linux-kernel - [PATCH 1/1] fbdev: hyperv_fb: iounmap() the correct memory when removing a device

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Message-Id: <20250209235252.2987-1-mhklinux@outlook.com>
Date: Sun,  9 Feb 2025 15:52:52 -0800
From: mhkelley58@...il.com
To: haiyangz@...rosoft.com,
	wei.liu@...nel.org,
	decui@...rosoft.com,
	deller@....de,
	weh@...rosoft.com
Cc: dri-devel@...ts.freedesktop.org,
	linux-fbdev@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	linux-hyperv@...r.kernel.org
Subject: [PATCH 1/1] fbdev: hyperv_fb: iounmap() the correct memory when removing a device

From: Michael Kelley <mhklinux@...look.com>

When a Hyper-V framebuffer device is removed, or the driver is unbound
from a device, any allocated and/or mapped memory must be released. In
particular, MMIO address space that was mapped to the framebuffer must
be unmapped. Current code unmaps the wrong address, resulting in an
error like:

[ 4093.980597] iounmap: bad address 00000000c936c05c

followed by a stack dump.

Commit d21987d709e8 ("video: hyperv: hyperv_fb: Support deferred IO for
Hyper-V frame buffer driver") changed the kind of address stored in
info->screen_base, and the iounmap() call in hvfb_putmem() was not
updated accordingly.

Fix this by updating hvfb_putmem() to unmap the correct address.

Fixes: d21987d709e8 ("video: hyperv: hyperv_fb: Support deferred IO for Hyper-V frame buffer driver")
Signed-off-by: Michael Kelley <mhklinux@...look.com>
---
 drivers/video/fbdev/hyperv_fb.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/video/fbdev/hyperv_fb.c b/drivers/video/fbdev/hyperv_fb.c
index 7fdb5edd7e2e..363e4ccfcdb7 100644
--- a/drivers/video/fbdev/hyperv_fb.c
+++ b/drivers/video/fbdev/hyperv_fb.c
@@ -1080,7 +1080,7 @@ static void hvfb_putmem(struct hv_device *hdev, struct fb_info *info)

 	if (par->need_docopy) {
 		vfree(par->dio_vp);
-		iounmap(info->screen_base);
+		iounmap(par->mmio_vp);
 		vmbus_free_mmio(par->mem->start, screen_fb_size);
 	} else {
 		hvfb_release_phymem(hdev, info->fix.smem_start,
-- 
2.25.1