From: Steven Rostedt <rostedt@goodmis.org>
To: Josh Poimboeuf <jpoimboe@kernel.org>
Cc: linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org,
Masami Hiramatsu <mhiramat@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
Andrew Morton <akpm@linux-foundation.org>,
x86@kernel.org, Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@kernel.org>,
Arnaldo Carvalho de Melo <acme@kernel.org>,
Indu Bhagat <indu.bhagat@oracle.com>,
Alexander Shishkin <alexander.shishkin@linux.intel.com>,
Jiri Olsa <jolsa@kernel.org>, Namhyung Kim <namhyung@kernel.org>,
Ian Rogers <irogers@google.com>,
Adrian Hunter <adrian.hunter@intel.com>,
linux-perf-users@vger.kernel.org, Mark Brown <broonie@kernel.org>,
linux-toolchains@vger.kernel.org, Jordan Rome <jordalgo@meta.com>,
Sam James <sam@gentoo.org>,
Andrii Nakryiko <andrii.nakryiko@gmail.com>,
Jens Remus <jremus@linux.ibm.com>,
Florian Weimer <fweimer@redhat.com>,
Andy Lutomirski <luto@kernel.org>, Weinan Liu <wnliu@google.com>,
Blake Jones <blakejones@google.com>,
Beau Belgrave <beaub@linux.microsoft.com>,
"Jose E. Marchesi" <jemarch@gnu.org>,
Alexander Aring <aahringo@redhat.com>
Subject: Re: [PATCH v6 11/18] perf: Use current->flags & PF_KTHREAD instead of current->mm == NULL
Date: Fri, 25 Apr 2025 13:34:16 -0400 [thread overview]
Message-ID: <20250425133416.63d3e3b8@gandalf.local.home> (raw)
In-Reply-To: <2fjdalrdgadbt6kmv7wgbc2vs42ojkwh2vj6yfwlttmoo2rijs@5gtrvow66g7m>
On Fri, 25 Apr 2025 08:09:55 -0700
Josh Poimboeuf <jpoimboe@kernel.org> wrote:
> On Fri, Apr 25, 2025 at 10:54:33AM -0400, Steven Rostedt wrote:
> > From: Steven Rostedt <rostedt@goodmis.org>
> >
> > To determine if a task is a kernel thread or not, it is more reliable to
> > use (current->flags & PF_KTHREAD) than to rely on current->mm being NULL.
> > That is because some kernel tasks (io_uring helpers) may have a mm field.
>
> There's a current->mm check in the user space unwinder (patch 1) which
> should probably also be converted.
Bah! OK.
I also plan on creating a couple of macros and running a coccinelle script
to replace all instances in the kernel of:
!(task->flags & PF_KTHREAD) into is_user_thread(task)
and
(task->flags & PF_KTHREAD) into is_kernel_thread(task)
As I've already screwed up missing the '!' (or adding it) a couple of
times. But caught it before posting the patches.
-- Steve
next prev parent reply other threads:[~2025-04-25 17:32 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-04-25 14:54 [PATCH v6 00/18] perf: Deferred unwinding of user space stack traces Steven Rostedt
2025-04-25 14:54 ` [PATCH v6 01/18] unwind_user: Add user space unwinding API Steven Rostedt
2025-04-25 14:54 ` [PATCH v6 02/18] unwind_user: Add frame pointer support Steven Rostedt
2025-04-25 14:54 ` [PATCH v6 03/18] unwind_user/x86: Enable frame pointer unwinding on x86 Steven Rostedt
2025-04-25 14:54 ` [PATCH v6 04/18] perf/x86: Rename and move get_segment_base() and make it global Steven Rostedt
2025-04-25 14:54 ` [PATCH v6 05/18] unwind_user: Add compat mode frame pointer support Steven Rostedt
2025-04-25 14:54 ` [PATCH v6 06/18] unwind_user/x86: Enable compat mode frame pointer unwinding on x86 Steven Rostedt
2025-04-25 14:54 ` [PATCH v6 07/18] unwind_user/deferred: Add unwind_deferred_trace() Steven Rostedt
2025-04-25 14:54 ` [PATCH v6 08/18] unwind_user/deferred: Add unwind cache Steven Rostedt
2025-04-25 14:54 ` [PATCH v6 09/18] perf: Remove get_perf_callchain() init_nr argument Steven Rostedt
2025-04-25 14:54 ` [PATCH v6 10/18] perf: Have get_perf_callchain() return NULL if crosstask and user are set Steven Rostedt
2025-04-25 14:54 ` [PATCH v6 11/18] perf: Use current->flags & PF_KTHREAD instead of current->mm == NULL Steven Rostedt
2025-04-25 15:09 ` Josh Poimboeuf
2025-04-25 17:34 ` Steven Rostedt [this message]
2025-04-25 14:54 ` [PATCH v6 12/18] perf: Simplify get_perf_callchain() user logic Steven Rostedt
2025-04-25 14:54 ` [PATCH v6 13/18] perf: Skip user unwind if the task is a kernel thread Steven Rostedt
2025-04-25 14:54 ` [PATCH v6 14/18] perf: Support deferred user callchains Steven Rostedt
2025-04-25 14:54 ` [PATCH v6 15/18] perf tools: Minimal CALLCHAIN_DEFERRED support Steven Rostedt
2025-04-25 14:54 ` [PATCH v6 16/18] perf record: Enable defer_callchain for user callchains Steven Rostedt
2025-04-25 14:54 ` [PATCH v6 17/18] perf script: Display PERF_RECORD_CALLCHAIN_DEFERRED Steven Rostedt
2025-04-25 14:54 ` [PATCH v6 18/18] perf tools: Merge deferred user callchains Steven Rostedt
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