From 5e30a6099b0ba12f5cfc12a3f9cbc0d73d772795 Mon Sep 17 00:00:00 2001
From: Anthony Liguori <aliguori@us.ibm.com>
Date: Mon, 29 Oct 2007 15:15:20 -0500
Subject: [PATCH] --- yaml --- r: 80695 b: refs/heads/master c:
 aab61cc0d28f6fab0c2c9137d95dea54c7dbcf46 h: refs/heads/master i:   80693:
 79caec05295178bdadfbd1f7a7ed9faac174181a   80691:
 b5baf996986a526155d8aad45ef35f20371f50f1   80687:
 e7e657ec98f50bb485840a9e9ce871aa2546a908 v: v3

---
 [refs]                       |  2 +-
 trunk/drivers/kvm/kvm_main.c | 22 ++++++++++++++++++----
 2 files changed, 19 insertions(+), 5 deletions(-)

diff --git a/[refs] b/[refs]
index 23bca2fd1ecf..884f85a4ee0e 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: f78e0e2ee498e8f847500b565792c7d7634dcf54
+refs/heads/master: aab61cc0d28f6fab0c2c9137d95dea54c7dbcf46
diff --git a/trunk/drivers/kvm/kvm_main.c b/trunk/drivers/kvm/kvm_main.c
index ac5ed00e9065..f439e45233f2 100644
--- a/trunk/drivers/kvm/kvm_main.c
+++ b/trunk/drivers/kvm/kvm_main.c
@@ -633,7 +633,10 @@ int kvm_is_visible_gfn(struct kvm *kvm, gfn_t gfn)
 }
 EXPORT_SYMBOL_GPL(kvm_is_visible_gfn);
 
-struct page *gfn_to_page(struct kvm *kvm, gfn_t gfn)
+/*
+ * Requires current->mm->mmap_sem to be held
+ */
+static struct page *__gfn_to_page(struct kvm *kvm, gfn_t gfn)
 {
 	struct kvm_memory_slot *slot;
 	struct page *page[1];
@@ -648,12 +651,10 @@ struct page *gfn_to_page(struct kvm *kvm, gfn_t gfn)
 		return bad_page;
 	}
 
-	down_read(&current->mm->mmap_sem);
 	npages = get_user_pages(current, current->mm,
 				slot->userspace_addr
 				+ (gfn - slot->base_gfn) * PAGE_SIZE, 1,
 				1, 1, page, NULL);
-	up_read(&current->mm->mmap_sem);
 	if (npages != 1) {
 		get_page(bad_page);
 		return bad_page;
@@ -661,6 +662,18 @@ struct page *gfn_to_page(struct kvm *kvm, gfn_t gfn)
 
 	return page[0];
 }
+
+struct page *gfn_to_page(struct kvm *kvm, gfn_t gfn)
+{
+	struct page *page;
+
+	down_read(&current->mm->mmap_sem);
+	page = __gfn_to_page(kvm, gfn);
+	up_read(&current->mm->mmap_sem);
+
+	return page;
+}
+
 EXPORT_SYMBOL_GPL(gfn_to_page);
 
 void kvm_release_page(struct page *page)
@@ -2621,7 +2634,8 @@ static struct page *kvm_vm_nopage(struct vm_area_struct *vma,
 	pgoff = ((address - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
 	if (!kvm_is_visible_gfn(kvm, pgoff))
 		return NOPAGE_SIGBUS;
-	page = gfn_to_page(kvm, pgoff);
+	/* current->mm->mmap_sem is already held so call lockless version */
+	page = __gfn_to_page(kvm, pgoff);
 	if (is_error_page(page)) {
 		kvm_release_page(page);
 		return NOPAGE_SIGBUS;