linux-kernel - Re: [RFC] usb: host: u132-hcd: Remove deprecated create_singlethread

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Message-ID: <20160727192308.GP4144@mtj.duckdns.org>
Date:	Wed, 27 Jul 2016 15:23:08 -0400
From:	Tejun Heo <tj@...nel.org>
To:	Alan Stern <stern@...land.harvard.edu>
Cc:	Oliver Neukum <oneukum@...e.com>,
	Bhaktipriya Shridhar <bhaktipriya96@...il.com>,
	Geliang Tang <geliangtang@....com>,
	"GeyslanG.Bem@...yakshetra" <geyslan@...il.com>,
	Masanari Iida <standby24x7@...il.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Michal Hocko <MHocko@...e.com>,
	Vlastimil Babka <vbabka@...e.cz>,
	Mel Gorman <mgorman@...hsingularity.net>,
	Saurabh Karajgaonkar <skarajga@...teon.com>,
	linux-kernel@...r.kernel.org, linux-usb@...r.kernel.org
Subject: Re: [RFC] usb: host: u132-hcd: Remove deprecated
 create_singlethread_workqueue

Hello, Alan.

On Wed, Jul 27, 2016 at 02:54:51PM -0400, Alan Stern wrote:
> > Hmm... I didn't know the whole USB stack could operate without
> > allocating memory.  Does usb stack have mempools and stuff all the way
> > through?
> 
> No -- the USB stack does need to allocate memory in order to operate.  
> But it is careful to use GFP_NOIO or GFP_ATOMIC for allocations that
> might be on the block-device path.

Hmm... That doesn't really make them dependable during memory reclaim.
What happens when those allocations fail?

Thanks.

-- 
tejun