From: Steven Rostedt <rostedt@kernel.org>
To: linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org,
linux-perf-users@vger.kernel.org
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
Josh Poimboeuf <jpoimboe@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@kernel.org>,
Namhyung Kim <namhyung@kernel.org>,
Alexei Starovoitov <alexei.starovoitov@gmail.com>,
Jens Axboe <axboe@kernel.dk>,
Masami Hiramatsu <mhiramat@kernel.org>,
Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
Andrew Morton <akpm@linux-foundation.org>
Subject: [PATCH 5/5] perf: Skip user unwind if the task is a kernel thread
Date: Thu, 17 Jul 2025 13:31:30 -0400 [thread overview]
Message-ID: <20250717173333.809101137@kernel.org> (raw)
In-Reply-To: 20250717173125.434618999@kernel.org
From: Josh Poimboeuf <jpoimboe@kernel.org>
If the task is not a user thread, there's no user stack to unwind.
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
---
kernel/events/core.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 1fa554e2666d..bd0a33f389d2 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -8166,7 +8166,8 @@ struct perf_callchain_entry *
perf_callchain(struct perf_event *event, struct pt_regs *regs)
{
bool kernel = !event->attr.exclude_callchain_kernel;
- bool user = !event->attr.exclude_callchain_user;
+ bool user = !event->attr.exclude_callchain_user &&
+ !(current->flags & (PF_KTHREAD | PF_USER_WORKER));
/* Disallow cross-task user callchains. */
bool crosstask = event->ctx->task && event->ctx->task != current;
const u32 max_stack = event->attr.sample_max_stack;
--
2.47.2
prev parent reply other threads:[~2025-07-17 17:33 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-07-17 17:31 [PATCH 0/5] perf: Clean ups and simplifications Steven Rostedt
2025-07-17 17:31 ` [PATCH 1/5] perf: Remove get_perf_callchain() init_nr argument Steven Rostedt
2025-07-17 17:31 ` [PATCH 2/5] perf: Have get_perf_callchain() return NULL if crosstask and user are set Steven Rostedt
2025-07-17 17:31 ` [PATCH 3/5] perf: Use current->flags & PF_KTHREAD|PF_USER_WORKER instead of current->mm == NULL Steven Rostedt
2025-07-17 17:31 ` [PATCH 4/5] perf: Simplify get_perf_callchain() user logic Steven Rostedt
2025-07-17 17:31 ` Steven Rostedt [this message]
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