Re: mm/memory-failure tracepoint change breaks userspace rasdaemon

[Andrew Morton]

On Wed, 3 Jun 2026 13:00:06 -0400 Steven Rostedt <rostedt@xxxxxxxxxxx> wrote:

> On Wed, 3 Jun 2026 18:26:24 +0200
> "David Hildenbrand (Arm)" <david@xxxxxxxxxx> wrote:
> 
> > Yeah, I was fearing that when I read in [2]:
> > 
> > 	"It has become clear in the past that this promise extends to
> > 	 tracepoints, most notably in 2011 when a tracepoint change broke
> > 	 powertop and had to be reverted."
> 
> Technically the issue is with trace events and not tracepoints. The
> difference is that a trace event is created via the TRACE_EVENT() macro
> which defines what is to be collected from the tracepoint and exposes that
> information to tracefs which applications can easily see.
> 
> A tracepoint is simply the hook in the code that you can attach to. Trace
> events create a callback from that hook to extract the data from the
> tracepoint to fill in the fields.

The problem here appears to be that "ras:memory_failure_event" became
"memory_failure:memory_failure_event".

Perhaps we can add infrastructure to permit aliasing "ras" onto
"memory_failure".  So if we make these namespace alterations we can
easily preserve back-compatibility?