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Date:   Thu, 14 May 2020 13:58:29 +0200
From:   Christoph Hellwig <hch@lst.de>
To:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc:     linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org,
        Christoph Hellwig <hch@lst.de>,
        Hillf Danton <hdanton@sina.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Jeremy Linton <jeremy.linton@arm.com>,
        syzbot+353be47c9ce21b68b7ed@syzkaller.appspotmail.com,
        stable <stable@vger.kernel.org>
Subject: Re: [PATCH] USB: usbfs: fix mmap dma mismatch
Message-ID: <20200514115829.GA15995@lst.de>
References: <20200514112711.1858252-1-gregkh@linuxfoundation.org>
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On Thu, May 14, 2020 at 01:27:11PM +0200, Greg Kroah-Hartman wrote:
> +	if (hcd->localmem_pool || !hcd_uses_dma(hcd)) {
> +		if (remap_pfn_range(vma, vma->vm_start,
> +				    virt_to_phys(usbm->mem) >> PAGE_SHIFT,
> +				    size, vma->vm_page_prot) < 0) {
> +			dec_usb_memory_use_count(usbm, &usbm->vma_use_count);
> +			return -EAGAIN;
> +		}
> +	} else {
> +		if (dma_mmap_coherent(hcd->self.sysdev, vma, mem, dma_handle,
> +				      size)) {
> +			dec_usb_memory_use_count(usbm, &usbm->vma_use_count);
> +			return -EAGAIN;
> +		}

What about a goto label to share the error handling path?

Otherwise looks good:

Reviewed-by: Christoph Hellwig <hch@lst.de>