The following commit has been merged into the perf/core branch of tip:

Commit-ID:     16ed389227651330879e17bd83d43bd234006722
Gitweb:        https://git.kernel.org/tip/16ed389227651330879e17bd83d43bd234006722
Author:        Josh Poimboeuf <jpoimboe@kernel.org>
AuthorDate:    Wed, 20 Aug 2025 14:03:43 -04:00
Committer:     Peter Zijlstra <peterz@infradead.org>
CommitterDate: Tue, 26 Aug 2025 09:51:13 +02:00

perf: Skip user unwind if the task is a kernel thread

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>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20250820180428.930791978@kernel.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 f880cec..28de3ba 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -8198,7 +8198,8 @@ 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;