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SubjectRe: [Bug 206175] Fedora >= 5.4 kernels instantly freeze on boot without producing any display output
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On 3/11/20 3:47 PM, Christoph Hellwig wrote:
> And actually one more idea after looking at what slab interactions
> could exist. platform_device_register_full frees the dma_mask
> unconditionally, even if it didn't allocated it, which might lead
> to weird memory corruption if we hit the failure path. So let's try
> something like this, replacing the earlier patch in that file.
>
> diff --git a/drivers/base/platform.c b/drivers/base/platform.c
> index b230beb6ccb4..04080a8d94e2 100644
> --- a/drivers/base/platform.c
> +++ b/drivers/base/platform.c
> @@ -632,19 +632,6 @@ struct platform_device *platform_device_register_full(
> pdev->dev.of_node_reused = pdevinfo->of_node_reused;
>
> if (pdevinfo->dma_mask) {
> - /*
> - * This memory isn't freed when the device is put,
> - * I don't have a nice idea for that though. Conceptually
> - * dma_mask in struct device should not be a pointer.
> - * See http://thread.gmane.org/gmane.linux.kernel.pci/9081
> - */
> - pdev->dev.dma_mask =
> - kmalloc(sizeof(*pdev->dev.dma_mask), GFP_KERNEL);
> - if (!pdev->dev.dma_mask)
> - goto err;
> -
> - kmemleak_ignore(pdev->dev.dma_mask);
> -
> *pdev->dev.dma_mask = pdevinfo->dma_mask;
> pdev->dev.coherent_dma_mask = pdevinfo->dma_mask;
> }
> @@ -670,7 +657,6 @@ struct platform_device *platform_device_register_full(
> if (ret) {
> err:
> ACPI_COMPANION_SET(&pdev->dev, NULL);
> - kfree(pdev->dev.dma_mask);
> platform_device_put(pdev);
> return ERR_PTR(ret);
> }
>

With this patch the system works (I haven't created an initrd, so it
doesn't completely boot and panics on not being able to mount root fs
but that's expected).

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