The patch below does not apply to the 6.12-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.
Thanks, Sasha ------------------ original commit in Linus's tree ------------------ >From 53b2fae90ff01fede6520ca744ed5e8e366497ba Mon Sep 17 00:00:00 2001 From: Shengming Hu <[email protected]> Date: Fri, 13 Feb 2026 14:29:32 +0800 Subject: [PATCH] function_graph: Restore direct mode when callbacks drop to one When registering a second fgraph callback, direct path is disabled and array loop is used instead. When ftrace_graph_active falls back to one, we try to re-enable direct mode via ftrace_graph_enable_direct(true, ...). But ftrace_graph_enable_direct() incorrectly disables the static key rather than enabling it. This leaves fgraph_do_direct permanently off after first multi-callback transition, so direct fast mode is never restored. Cc: [email protected] Link: https://patch.msgid.link/[email protected] Fixes: cc60ee813b503 ("function_graph: Use static_call and branch to optimize entry function") Signed-off-by: Shengming Hu <[email protected]> Signed-off-by: Steven Rostedt (Google) <[email protected]> --- kernel/trace/fgraph.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/trace/fgraph.c b/kernel/trace/fgraph.c index cc48d16be43e0..4df766c690f92 100644 --- a/kernel/trace/fgraph.c +++ b/kernel/trace/fgraph.c @@ -1303,7 +1303,7 @@ static void ftrace_graph_enable_direct(bool enable_branch, struct fgraph_ops *go static_call_update(fgraph_func, func); static_call_update(fgraph_retfunc, retfunc); if (enable_branch) - static_branch_disable(&fgraph_do_direct); + static_branch_enable(&fgraph_do_direct); } static void ftrace_graph_disable_direct(bool disable_branch) -- 2.51.0
