From: David Hildenbrand [mailto:dahi@xxxxxxxxxxxxxxxxxx] > > From: David Hildenbrand > > ... > > > Although it might not be optimal, but keeping a separate counter for > > > pagefault_disable() as part of the preemption counter seems to be the only > > > doable thing right now. I am not sure if a completely separated counter is even > > > possible, increasing the size of thread_info. > > > > What about adding (say) 0x10000 for the more restrictive test? > > > > David > > > > You mean as part of the preempt counter? > > The current layout (on my branch) is > > * PREEMPT_MASK: 0x000000ff > * SOFTIRQ_MASK: 0x0000ff00 > * HARDIRQ_MASK: 0x000f0000 > * NMI_MASK: 0x00100000 > * PREEMPT_ACTIVE: 0x00200000 > > I would have added > * PAGEFAULT_MASK: 0x03C00000 I'm not sure where you'd need to add the bits. I think the above works because disabling 'HARDIRQ' implicitly disables 'SOFTIRQ' and 'PREEMPT' (etc), so if 256+ threads disable PREEMPT everything still works. So if disabling pagefaults implies that pre-emption is disabled (but SOFTIRQ is still allowed) then you need to insert your bit(s) between 0xff00 and 0x00ff. OTOH if disabling pre-emption implies that pagefaults are disabled then you'd need to use the lsb and change all the above values. Which makes me think that 'PREEMPT_ACTIVE' isn't right at all. Two threads disabling NMIs (or 32 disabling HARDIRQ) won't DTRT. OTOH I'm only guessing at how this is used. David -- To unsubscribe from this list: send the line "unsubscribe linux-arch" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
