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From: Peter Zijlstra <peterz@infradead.org>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org,
	bpf@vger.kernel.org, x86@kernel.org,
	Masami Hiramatsu <mhiramat@kernel.org>,
	Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
	Josh Poimboeuf <jpoimboe@kernel.org>,
	Ingo Molnar <mingo@kernel.org>, Jiri Olsa <jolsa@kernel.org>,
	Namhyung Kim <namhyung@kernel.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Andrii Nakryiko <andrii@kernel.org>,
	Indu Bhagat <indu.bhagat@oracle.com>,
	"Jose E. Marchesi" <jemarch@gnu.org>,
	Beau Belgrave <beaub@linux.microsoft.com>,
	Jens Remus <jremus@linux.ibm.com>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [PATCH v10 04/14] unwind_user/deferred: Add unwind_deferred_trace()
Date: Thu, 19 Jun 2025 09:54:17 +0200	[thread overview]
Message-ID: <20250619075417.GW1613376@noisy.programming.kicks-ass.net> (raw)
In-Reply-To: <20250618112939.76f4bb87@gandalf.local.home>

On Wed, Jun 18, 2025 at 11:29:39AM -0400, Steven Rostedt wrote:

> Note, a request from the gcc folks is to add a system call that gives the
> user space application a backtrace from its current location. This can be
> handy for debugging as it would be similar to how we use dump_stack().

That makes very little sense to me; apps can typically unwind themselves
just fine, no? In fact, they can use DWARFs and all that.

Also, how about we don't make thing complicated and not confuse comments
with things like this? Focus on the deferred stuff (that's what these
patches are about) -- and then return-to-user is the one and only place
that makes sense.

  reply	other threads:[~2025-06-19  7:54 UTC|newest]

Thread overview: 79+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-06-11  0:54 [PATCH v10 00/14] unwind_user: x86: Deferred unwinding infrastructure Steven Rostedt
2025-06-11  0:54 ` [PATCH v10 01/14] unwind_user: Add user space unwinding API Steven Rostedt
2025-06-18 13:49   ` Peter Zijlstra
2025-06-11  0:54 ` [PATCH v10 02/14] unwind_user: Add frame pointer support Steven Rostedt
2025-06-18 13:52   ` Peter Zijlstra
2025-06-18 15:09     ` Steven Rostedt
2025-06-23 16:31       ` Indu Bhagat
2025-06-24 20:30         ` Steven Rostedt
2025-06-11  0:54 ` [PATCH v10 03/14] unwind_user: Add compat mode " Steven Rostedt
2025-06-18 13:46   ` Peter Zijlstra
2025-06-18 15:10     ` Steven Rostedt
2025-06-18 17:52       ` Linus Torvalds
2025-06-18 18:37         ` Steven Rostedt
2025-06-18 13:47   ` Peter Zijlstra
2025-06-18 15:18     ` Steven Rostedt
2025-06-19  7:51       ` Peter Zijlstra
2025-06-19  8:39         ` Steven Rostedt
2025-06-11  0:54 ` [PATCH v10 04/14] unwind_user/deferred: Add unwind_deferred_trace() Steven Rostedt
2025-06-18 13:54   ` Peter Zijlstra
2025-06-18 13:59   ` Peter Zijlstra
2025-06-18 15:20     ` Steven Rostedt
2025-06-18 16:26       ` Steven Rostedt
2025-06-18 14:01   ` Peter Zijlstra
2025-06-18 15:23     ` Steven Rostedt
2025-06-18 14:02   ` Peter Zijlstra
2025-06-18 15:29     ` Steven Rostedt
2025-06-19  7:54       ` Peter Zijlstra [this message]
2025-06-19  8:44         ` Steven Rostedt
2025-06-11  0:54 ` [PATCH v10 05/14] unwind_user/deferred: Add unwind cache Steven Rostedt
2025-06-18 14:13   ` Peter Zijlstra
2025-06-18 15:33     ` Steven Rostedt
2025-06-19  7:56       ` Peter Zijlstra
2025-06-19  8:47         ` Steven Rostedt
2025-06-19  9:04           ` Peter Zijlstra
2025-06-19  9:12             ` Steven Rostedt
2025-06-11  0:54 ` [PATCH v10 06/14] unwind_user/deferred: Add deferred unwinding interface Steven Rostedt
2025-06-18 14:20   ` Peter Zijlstra
2025-06-18 15:37     ` Steven Rostedt
2025-06-18 15:38       ` Steven Rostedt
2025-06-19  8:01       ` Peter Zijlstra
2025-06-19  8:49         ` Steven Rostedt
2025-06-18 18:46   ` Peter Zijlstra
2025-06-18 19:09     ` Steven Rostedt
2025-06-18 19:36       ` Steven Rostedt
2025-06-19  7:50       ` Peter Zijlstra
2025-06-19  8:56         ` Steven Rostedt
2025-06-19  9:11           ` Peter Zijlstra
2025-06-24 14:03             ` Steven Rostedt
2025-06-24 22:36     ` Steven Rostedt
2025-06-11  0:54 ` [PATCH v10 07/14] unwind_user/deferred: Make unwind deferral requests NMI-safe Steven Rostedt
2025-06-19  8:34   ` Peter Zijlstra
2025-06-19  8:37     ` Steven Rostedt
2025-06-19  8:44       ` Peter Zijlstra
2025-06-19  8:48         ` Peter Zijlstra
2025-06-19  9:10           ` Steven Rostedt
2025-06-19  9:24             ` Peter Zijlstra
2025-06-19  8:57   ` Peter Zijlstra
2025-06-19  9:07     ` Steven Rostedt
2025-06-19  9:32       ` Peter Zijlstra
2025-06-19  9:34         ` Peter Zijlstra
2025-06-19  9:42         ` Steven Rostedt
2025-06-19  9:45           ` Peter Zijlstra
2025-06-19 10:19             ` Steven Rostedt
2025-06-19 10:39               ` Peter Zijlstra
2025-06-19 13:04                 ` Steven Rostedt
2025-06-11  0:54 ` [PATCH v10 08/14] unwind deferred: Use bitmask to determine which callbacks to call Steven Rostedt
2025-06-20  8:15   ` Peter Zijlstra
2025-06-24 14:55     ` Steven Rostedt
2025-06-24 15:00       ` Peter Zijlstra
2025-06-24 16:36         ` Steven Rostedt
2025-06-11  0:54 ` [PATCH v10 09/14] unwind deferred: Use SRCU unwind_deferred_task_work() Steven Rostedt
2025-06-11  0:54 ` [PATCH v10 10/14] unwind: Clear unwind_mask on exit back to user space Steven Rostedt
2025-06-11  0:54 ` [PATCH v10 11/14] unwind: Finish up unwind when a task exits Steven Rostedt
2025-06-11  0:54 ` [PATCH v10 12/14] unwind_user/x86: Enable frame pointer unwinding on x86 Steven Rostedt
2025-06-11  0:54 ` [PATCH v10 13/14] perf/x86: Rename and move get_segment_base() and make it global Steven Rostedt
2025-06-11  0:54 ` [PATCH v10 14/14] unwind_user/x86: Enable compat mode frame pointer unwinding on x86 Steven Rostedt
2025-06-12 21:44 ` [PATCH v10 00/14] unwind_user: x86: Deferred unwinding infrastructure Andrii Nakryiko
2025-06-12 22:02   ` Josh Poimboeuf
2025-06-12 23:30     ` Andrii Nakryiko

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