[PATCH 4.4 36/91] drm/ast: Fix incorrect free on ioregs

[Greg Kroah-Hartman]

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

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

From: Sam Bobroff <sbobr...@linux.ibm.com>

commit dc25ab067645eabd037f1a23d49a666f9e0b8c68 upstream.

If the platform has no IO space, ioregs is placed next to the already
allocated regs. In this case, it should not be separately freed.

This prevents a kernel warning from __vunmap "Trying to vfree()
nonexistent vm area" when unloading the driver.

Fixes: 0dd68309b9c5 ("drm/ast: Try to use MMIO registers when PIO isn't 
supported")

Signed-off-by: Sam Bobroff <sbobr...@linux.ibm.com>
Cc: <sta...@vger.kernel.org>
Signed-off-by: Dave Airlie <airl...@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>

---
 drivers/gpu/drm/ast/ast_main.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/drivers/gpu/drm/ast/ast_main.c
+++ b/drivers/gpu/drm/ast/ast_main.c
@@ -557,7 +557,8 @@ int ast_driver_unload(struct drm_device
        drm_mode_config_cleanup(dev);
 
        ast_mm_fini(ast);
-       pci_iounmap(dev->pdev, ast->ioregs);
+       if (ast->ioregs != ast->regs + AST_IO_MM_OFFSET)
+               pci_iounmap(dev->pdev, ast->ioregs);
        pci_iounmap(dev->pdev, ast->regs);
        kfree(ast);
        return 0;