[ added Kirill ]
On Sat, Nov 10, 2018 at 4:19 PM Andy Lutomirski luto@amacapital.net wrote:
On Nov 10, 2018, at 3:57 PM, Dan Williams dan.j.williams@intel.com wrote:
On Fri, Nov 9, 2018 at 4:22 PM Andy Lutomirski luto@amacapital.net wrote:
On Nov 9, 2018, at 4:05 PM, Dan Williams dan.j.williams@intel.com wrote:
Commit f77084d96355 "x86/mm/pat: Disable preemption around __flush_tlb_all()" addressed a case where __flush_tlb_all() is called without preemption being disabled. It also left a warning to catch other cases where preemption is not disabled. That warning triggers for the memory hotplug path which is also used for persistent memory enabling:
I don’t think I agree with the patch. If you call __flush_tlb_all() in a context where you might be *migrated*, then there’s a bug. We could change the code to allow this particular use by checking that we haven’t done SMP init yet, perhaps.
Hmm, are saying the entire kernel_physical_mapping_init() sequence needs to run with pre-emption disabled?
If it indeed can run late in boot or after boot, then it sure looks buggy. Either the __flush_tlb_all() should be removed or it should be replaced with flush_tlb_kernel_range(). It’s unclear to me why a flush is needed at all, but if it’s needed, surely all CPUs need flushing.
Yeah, I don't think __flush_tlb_all() is needed at kernel_physical_mapping_init() time, and at kernel_physical_mapping_remove() time we do a full flush_tlb_all().
Kirill?