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[209.85.218.43]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-aff03e9ba10sm186400866b.52.2025.08.29.10.09.59 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 29 Aug 2025 10:09:59 -0700 (PDT) Received: by mail-ej1-f43.google.com with SMTP id a640c23a62f3a-afcb6856dfbso422646566b.1 for ; Fri, 29 Aug 2025 10:09:59 -0700 (PDT) X-Forwarded-Encrypted: i=1; AJvYcCU5LzuwTTMAPRkvSmXDp+CSxBenK2A6TrTmgdaStxG2BDGV4BSOm7NiONW0SZ9DYFIAnRZomTb2/+BYKtY=@vger.kernel.org X-Received: by 2002:a17:907:6eab:b0:afe:ef8a:a48c with SMTP id a640c23a62f3a-afeef8ac7f9mr611238166b.8.1756486976814; Fri, 29 Aug 2025 10:02:56 -0700 (PDT) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 References: <20250828180300.591225320@kernel.org> <20250828180357.223298134@kernel.org> <20250828161718.77cb6e61@batman.local.home> <20250828164819.51e300ec@batman.local.home> <20250828171748.07681a63@batman.local.home> <20250829110639.1cfc5dcc@gandalf.local.home> <20250829123321.63c9f525@gandalf.local.home> <20250829125756.2be2a3c3@gandalf.local.home> In-Reply-To: <20250829125756.2be2a3c3@gandalf.local.home> From: Linus Torvalds Date: Fri, 29 Aug 2025 10:02:40 -0700 X-Gmail-Original-Message-ID: X-Gm-Features: Ac12FXypzub4sT_YQp3-NVQ4K7fOdzCL-9SS4ZE75x9Zoqx6YPOM5EIXszDBXRM Message-ID: Subject: Re: [PATCH v6 5/6] tracing: Show inode and device major:minor in deferred user space stacktrace To: Steven Rostedt Cc: Steven Rostedt , Arnaldo Carvalho de Melo , linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, bpf@vger.kernel.org, x86@kernel.org, Masami Hiramatsu , Mathieu Desnoyers , Josh Poimboeuf , Peter Zijlstra , Ingo Molnar , Jiri Olsa , Arnaldo Carvalho de Melo , Namhyung Kim , Thomas Gleixner , Andrii Nakryiko , Indu Bhagat , "Jose E. Marchesi" , Beau Belgrave , Jens Remus , Andrew Morton , Florian Weimer , Sam James , Kees Cook , "Carlos O'Donell" Content-Type: text/plain; charset="UTF-8" On Fri, 29 Aug 2025 at 09:57, Steven Rostedt wrote: > > The reason is to keep from triggering the event that records the pathname > for every look up. BUT THAT WAS NEVER THE POINT. There is only a single 64-bit number. No lookup. No pointer following. No nothing. The whole point of hashing was to get an *opaque* thing very quickly. Not a pathname. No reference counting. No verifying whether you have seen it before. Literally just something that you can match up in the trace file much much later. (And, honestly, the likely thing is that you never match it up at all - you can delay the "match it up" until a human actually looks at a trace, which is presumably going to be a "one in a million" case). Linus