Re: [PATCH 1/1] fbdev: hyperv_fb: iounmap() the correct memory when removing a device
From: Saurabh Singh Sengar <ssengar@linux.microsoft.com>
Date: 2025-02-10 12:40:44
Also in:
dri-devel, linux-fbdev, lkml
On Sun, Feb 09, 2025 at 03:52:52PM -0800, mhkelley58@gmail.com wrote:
quoted hunk ↗ jump to hunk
From: Michael Kelley <redacted> 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 <redacted> --- 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
Thanks for fixing this: Reviewed-by: Saurabh Sengar <ssengar@linux.microsoft.com> While we are at it, I want to mention that I also observed below WARN while removing the hyperv_fb, but that needs a separate fix. [ 44.111220] WARNING: CPU: 35 PID: 1882 at drivers/video/fbdev/core/fb_info.c:70 framebuffer_release+0x2c/0x40 < snip > [ 44.111289] Call Trace: [ 44.111290] <TASK> [ 44.111291] ? show_regs+0x6c/0x80 [ 44.111295] ? __warn+0x8d/0x150 [ 44.111298] ? framebuffer_release+0x2c/0x40 [ 44.111300] ? report_bug+0x182/0x1b0 [ 44.111303] ? handle_bug+0x6e/0xb0 [ 44.111306] ? exc_invalid_op+0x18/0x80 [ 44.111308] ? asm_exc_invalid_op+0x1b/0x20 [ 44.111311] ? framebuffer_release+0x2c/0x40 [ 44.111313] ? hvfb_remove+0x86/0xa0 [hyperv_fb] [ 44.111315] vmbus_remove+0x24/0x40 [hv_vmbus] [ 44.111323] device_remove+0x40/0x80 [ 44.111325] device_release_driver_internal+0x20b/0x270 [ 44.111327] ? bus_find_device+0xb3/0xf0 - Saurabh