| Message ID | 20220510114441.2959886-1-maobibo@loongson.cn (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | 84595f450a8fc773a5543e2a0cca55067db38a8d |
| Headers | show |
| Series | MIPS: smp: optimization for flush_tlb_mm when exiting | expand |
On Tue, May 10, 2022 at 07:44:41PM +0800, Mao Bibo wrote: > 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@loongson.cn> > --- > arch/mips/kernel/smp.c | 6 ++++++ > 1 file changed, 6 insertions(+) applied to mips-next. Thomas.
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) {
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@loongson.cn> --- arch/mips/kernel/smp.c | 6 ++++++ 1 file changed, 6 insertions(+)