Re: [PATCH v1] virtio-mem: only mark the device ready in kdump mode with vmcore support

["David Hildenbrand (Arm)" <david@kernel.org>]

On 10/16/26 04:35, Yuho Choi wrote:
> virtio_mem_init_kdump() marks the device DRIVER_OK before it checks for
> CONFIG_PROC_VMCORE.  Without vmcore support it then fails with -EBUSY,
> and virtio_mem_probe() deletes the virtqueue on that error path without
> resetting the device first, so the device is left believing the driver
> is ready while its queue points at memory that has been freed.
> 
> Before commit a9403425b3cf ("virtio-mem: mark device ready before
> registering callbacks in kdump mode"), virtio_mem_probe() called
> virtio_device_ready() only after virtio_mem_init() had succeeded, so this
> path never exposed a ready device.
> 
> Move virtio_device_ready() into the CONFIG_PROC_VMCORE branch, right
> before the vmcore callbacks that need it are registered, so the -EBUSY
> path never sets DRIVER_OK.
> 
> Fixes: a9403425b3cf ("virtio-mem: mark device ready before registering callbacks in kdump mode")
> Cc: stable@vger.kernel.org

Which kdump kernel exists that does not enable CONFIG_PROC_VMCORE?

IOW, why should this be stable material?


> Signed-off-by: Yuho Choi <oss.patchbox@gmail.com>
> ---
>  drivers/virtio/virtio_mem.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/virtio/virtio_mem.c b/drivers/virtio/virtio_mem.c
> index e18dd736f2ec..b28d2da7d5b6 100644
> --- a/drivers/virtio/virtio_mem.c
> +++ b/drivers/virtio/virtio_mem.c
> @@ -2817,9 +2817,9 @@ static int virtio_mem_vmcore_get_device_ram(struct vmcore_cb *cb,
>  
>  static int virtio_mem_init_kdump(struct virtio_mem *vm)
>  {
> +#ifdef CONFIG_PROC_VMCORE
>  	/* We must be prepared to receive a callback immediately. */
>  	virtio_device_ready(vm->vdev);
> -#ifdef CONFIG_PROC_VMCORE
>  	dev_info(&vm->vdev->dev, "memory hot(un)plug disabled in kdump kernel\n");
>  	vm->vmcore_cb.pfn_is_ram = virtio_mem_vmcore_pfn_is_ram;
>  #ifdef CONFIG_PROC_VMCORE_DEVICE_RAM

LGTM, but I am pretty sure it does not make any difference in practice?

-- 
Cheers,

David