When process exits or execute new binary, it will call function
exit_mmap with old mm, there is such function call trace:
exit_mmap(struct mm_struct *mm)
--> tlb_finish_mmu(&tlb, 0, -1)
--> arch_tlb_finish_mmu(tlb, start, end, force)
--> tlb_flush_mmu(tlb);
--> tlb_flush(struct mmu_gather *tlb)
--> flush_tlb_mm(tlb->mm)
It is not necessary to flush tlb since oldmm is not used anymore
by the process, there is similar operations on IA64/ARM64 etc,
this patch adds such optimization on MIPS.
Signed-off-by: Mao Bibo <maobibo@xxxxxxxxxxx>
---
arch/mips/kernel/smp.c | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/arch/mips/kernel/smp.c b/arch/mips/kernel/smp.c
index 1986d1309410..1d93b85271ba 100644
--- a/arch/mips/kernel/smp.c
+++ b/arch/mips/kernel/smp.c
@@ -518,6 +518,12 @@ static inline void smp_on_each_tlb(void (*func) (void *info), void *info)
void flush_tlb_mm(struct mm_struct *mm)
{
+ if (!mm)
+ return;
+
+ if (atomic_read(&mm->mm_users) == 0)
+ return; /* happens as a result of exit_mmap() */
+
preempt_disable();
if (cpu_has_mmid) {
--
2.27.0
