Since the commit 91840be8f710 ("irq_work: Fix use-after-free in irq_work_single() on PREEMPT_RT"), we observed the performance of execve() is significantly impacted on MIPS. While we are unsure how that commit caused the impact or how to improve it (or even if it can be improved at all), implementing IRQ work with self-IPI seems able to mitigate the impaction. Perhaps this can/should be implemented for other MIPS architecture processors as well, but we don't have the enough knowledge of them, nor access to the hardware. So only implement it for loongson64 here. Link: https://lore.kernel.org/6be1cdd5f91dd7418a32ff372a6f3ae259b19195.camel@xry111.site/ Signed-off-by: Xi Ruoyao <xry111@xry111.site> Reviewed-by: Huacai Chen <chenhuacai@loongson.cn> Reviewed-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>