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
next prev parent 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 [RFC PATCH] usb: host: xhci: allow __GFP_FS in dma allocation 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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