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

[ Upstream commit 16ed389227651330879e17bd83d43bd234006722 ]

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
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/kernel/events/core.c b/kernel/events/core.c
index 0339f60e349814dcd7a6a2e31506b7d03bf388f8..d6a86d8e9e59b74574dd1ccc47eefe8bfdff9deb 100644 (file)
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -7847,7 +7847,8 @@ 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;