Re: Subject: io_uring/eventfd: registered eventfd signals only once after the cd305ee3633a backport (6.18.y, 6.12.y, Ubuntu 26.04)

[Greg KH <gregkh@linuxfoundation.org>]

On Fri, Nov 13, 2026 at 11:22:38PM +0000, dev@rebasedinc.com wrote:
> While working on my own async runtime on io_uring, I found what looks like a defect in the stable backports. I first saw it on Ubuntu 26.04's kernel, and I can't find any existing report of it.
> 
> A registered io_uring eventfd stops signaling after its first deferred signal on kernels that carry the backport of cd305ee3633a ("io_uring: defer eventfd signaling when queued from a wakeup handler") but not 04fe9aeb4f3c ("io_uring/eventfd: reset deferred signal state").
> 
> What I see, on Ubuntu 26.04 7.0.0-1016-aws, x86_64 and arm64. Ubuntu's 7.0 kernel took the cd305ee3633a backport through the 6.18.49 stable update:

Please test the real kernel.org 6.18.y release.  6.18.49 is very old.

If that still has a problem, please let us know and ideally send us a
backported patch.

thanks,

greg k-h