Re: [PATCHv5.1 04/13] x86/mm: Handle LAM on context switch

[Kirill A. Shutemov]

On Wed, Jul 20, 2022 at 10:57:01AM +0200, Alexander Potapenko wrote:
> >         /*
> > @@ -491,6 +493,8 @@ void switch_mm_irqs_off(struct mm_struct *prev, struct mm_struct *next,
> >  {
> >         struct mm_struct *real_prev = this_cpu_read(cpu_tlbstate.loaded_mm);
> >         u16 prev_asid = this_cpu_read(cpu_tlbstate.loaded_mm_asid);
> > +       unsigned long prev_lam = tlbstate_lam_cr3_mask();
> Note: this variable is never used if CONFIG_DEBUG_VM is off.

Good point. I will add this:

diff --git a/arch/x86/mm/tlb.c b/arch/x86/mm/tlb.c
index 4c93f87a8928..5e9ed9f55c36 100644
--- a/arch/x86/mm/tlb.c
+++ b/arch/x86/mm/tlb.c
@@ -558,6 +558,7 @@ void switch_mm_irqs_off(struct mm_struct *prev, struct mm_struct *next,
 	if (real_prev == next) {
 		VM_WARN_ON(this_cpu_read(cpu_tlbstate.ctxs[prev_asid].ctx_id) !=
 			   next->context.ctx_id);
+		VM_WARN_ON(prev_lam != new_lam);

 		/*
 		 * Even in lazy TLB mode, the CPU should stay set in the
-- 
 Kirill A. Shutemov