Re: [PATCH AUTOSEL 4.18 08/27] Input: evdev - add a schedule point in evdev_write()

From: Sasha Levin
Date: Tue Oct 23 2018 - 11:49:15 EST


On Mon, Oct 22, 2018 at 10:02:44AM -0700, Dmitry Torokhov wrote:
Hi Sasha,

On Mon, Oct 22, 2018 at 06:19:05AM -0400, Sasha Levin wrote:
From: Dmitry Torokhov <dmitry.torokhov@xxxxxxxxx>

[ Upstream commit 36d2582ff235b4e01ad64a734c877a52dc762d9c ]

Large writes to evdev interface may cause rcu stalls. Let's add
cond_resched() to the loop to avoid this.

This is not needed in stable:

- the interfaces are not accessible for unprivileged users so there is
no DOS concerns
- the issue can only happen on non-preemptible kernels
- the issue only showed up with synthetic test and not real life use
cases
- this is not a regression

The same goes to similar patches to mousedev, joydev and uinput that you
autoselected.

Dropped, thanks!

--
Thanks,
Sasha