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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
Subject: Re: [RFC PATCH] usb: host: xhci: allow __GFP_FS in dma allocation
Date: Wed, 22 May 2019 08:31:42 +0200	[thread overview]
Message-ID: <1558506702.12672.28.camel@suse.com> (raw)
In-Reply-To: <Pine.LNX.4.44L0.1905210950170.1634-100000@iolanthe.rowland.org>

On Di, 2019-05-21 at 10:00 -0400, Alan Stern wrote:
> 
> Changing configurations amounts to much the same as disconnecting,
> because both operations destroy all the existing interfaces.
> 
> Disconnect can arise in two different ways.
> 
>         Physical hot-unplug: All I/O operations will fail.
> 
>         Rmmod or unbind: I/O operations will succeed.
> 
> The second case is probably okay.  The first we can do nothing about.  
> However, in either case we do need to make sure that memory allocations
> do not require any writebacks.  This suggests that we need to call
> memalloc_noio_save() from within usb_unbind_interface().

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?

	Regards
		Oliver


  reply	other threads:[~2019-05-22  6:31 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-05-17 16:02 Jaewon Kim
2019-05-17 16:34 ` Matthew Wilcox
2019-05-18  1:53   ` Jaewon Kim
2019-05-20  5:56 ` Christoph Hellwig
2019-05-20  9:09   ` Oliver Neukum
2019-05-20 10:12     ` Christoph Hellwig
2019-05-20 14:16       ` Alan Stern
2019-05-20 14:23         ` Christoph Hellwig
2019-05-21  8:54           ` Oliver Neukum
2019-05-21 13:27             ` Christoph Hellwig
2019-05-21 13:11         ` Oliver Neukum
2019-05-21 14:00           ` Alan Stern
2019-05-22  6:31             ` Oliver Neukum [this message]
2019-05-22 14:56               ` Alan Stern
2019-05-22 20:47                 ` Oliver Neukum
2019-05-23 14:01                   ` Alan Stern
2019-05-28 12:34                     ` Oliver Neukum
2019-05-28 14:25                       ` Alan Stern
2019-05-23 12:32   ` Oliver Neukum
2019-05-23 16:35     ` Christoph Hellwig

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