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: <D7C36F69-23D6-4AD5-AED1-028119EAEE3F@gmail.com>
Date: Thu, 28 Aug 2025 15:58:31 -0300
From: Arnaldo Carvalho de Melo <arnaldo.melo@...il.com>
To: Linus Torvalds <torvalds@...ux-foundation.org>,
 Steven Rostedt <rostedt@...nel.org>
CC: 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 August 28, 2025 3:39:35 PM GMT-03:00, Linus Torvalds <torvalds@...ux-foundation.org> wrote:
>On Thu, 28 Aug 2025 at 11:05, Steven Rostedt <rostedt@...nel.org> wrote:
>>
>> The deferred user space stacktrace event already does a lookup of the vma
>> for each address in the trace to get the file offset for those addresses,
>> it can also report the file itself.
>
>That sounds like a good idea..
>
>But the implementation absolutely sucks:
>
>> Add two more arrays to the user space stacktrace event. One for the inode
>> number, and the other to store the device major:minor number. Now the
>> output looks like this:
>
>WTF? Why are you back in the 1960's? What's next? The index into the
>paper card deck?
>
>Stop using inode numbers and device numbers already. It's the 21st
>century. No, cars still don't fly, but dammit, inode numbers were a
>great idea back in the days, but they are not acceptable any more.
>
>They *particularly* aren't acceptable when you apparently think that
>they are 'unsigned long'.  Yes, that's the internal representation we
>use for inode indexing, but for example on nfs the inode is actually
>bigger. It's exposed to user space as a u64 through
>
>        stat->ino = nfs_compat_user_ino64(NFS_FILEID(inode));
>
>so the inode that user space sees in 'struct stat' (a) doesn't
>actually match inode->i_ino, and (b) isn't even the full file ID that
>NFS actually uses.
>
>Let's not let that 60's thinking be any part of a new interface.
>
>Give the damn thing an actual filename or something *useful*, not a
>number that user space can't even necessarily match up to anything.
>

A build ID?

PERF_RECORD_MMAP went thru this, filename ->  inode -> Content based hash

- Arnaldo