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

["David Hildenbrand (Arm)" <david@kernel.org>]

On 6/3/26 18:19, Borislav Petkov wrote:
> On Wed, Jun 03, 2026 at 12:17:07PM -0400, Steven Rostedt wrote:
>> On Wed, 3 Jun 2026 15:44:54 +0200
>> "David Hildenbrand (Arm)" <david@kernel.org> wrote:
>>
>>> Likely the latter. BPF [1] documents:
>>>
>>> Q: Are tracepoints part of the stable ABI?
>>> A: NO. Tracepoints are tied to internal implementation details hence they are
>>> subject to change and can break with newer kernels. BPF programs need to change
>>> accordingly when this happens.
>>>
>>> The Kernel ABI document explicitly doesn't list them AFAIKS.
>>>
>>> There were previous discussions on the stability of tracepints [2], I don't know
>>> what changed in the meantime. CCing Steve
>>>
>>> [1] https://www.kernel.org/doc/html/latest/bpf/bpf_design_QA.html
>>> [2] https://lwn.net/Articles/747256/
>>> [3] https://www.kernel.org/doc/html/latest/admin-guide/abi.html
>>
>> Tracepoints are not stable or BPF programs only. But other applications
>> they are[1].
>>
>> Adding Linus as he's the Supreme Judge on the matter.
> 
> I *think* tools or libtraceevent can't really anticipate the TP namespace
> change so we might have to revert, I'm afraid...

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."

Which means that I now also fully understand

	"Some kernel maintainers prohibit or severely restrict the addition of
	 tracepoints to their subsystems out of fear that a similar thing could
	 happen to them. "

Whatever the result of this discussion will be, I'll try to document it.

-- 
Cheers,

David