On Tue, Aug 29, 2017 at 10:33:52AM +0200, Peter Zijlstra wrote: > On Tue, Aug 29, 2017 at 07:14:37AM +1000, Benjamin Herrenschmidt wrote: > > We'd have to audit archs closely. Things like the page walk cache > > flushing on power etc... > > If you point me where to look, I'll have a poke around. I'm not > quite sure what you mean with pagewalk cache flushing. Your hash thing > flushes everything inside the PTL IIRC and the radix code appears fairly > 'normal'. mpe helped me out and explained that is the PWC hint to TBLIE. So, you set need_flush_all when you unhook pud/pmd/pte which you then use to set PWC. So free_pgtables() will do the PWC when it unhooks higher level pages. But you're right that there's some issues, free_pgtables() itself doesn't seem to use mm->page_table_lock,pmd->lock _AT_ALL_ to unhook the pages. If it were to do that, things should work fine since those locks would then serialize against the speculative faults, we would never install a page if the VMA would be under tear-down and it would thus not be visible to your caches either. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>
