FAILED: patch "[PATCH] fgraph: Fix thresh_return clear per-task notrace" failed to apply to 6.18-stable tree

The patch below does not apply to the 6.18-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]>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.18.y
git checkout FETCH_HEAD
git cherry-pick -x 6ca8379b5d36e22b04e6315c3e49a6083377c862
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2026031701-backer-clumsy-6f09@gregkh' --subject-prefix 'PATCH 6.18.y' HEAD^..

Possible dependencies:

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 6ca8379b5d36e22b04e6315c3e49a6083377c862 Mon Sep 17 00:00:00 2001
From: Shengming Hu <[email protected]>
Date: Sat, 21 Feb 2026 11:30:07 +0800
Subject: [PATCH] fgraph: Fix thresh_return clear per-task notrace

When tracing_thresh is enabled, function graph tracing uses trace_graph_thresh_return() as the return handler. Unlike trace_graph_return(), it did not clear the per-task TRACE_GRAPH_NOTRACE flag set by the entry handler for set_graph_notrace addresses. This could leave the task permanently in "notrace" state and effectively disable function graph tracing for that task.

Mirror trace_graph_return()'s per-task notrace handling by clearing TRACE_GRAPH_NOTRACE and returning early when set.

index 3d8239fee004..817d0f1696b6 100644
@@ -400,14 +400,15 @@ static void trace_graph_thresh_return(struct ftrace_graph_ret *trace,
 				      struct fgraph_ops *gops,
 				      struct ftrace_regs *fregs)
 {
+	unsigned long *task_var = fgraph_get_task_var(gops);
 	struct fgraph_times *ftimes;
 	struct trace_array *tr;
 	int size;
 
 	ftrace_graph_addr_finish(gops, trace);
 
-	if (trace_recursion_test(TRACE_GRAPH_NOTRACE_BIT)) {
-		trace_recursion_clear(TRACE_GRAPH_NOTRACE_BIT);
+	if (*task_var & TRACE_GRAPH_NOTRACE) {
+		*task_var &= ~TRACE_GRAPH_NOTRACE;
 		return;
 	}
 

From: Shengming Hu <[email protected]>

[ Upstream commit 6ca8379b5d36e22b04e6315c3e49a6083377c862 ]

When tracing_thresh is enabled, function graph tracing uses trace_graph_thresh_return() as the return handler. Unlike trace_graph_return(), it did not clear the per-task TRACE_GRAPH_NOTRACE flag set by the entry handler for set_graph_notrace addresses. This could leave the task permanently in "notrace" state and effectively disable function graph tracing for that task.

Mirror trace_graph_return()'s per-task notrace handling by clearing TRACE_GRAPH_NOTRACE and returning early when set.

---
 kernel/trace/trace_functions_graph.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

index a7f4b9a47a71a..b53d83b619401 100644
@@ -378,13 +378,14 @@ static void trace_graph_thresh_return(struct ftrace_graph_ret *trace,
 				      struct fgraph_ops *gops,
 				      struct ftrace_regs *fregs)
 {
+	unsigned long *task_var = fgraph_get_task_var(gops);
 	struct fgraph_times *ftimes;
 	int size;
 
 	ftrace_graph_addr_finish(gops, trace);
 
-	if (trace_recursion_test(TRACE_GRAPH_NOTRACE_BIT)) {
-		trace_recursion_clear(TRACE_GRAPH_NOTRACE_BIT);
+	if (*task_var & TRACE_GRAPH_NOTRACE) {
+		*task_var &= ~TRACE_GRAPH_NOTRACE;
 		return;
 	}
 

2.51.0