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Message-ID: <1558558075.2470.2.camel@suse.com>
Subject: Re: [RFC PATCH] usb: host: xhci: allow __GFP_FS in dma allocation
From:   Oliver Neukum <oneukum@suse.com>
To:     Alan Stern <stern@rowland.harvard.edu>
Cc:     Jaewon Kim <jaewon31.kim@gmail.com>,
        Christoph Hellwig <hch@infradead.org>, linux-mm@kvack.org,
        gregkh@linuxfoundation.org, Jaewon Kim <jaewon31.kim@samsung.com>,
        m.szyprowski@samsung.com, ytk.lee@samsung.com,
        linux-kernel@vger.kernel.org, linux-usb@vger.kernel.org
Date:   Wed, 22 May 2019 22:47:55 +0200
In-Reply-To: <Pine.LNX.4.44L0.1905221055190.1410-100000@iolanthe.rowland.org>
References: <Pine.LNX.4.44L0.1905221055190.1410-100000@iolanthe.rowland.org>
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On Mi, 2019-05-22 at 10:56 -0400, Alan Stern wrote:
> On Wed, 22 May 2019, Oliver Neukum wrote:
> 
> > I agree with the problem, but I fail to see why this issue would be
> > specific to USB. Shouldn't this be done in the device core layer?
> 
> Only for drivers that are on the block-device writeback path.  The 
> device core doesn't know which drivers these are.

Neither does USB know. It is very hard to predict or even tell which
devices are block device drivers. I think we must assume that
any device may be affected.

	Regards
		Oliver