From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 539653E92BB; Wed, 3 Jun 2026 16:26:29 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780503990; cv=none; b=gHcWTTAAnRR/58O8PAednAe59sXxvlF8JfKy3k5OCXL5RaTSar3Fzpb+C1w0ICeVWdKn0jlAXHYuSpVuDDA8FgQ9wA02AI/hWv8T9nsYSLREw4GFfjy7OE+TDJ8CrZ58X+SNyrQ1LUhhsvo+rFe6cTg2yV2aX4ZY1BVycGIKdRo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780503990; c=relaxed/simple; bh=IIPbXzoHVizbF6Vq7kqpg/jgp3F6synUIhzF2bX/vpY=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=LlaP7eazbwcjc5wM+IonXX5EkLd4IF2rb+FPGEghcrSrO63/eQEOS7ChkRJFe1RN6herfxU8tEgEvy5g3NeJpD6PxlZXW7aroR3dkzgagC0n4uhPZowQUWpb4YY/YglUC6tb1bd40nuJOuAoMi9c2UT/ASsDSoRnhHpt8TBzxFE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=NhoIe9Js; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="NhoIe9Js" Received: by smtp.kernel.org (Postfix) with ESMTPSA id F21021F00899; Wed, 3 Jun 2026 16:26:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1780503988; bh=AMe37VsnL6OyRGxikp8itIp9uDFnNxZm4xOo3bfJSBk=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=NhoIe9JseUy9QraWDOJQdPhHINeqv4tohxGqNkK9LGG7E8vjBqRyJOYMewcAm+3uf qMMNE2bV0v/L4yxpLT7jjmgoZbJkpSYDshkwIANRrH0Lwb9noLMMdT8XtQaOwYwhDq +Ka4d+KKNputJPuwp49kg2YjVX4M0tMn/ycMU6IvHh8S5UZKrieQ/7hFmsL/xrel01 K7LXaIeZM4XxVvMA8Cox8zSOfFfMPv0EPU72us7Epdn9odE4TGaCF/cXZk0amistvk fi6e/gCmEeLY2iDABj9ItLmQj91eaKLlN/0qnedqdf8ZlS2wLJmxPgBLb4+wcovGIc d5mH5+Od1N8Ww== Message-ID: <0c16bf3d-7c6d-4e28-b200-03b7d0ef714a@kernel.org> Date: Wed, 3 Jun 2026 18:26:24 +0200 Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: mm/memory-failure tracepoint change breaks userspace rasdaemon To: Borislav Petkov , Steven Rostedt Cc: "Zhuo, Qiuxu" , "mchehab+huawei@kernel.org" , "Luck, Tony" , "akpm@linux-foundation.org" , "linmiaohe@huawei.com" , "xieyuanbin1@huawei.com" , "Lai, Yi1" , "linux-kernel@vger.kernel.org" , "linux-edac@vger.kernel.org" , "linux-mm@kvack.org" , "linux-trace-kernel@vger.kernel.org" , Linus Torvalds References: <20260603121707.7eccb9fb@gandalf.local.home> <20260603161947.GBaiBUI7C8WWPwD84S@fat_crate.local> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit 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)" 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