The following commit has been merged into the sched/core branch of tip:
Commit-ID: d428aac9dff0a0d217f3449884ac958dbf3f232b
Gitweb: https://git.kernel.org/tip/d428aac9dff0a0d217f3449884ac958dbf3f232b
Author: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
AuthorDate: Tue, 28 Sep 2021 14:24:28 +02:00
Committer: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
CommitterDate: Fri, 01 Oct 2021 13:58:07 +02:00
sched: Move kprobes cleanup out of finish_task_switch()
Doing cleanups in the tail of schedule() is a latency punishment for the
incoming task. The point of invoking kprobes_task_flush() for a dead task
is that the instances are returned and cannot leak when __schedule() is
kprobed.
Move it into the delayed cleanup.
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Link: https://lkml.kernel.org/r/20210928122411.537994026@xxxxxxxxxxxxx
---
kernel/exit.c | 2 ++
kernel/kprobes.c | 8 ++++----
kernel/sched/core.c | 6 ------
3 files changed, 6 insertions(+), 10 deletions(-)
diff --git a/kernel/exit.c b/kernel/exit.c
index fd1c041..df281b4 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -64,6 +64,7 @@
#include <linux/rcuwait.h>
#include <linux/compat.h>
#include <linux/io_uring.h>
+#include <linux/kprobes.h>
#include <linux/uaccess.h>
#include <asm/unistd.h>
@@ -169,6 +170,7 @@ static void delayed_put_task_struct(struct rcu_head *rhp)
{
struct task_struct *tsk = container_of(rhp, struct task_struct, rcu);
+ kprobe_flush_task(tsk);
perf_event_delayed_put(tsk);
trace_sched_process_free(tsk);
put_task_struct(tsk);
diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index 745f08f..89194e5 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -1256,10 +1256,10 @@ void kprobe_busy_end(void)
}
/*
- * This function is called from finish_task_switch when task tk becomes dead,
- * so that we can recycle any function-return probe instances associated
- * with this task. These left over instances represent probed functions
- * that have been called but will never return.
+ * This function is called from delayed_put_task_struct() when a task is
+ * dead and cleaned up to recycle any function-return probe instances
+ * associated with this task. These left over instances represent probed
+ * functions that have been called but will never return.
*/
void kprobe_flush_task(struct task_struct *tk)
{
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 8d844d0..8e49b17 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -4783,12 +4783,6 @@ static struct rq *finish_task_switch(struct task_struct *prev)
if (prev->sched_class->task_dead)
prev->sched_class->task_dead(prev);
- /*
- * Remove function-return probe instances associated with this
- * task and put them back on the free list.
- */
- kprobe_flush_task(prev);
-
/* Task is done with its stack. */
put_task_stack(prev);
|