linux-kernel - Re: [Bug 206175] Fedora >= 5.4 kernels instantly freeze on boot without producing any display output

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Date:   Wed, 11 Mar 2020 16:02:39 +0000
From:   "Artem S. Tashkinov" <aros@....com>
To:     Christoph Hellwig <hch@....de>
Cc:     Linus Torvalds <torvalds@...ux-foundation.org>,
        linux-kernel@...r.kernel.org,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        iommu@...ts.linux-foundation.org
Subject: Re: [Bug 206175] Fedora >= 5.4 kernels instantly freeze on boot
 without producing any display output



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).