Re: [PATCH RESEND] x86/split_lock: Warn for bus locks once for each task

[Maksim Davydov]

On 9/17/25 18:37, Pedro Falcato wrote:
> On Wed, Sep 17, 2025 at 05:41:11PM +0300, Maksim Davydov wrote:
> > Hi!
>
> Hi!
>
> > I've tested this patch (VM w/ bus lock detection and w/o split lock
> > detection). The warn mode works fine and as expected with only one
> > notification per task. However, the ratelimit mode has been changed too:
> > only one notification per task will be in dmesg, because this mode reuses
> > notification code of warn mode. But in the documentation for ratelimit mode
> > there is nothing about the limit of notifications: "Limit bus lock rate to N
> > bus locks per second system wide and warn on bus locks.". Thus, I think that
> > ratelimit mode should remain old behaviour.
>
> So, you're suggesting different "warn" behaviors depending on =warn vs
> =ratelimit? I don't have a particularly strong opinion here, but I was assuming
> that "warn on bus locks" means "do whatever =warn is supposed to do". I'm not
> sure warning every time gains you much, though.

For me, it's ok to reduce the number of messages to one per task.

By the way, I read the patch again and noticed that split_lock_warn() 
and handle_bus_lock() print messages in the same way. Maybe, it'll be 
better to implement an auxiliary wrapper for printing 
split_lock/bus_lock warning messages (for example, 
print_sl_warn_once()), what do you think?

--
Best regards,
Maksim Davydov