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 012CA3168EF; Wed, 3 Jun 2026 13:44:59 +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=1780494300; cv=none; b=t1j4/cDUhzNwKNZpPTXmoe9Y7U81T94ZuwXQ6+tv0hIQmbLtt82RqNhKUqd1OV/rRF+yR2I85iMR4E9Fu+Zvs/Xsnv3TuNM5uH4SrNFqdqsEcR4F4ugyoz15rnlUZ9a57qe9cDTl7AaEtOi3w+I20w6k0c6xv2+bR1Ju6Rl6eKg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780494300; c=relaxed/simple; bh=w76++h12UwTix1AQskx9/mzTq4FG3jWxNWFN1G8aIfA=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=S/mbhjluqPxbQLbz24JttViTLnCu+qIXGSM0soknGN8hrKcS+TyjG8qifsJTPD1I22lnu3QVnh1Yqz4ZE5NuROi9YvZqG3lLgT1iItoXFb3YSxG1TqSxuL7FNSuyL2gBxOvzSieYmZan21uE3ovVgyFJOmMos7aYA+37ayCNl1s= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=TmG7iI+A; 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="TmG7iI+A" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 944BF1F00893; Wed, 3 Jun 2026 13:44:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1780494299; bh=UAcEW5sdNzXOvmfS53awUiH9gNX5gi+01tp59tm5Mgo=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=TmG7iI+ADon1SUHGYPnaGVvdMlaCwNhAUdiLnKnBVhjmEuAiUJ3gucXtELvOYXjjY wfjdALcg3+UuQiIPuVgR7//OC8D1F0K2QstqgbbTNpJxgRDkbV6s8+ES+JLVDADvzX 0bed1eQkhDy84HStoEhqYmFnF4Tk08e7wxUUivCRSTqB59usF6Zo/uedWhmz4lq9yA ih+wOYHOZgPJYAHVBNW0glj9x9vplX2goojLzY1DrKAi9RsnOJ8zQzN0bDQrAyzvt2 7IVMk3i22Pep6O1zRHtTiyalbT97jJiopI2/0Hj/lphkZ4laxlKmrnaEvVzb68B9mn VlKNASpUU2+jA== Message-ID: Date: Wed, 3 Jun 2026 15:44:54 +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: "Zhuo, Qiuxu" , "rostedt@goodmis.org" , "mchehab+huawei@kernel.org" , "Luck, Tony" , "bp@alien8.de" , "akpm@linux-foundation.org" , "linmiaohe@huawei.com" , "xieyuanbin1@huawei.com" Cc: "Lai, Yi1" , "linux-kernel@vger.kernel.org" , "linux-edac@vger.kernel.org" , "linux-mm@kvack.org" , "linux-trace-kernel@vger.kernel.org" References: From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 8bit On 6/3/26 15:11, Zhuo, Qiuxu wrote: > Hi, > >   > > Laiyi reported that the userspace rasdaemon fails to enable memory_failure_event > on kernels >= v6.19. > >   > > Kernel commit 31807483d395 ("mm/memory-failure: remove the selection of RAS"), > merged in v6.19-rc1, > > moved the memory_failure_event tracepoint from the "ras" subsystem to > "memory_failure". > > However, rasdaemon still tries to enable: > >   > >     ras:memory_failure_event > >   > > while on v6.19+ kernels, the tracepoint is: > >   > >     memory_failure:memory_failure_event > >   > > As a result, rasdaemon fails to start: > >   > >     … > >    Can't write to set_event > >    Huh! something got wrong. Aborting. > >    … > >   > > Reproducer: > >   > >     rasdaemon --enable > >   > > Could you please let me know whether the preferred solution is to revert the > kernel change, > > or to update rasdaemon to support both tracepoint names for backward/forward > compatibility? 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 -- Cheers, David