linux-kernel - [PATCH] vmw_balloon: fix inflation with batching

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Date:   Mon, 2 Jul 2018 19:27:13 -0700
From:   Nadav Amit <namit@...are.com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
CC:     <linux-kernel@...r.kernel.org>, Arnd Bergmann <arnd@...db.de>,
        <xdeguillard@...are.com>, Nadav Amit <namit@...are.com>,
        <stable@...r.kernel.org>
Subject: [PATCH] vmw_balloon: fix inflation with batching

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

diff --git a/drivers/misc/vmw_balloon.c b/drivers/misc/vmw_balloon.c
index efd733472a35..56c6f79a5c5a 100644
--- a/drivers/misc/vmw_balloon.c
+++ b/drivers/misc/vmw_balloon.c
@@ -467,7 +467,7 @@ static int vmballoon_send_batched_lock(struct vmballoon *b,
 		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_unlock(struct vmballoon *b,
 		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]);
 
-- 
2.17.1