On Sat, Nov 28, 2020 at 8:01 AM Nicholas Piggin <npiggin@xxxxxxxxx> wrote:
>
> This is called at points where a lazy mm is switched away or made not
> lazy (by its owner switching back).
>
> Signed-off-by: Nicholas Piggin <npiggin@xxxxxxxxx>
> ---
> arch/arm/mach-rpc/ecard.c | 1 +
> arch/powerpc/mm/book3s64/radix_tlb.c | 1 +
> fs/exec.c | 6 ++++--
> include/asm-generic/mmu_context.h | 21 +++++++++++++++++++++
> kernel/kthread.c | 1 +
> kernel/sched/core.c | 2 ++
> 6 files changed, 30 insertions(+), 2 deletions(-)
>
> diff --git a/arch/arm/mach-rpc/ecard.c b/arch/arm/mach-rpc/ecard.c
> index 827b50f1c73e..43eb1bfba466 100644
> --- a/arch/arm/mach-rpc/ecard.c
> +++ b/arch/arm/mach-rpc/ecard.c
> @@ -253,6 +253,7 @@ static int ecard_init_mm(void)
> current->mm = mm;
> current->active_mm = mm;
> activate_mm(active_mm, mm);
> + exit_lazy_tlb(active_mm, current);
> mmdrop(active_mm);
> ecard_init_pgtables(mm);
> return 0;
> diff --git a/arch/powerpc/mm/book3s64/radix_tlb.c b/arch/powerpc/mm/book3s64/radix_tlb.c
> index b487b489d4b6..ac3fec03926a 100644
> --- a/arch/powerpc/mm/book3s64/radix_tlb.c
> +++ b/arch/powerpc/mm/book3s64/radix_tlb.c
> @@ -661,6 +661,7 @@ static void do_exit_flush_lazy_tlb(void *arg)
> mmgrab(&init_mm);
> current->active_mm = &init_mm;
> switch_mm_irqs_off(mm, &init_mm, current);
> + exit_lazy_tlb(mm, current);
> mmdrop(mm);
> }
>
> diff --git a/fs/exec.c b/fs/exec.c
> index 547a2390baf5..4b4dea1bb7ba 100644
> --- a/fs/exec.c
> +++ b/fs/exec.c
> @@ -1017,6 +1017,8 @@ static int exec_mmap(struct mm_struct *mm)
> if (!IS_ENABLED(CONFIG_ARCH_WANT_IRQS_OFF_ACTIVATE_MM))
> local_irq_enable();
> activate_mm(active_mm, mm);
> + if (!old_mm)
> + exit_lazy_tlb(active_mm, tsk);
> if (IS_ENABLED(CONFIG_ARCH_WANT_IRQS_OFF_ACTIVATE_MM))
> local_irq_enable();
> tsk->mm->vmacache_seqnum = 0;
> @@ -1028,9 +1030,9 @@ static int exec_mmap(struct mm_struct *mm)
> setmax_mm_hiwater_rss(&tsk->signal->maxrss, old_mm);
> mm_update_next_owner(old_mm);
> mmput(old_mm);
> - return 0;
> + } else {
> + mmdrop(active_mm);
> }
> - mmdrop(active_mm);
This looks like an unrelated change.
> return 0;
> }
>
> diff --git a/include/asm-generic/mmu_context.h b/include/asm-generic/mmu_context.h
> index 91727065bacb..4626d0020e65 100644
> --- a/include/asm-generic/mmu_context.h
> +++ b/include/asm-generic/mmu_context.h
> @@ -24,6 +24,27 @@ static inline void enter_lazy_tlb(struct mm_struct *mm,
> }
> #endif
>
> +/*
> + * exit_lazy_tlb - Called after switching away from a lazy TLB mode mm.
> + *
> + * mm: the lazy mm context that was switched
> + * tsk: the task that was switched to (with a non-lazy mm)
> + *
> + * mm may equal tsk->mm.
> + * mm and tsk->mm will not be NULL.
> + *
> + * Note this is not symmetrical to enter_lazy_tlb, this is not
> + * called when tasks switch into the lazy mm, it's called after the
> + * lazy mm becomes non-lazy (either switched to a different mm or the
> + * owner of the mm returns).
> + */
> +#ifndef exit_lazy_tlb
> +static inline void exit_lazy_tlb(struct mm_struct *mm,
Maybe name this parameter prev_lazy_mm?
