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Received: from 77-249-17-252.cable.dynamic.v4.ziggo.nl ([77.249.17.252] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.99.1 #2 (Red Hat Linux)) id 1wqoBE-0000000BI5c-1vwb; Mon, 03 Aug 2026 08:37:52 +0000 Received: by noisy.programming.kicks-ass.net (Postfix, from userid 1000) id A2BE9301127; Mon, 03 Aug 2026 10:37:50 +0200 (CEST) Date: Mon, 3 Aug 2026 10:37:50 +0200 From: Peter Zijlstra To: Eugene Mavick Cc: Will Deacon , Boqun Feng , Mark Rutland , Gary Guo , Steven Rostedt , Masami Hiramatsu , Mathieu Desnoyers , Andrew Morton , Dennis Zhou , Tejun Heo , Christoph Lameter , linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH v4 0/5] tracing: add ref_trace_final_put tracing Message-ID: <20260803083750.GA49951@noisy.programming.kicks-ass.net> References: <20260801-refcount-final-put-trace-v4-0-2e58678f0ffd@mavick.dev> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260801-refcount-final-put-trace-v4-0-2e58678f0ffd@mavick.dev> X-Rspam-User: X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: 2EA41180005 X-Stat-Signature: xreqjmjoa8sps9rygoedgosok1ge6tk6 X-HE-Tag: 1785746300-810075 X-HE-Meta: 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 H0UI/NmY WRkVgFICFDigoCDlTuQwDNOaTC7ugYQI5jPOALx/87onWGqFd4jLMnK7Rjm28nSnYo2uD+iss1c5fYUBHW6b864h+Go9hDb6x5R/2OGWzHcHULfvDi2LQ1E30UXLLzXuhQkqbZ6rhyzaz4HEhWC1W9HoJpo8a/ENDQD/kvWs5WxMknjv5k0kijFQUdG5GbhDAheAfTNyzGdn6VaDNothYDAh45l/rEylQondVx66R4JFOf6GzYFgy8MxVnsu85rPtt2z6ukfjfqCVzKVDdP2S9M/tSA== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Sat, Aug 01, 2026 at 06:59:40PM +0800, Eugene Mavick wrote: > When debugging use-after-free(UAF) bugs, knowing when the object reaches > 0 references and enters final release can significantly aid the > debugging process. > > There is currently no universal way to trace this information. > > This patch series implements tracing of the final puts in the > most widely used refcounting implementations, > refcount_t(and thus kref which uses it), and percpu-ref. > > The tracepoint records three fields: > - caller: function that called the refcounting > function(refcount_sub_and_test, percpu_ref_put_many) > - ip: return address of the trace wrapper macro call > - obj: refcount object(struct percpu_ref, refcount_t) > > Signed-off-by: Eugene Mavick I'm not sure this Changelog is convincing me. To me this just looks like more weight / bloat without benefit.