On 2020-08-12 16:39:41 [+0200], Thomas Gleixner wrote: > Sebastian, Hi tglx,
> Sebastian Andrzej Siewior <[email protected]> writes: > > > The pte lock is never acquired from an IRQ-off region so it does not > > require the interrupts to be disabled. > > I doubt that this is true. It surely is acquired within other locks > which might be taken with spin_lock_irq(). Which is completely fine on > RT. > > But that's not the point. The point is that pte_lock() does not require > to be taken with interrupts disabled. The IRQ-off vs in-IRQ working was chosen poorly. > Please be precise about these kind of things. Handwavy descriptions > cause more problems than they solve. > > > RT complains here because the spinlock_t must not be acquired with > > disabled interrupts. > > > > use_temporary_mm() expects interrupts to be off because it invokes > > switch_mm_irqs_off() and uses per-CPU (current active mm) data. > > > > Move local_irq_save() after the the pte lock has been acquired. Move > > local_irq_restore() after the pte lock has been released. > > While part 1 is correct, part 2 is the exact opposite of what the patch > does. > > Move the PTE lock handling outside the interrupt disabled region. > > describes precisely what this is about without any gory details which > can be seen in the patch itself. Hmm? Oki reworded. > Thanks, > > tglx Sebastian
