Re: waitqueue lockdep annotation

[Andrew Morton]

On Thu, 30 Nov 2017 06:20:35 -0800 Christoph Hellwig <hch@xxxxxx> wrote:

> Hi all,
> 
> this series adds a strategic lockdep_assert_held to __wake_up_common
> to ensure callers really do hold the wait_queue_head lock when calling
> the unlocked wake_up variants.  It turns out epoll did not do this
> for a fairly common path (hit all the time by systemd during bootup),
> so the second patch fixed this instance as well.

What are the runtime effects of the epoll bug?