linux-kernel - [PATCH 4.17 20/67] vmw_balloon: fix inflation with batching

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Message-Id: <20180716073446.256595404@linuxfoundation.org>
Date:   Mon, 16 Jul 2018 09:34:49 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Xavier Deguillard <xdeguillard@...are.com>,
        Nadav Amit <namit@...are.com>
Subject: [PATCH 4.17 20/67] vmw_balloon: fix inflation with batching

4.17-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Nadav Amit <namit@...are.com>

commit 90d72ce079791399ac255c75728f3c9e747b093d upstream.

Embarrassingly, the recent fix introduced worse problem than it solved,
causing the balloon not to inflate. The VM informed the hypervisor that
the pages for lock/unlock are sitting in the wrong address, as it used
the page that is used the uninitialized page variable.

Fixes: b23220fe054e9 ("vmw_balloon: fixing double free when batching mode is off")
Cc: stable@...r.kernel.org
Reviewed-by: Xavier Deguillard <xdeguillard@...are.com>
Signed-off-by: Nadav Amit <namit@...are.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/misc/vmw_balloon.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/drivers/misc/vmw_balloon.c
+++ b/drivers/misc/vmw_balloon.c
@@ -467,7 +467,7 @@ static int vmballoon_send_batched_lock(s
 		unsigned int num_pages, bool is_2m_pages, unsigned int *target)
 {
 	unsigned long status;
-	unsigned long pfn = page_to_pfn(b->page);
+	unsigned long pfn = PHYS_PFN(virt_to_phys(b->batch_page));
 
 	STATS_INC(b->stats.lock[is_2m_pages]);
 
@@ -515,7 +515,7 @@ static bool vmballoon_send_batched_unloc
 		unsigned int num_pages, bool is_2m_pages, unsigned int *target)
 {
 	unsigned long status;
-	unsigned long pfn = page_to_pfn(b->page);
+	unsigned long pfn = PHYS_PFN(virt_to_phys(b->batch_page));
 
 	STATS_INC(b->stats.unlock[is_2m_pages]);