> On May 25, 2017, at 5:47 PM, Andy Lutomirski <luto@xxxxxxxxxx> wrote:
>
> On a remote TLB flush, we leave_mm() if we're TLBSTATE_LAZY. For a
> local flush_tlb_mm_range(), we leave_mm() if !current->mm. These
> are approximately the same condition -- the scheduler sets lazy TLB
> mode when switching to a thread with no mm.
>
> I'm about to merge the local and remote flush code, but for ease of
> verifying and bisecting the patch, I want the local and remote flush
> behavior to match first. This patch changes the local code to match
> the remote code.
>
> Cc: Rik van Riel <riel@xxxxxxxxxx>
> Cc: Dave Hansen <dave.hansen@xxxxxxxxx>
> Cc: Nadav Amit <namit@xxxxxxxxxx>
> Cc: Michal Hocko <mhocko@xxxxxxxx>
> Cc: Arjan van de Ven <arjan@xxxxxxxxxxxxxxx>
> Signed-off-by: Andy Lutomirski <luto@xxxxxxxxxx>
> ---
> arch/x86/mm/tlb.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/x86/mm/tlb.c b/arch/x86/mm/tlb.c
> index 776469cc54e0..3143c9a180e5 100644
> --- a/arch/x86/mm/tlb.c
> +++ b/arch/x86/mm/tlb.c
> @@ -311,7 +311,7 @@ void flush_tlb_mm_range(struct mm_struct *mm, unsigned long start,
> goto out;
> }
>
> - if (!current->mm) {
> + if (this_cpu_read(cpu_tlbstate.state) != TLBSTATE_OK) {
> leave_mm(smp_processor_id());
Maybe it is an overkill, but you may want to have two variants: leave_mm()
and leave_mm_irq_off(). Currently, leave_mm() does not disable IRQs, but
in patch 6 it does. Here you indeed need to disable IRQs, but the cases
in prior to this patch - you do not.
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