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

diff --git a/kernel/events/core.c b/kernel/events/core.c
index f880cec0c98095d7916afcb593bab31b8b440b0d..28de3baff792224a4efbf8c2e6868f6d7d24005e 100644 (file)
--- 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;