linux-kernel - Re: 4.12.0-rc6+: WQ_MEM_RECLAIM hci0:hci_power_off is flushing !WQ_MEM_RECLAIM events:btusb

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Message-ID: <20170627152032.GA2289@htj.duckdns.org>
Date:   Tue, 27 Jun 2017 11:20:32 -0400
From:   Tejun Heo <tj@...nel.org>
To:     Dominik Brodowski <linux@...inikbrodowski.net>,
        Marcel Holtmann <marcel@...tmann.org>,
        Gustavo Padovan <gustavo@...ovan.org>,
        Johan Hedberg <johan.hedberg@...il.com>
Cc:     linux-kernel@...r.kernel.org, linux-bluetooth@...r.kernel.org
Subject: Re: 4.12.0-rc6+: WQ_MEM_RECLAIM hci0:hci_power_off is flushing
 !WQ_MEM_RECLAIM events:btusb_work

Hello,

On Sun, Jun 25, 2017 at 08:21:49PM +0200, Dominik Brodowski wrote:
> On my Dell XPS 13 9343 (x86_64), the following warning was logged right
> after a resume from suspend-to-mem (not on *every* resume, though, so it
> might be hard to reproduce). The kernel is v4.12.0-rc6+ as of 94a6df251dd0,
> and I don't really use bluetooth, though the drivers are loaded:
> 
> PM: Finishing wakeup.
> OOM killer enabled.
> Restarting tasks ... done.
> Bluetooth: hci0: read Intel version: 370710018002030d00
> Bluetooth: hci0: Intel Bluetooth firmware file: intel/ibt-hw-37.7.10-fw-1.80.2.3.d.bseq
> Bluetooth: hci0: Intel Bluetooth firmware patch completed and activated
> ... <more, unrelated messages>
> workqueue: WQ_MEM_RECLAIM hci0:hci_power_off is flushing !WQ_MEM_RECLAIM events:btusb_work

So, WQ_MEM_RECLAIM has to be transitive; otherwise, it doesn't mean
anything.  I have a hard time believing that bluetooth actually needs
WQ_MEM_RECLAIM unless people mount nfs through a bluetooth tethered
phone.  Would it be possible to remove WQ_MEM_RECLAIM from these
workqueues?

Thanks.

-- 
tejun