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);
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