has no reasons to adopt apf->mm, gup(current, mm)
should work just fine even if current has another or NULL ->mm.

Recently kvm_async_page_present_sync() was added insedie the "use_mm"
section, but it seems that it doesn't need current->mm too.

Signed-off-by: Oleg Nesterov <oleg@...hat.com>
---
 virt/kvm/async_pf.c |    2 --
 1 files changed, 0 insertions(+), 2 deletions(-)

diff --git a/virt/kvm/async_pf.c b/virt/kvm/async_pf.c
index 10df100..0ced4f3 100644
--- a/virt/kvm/async_pf.c
+++ b/virt/kvm/async_pf.c
@@ -80,12 +80,10 @@ static void async_pf_execute(struct work_struct *work)
 
 	might_sleep();
 
-	use_mm(mm);
 	down_read(&mm->mmap_sem);
 	get_user_pages(current, mm, addr, 1, 1, 0, NULL, NULL);
 	up_read(&mm->mmap_sem);
 	kvm_async_page_present_sync(vcpu, apf);
-	unuse_mm(mm);
 
 	spin_lock(&vcpu->async_pf.lock);
 	list_add_tail(&apf->link, &vcpu->async_pf.done);
-- 
1.5.5.1

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