Patch "xen/gntdevt: Fix race condition in gntdev_release()" has been added to the 3.14-stable tree

This is a note to let you know that I've just added the patch titled

xen/gntdevt: Fix race condition in gntdev_release()

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:
xen-gntdevt-fix-race-condition-in-gntdev_release.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 <[email protected]> know about it.

From: =?UTF-8?q?Marek=20Marczykowski-G=C3=B3recki?=
<[email protected]>
Date: Fri, 26 Jun 2015 03:28:24 +0200
Subject: xen/gntdevt: Fix race condition in gntdev_release()
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From: =?UTF-8?q?Marek=20Marczykowski-G=C3=B3recki?=

commit 30b03d05e07467b8c6ec683ea96b5bffcbcd3931 upstream.

While gntdev_release() is called the MMU notifier is still registered and can traverse priv->maps list even if no pages are mapped (which is the case -- gntdev_release() is called after all). But gntdev_release() will clear that list, so make sure that only one of those things happens at the same time.

---
 drivers/xen/gntdev.c |    2 ++
 1 file changed, 2 insertions(+)

@@ -529,12 +529,14 @@ static int gntdev_release(struct inode *
 
 	pr_debug("priv %p\n", priv);
 
+	mutex_lock(&priv->lock);
 	while (!list_empty(&priv->maps)) {
 		map = list_entry(priv->maps.next, struct grant_map, next);
 		list_del(&map->next);
 		gntdev_put_map(NULL /* already removed */, map);
 	}
 	WARN_ON(!list_empty(&priv->freeable_maps));
+	mutex_unlock(&priv->lock);
 
 	if (use_ptemod)
 		mmu_notifier_unregister(&priv->mn, priv->mm);

Patches currently in stable-queue which might be from [email protected] are

queue-3.14/xen-gntdevt-fix-race-condition-in-gntdev_release.patch