Re: psi_trigger_poll() is completely broken

[Suren Baghdasaryan]

On Mon, Jan 10, 2022 at 9:42 AM Linus Torvalds
<torvalds@xxxxxxxxxxxxxxxxxxxx> wrote:
>
> On Mon, Jan 10, 2022 at 9:25 AM Suren Baghdasaryan <surenb@xxxxxxxxxx> wrote:
> >
> > About the issue of serializing concurrent writes for
> > cgroup_pressure_write() similar to how psi_write() does. Doesn't
> > of->mutex inside kernfs_fop_write_iter() serialize the writes to the
> > same file?
>
> Ahh, yes, it looks like that does solve the serialization issue.
> Sorry, I missed that because I'm not actually all that familiar with
> the kernfs 'of' code.
>
> So the only issue is the trigger lifetime one, and if a single trigger
> is sufficient and returning -EBUSY for trying to replace an existing
> one is good, then I think that's the proper fix.
>
> I'm very busy with the merge window (and some upcoming travel and
> family events), so I'm hoping somebody will write and test such a
> patch. Please?

Yes, definitely. I'm on it. Will try posting it later today or
tomorrow morning if testing reveals something unexpected.
Thanks!

>
>                    Linus