Messages in this thread Patch in this message | | | From | Xiaochen Shen <> | Subject | [PATCH] x86/resctrl: Take care of PF_EXITING task in callback | Date | Thu, 9 Jan 2020 00:13:46 +0800 |
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When writing a pid to file "tasks", a callback function move_myself() is queued to this task to be called when the task returns from kernel mode or exits. The purpose of move_myself() is to activate the newly assigned closid and/or rmid associated with this task. This activation is done by calling resctrl_sched_in() from move_myself(), the same function that is called when switching to this task.
If this work is successfully queued but then the task enters PF_EXITING status (e.g., receiving signal SIGKILL, SIGTERM) prior to the execution of the callback move_myself() then move_myself() still calls resctrl_sched_in() since the task status is not currently considered.
When a task is exiting then the data structure of the task itself will be freed soon, calling resctrl_sched_in() to write the register that control's the task's resources is unnecessary and it implies extra performance overhead.
Add check on task status in move_myself() and return immediately if the task is PF_EXITING.
Signed-off-by: Xiaochen Shen <xiaochen.shen@intel.com> Reviewed-by: Reinette Chatre <reinette.chatre@intel.com> --- arch/x86/kernel/cpu/resctrl/rdtgroup.c | 4 ++++ 1 file changed, 4 insertions(+)
diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c index 2e3b06d6bbc6..205925d802d8 100644 --- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c +++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c @@ -532,11 +532,15 @@ static void move_myself(struct callback_head *head) kfree(rdtgrp); } + if (unlikely(current->flags & PF_EXITING)) + goto out; + preempt_disable(); /* update PQR_ASSOC MSR to make resource group go into effect */ resctrl_sched_in(); preempt_enable(); +out: kfree(callback); } -- 1.8.3.1
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