linux-kernel - Re: [PATCH v6 5/6] tracing: Show inode and device major:minor in deferred user space stacktrace

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CAHk-=wj-ZfHXfXKtSNKoRXhNz10Do+mqDyUumEkx8H8OqVYP-A@mail.gmail.com>
Date: Fri, 29 Aug 2025 10:02:40 -0700
From: Linus Torvalds <torvalds@...ux-foundation.org>
To: Steven Rostedt <rostedt@...dmis.org>
Cc: Steven Rostedt <rostedt@...nel.org>, Arnaldo Carvalho de Melo <arnaldo.melo@...il.com>, 
	linux-kernel@...r.kernel.org, linux-trace-kernel@...r.kernel.org, 
	bpf@...r.kernel.org, x86@...nel.org, Masami Hiramatsu <mhiramat@...nel.org>, 
	Mathieu Desnoyers <mathieu.desnoyers@...icios.com>, Josh Poimboeuf <jpoimboe@...nel.org>, 
	Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...nel.org>, Jiri Olsa <jolsa@...nel.org>, 
	Arnaldo Carvalho de Melo <acme@...nel.org>, Namhyung Kim <namhyung@...nel.org>, 
	Thomas Gleixner <tglx@...utronix.de>, Andrii Nakryiko <andrii@...nel.org>, 
	Indu Bhagat <indu.bhagat@...cle.com>, "Jose E. Marchesi" <jemarch@....org>, 
	Beau Belgrave <beaub@...ux.microsoft.com>, Jens Remus <jremus@...ux.ibm.com>, 
	Andrew Morton <akpm@...ux-foundation.org>, Florian Weimer <fweimer@...hat.com>, 
	Sam James <sam@...too.org>, Kees Cook <kees@...nel.org>, "Carlos O'Donell" <codonell@...hat.com>
Subject: Re: [PATCH v6 5/6] tracing: Show inode and device major:minor in
 deferred user space stacktrace

On Fri, 29 Aug 2025 at 09:57, Steven Rostedt <rostedt@...dmis.org> 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