Hi, this is my first attempt to add support for non-CPU TLBs to the MMU-Notifier framework. This will be used by the AMD IOMMU driver for the next generation of hardware. The next version of the AMD IOMMU can walk page-tables in AMD64 long-mode format (with setting accessed/dirty-bits atomically) and save the translations in its own TLB. Page faulting for IO devices is supported too. This will be used to let hardware devices share page-tables with CPU processes and access their memory directly. Please look at http://support.amd.com/us/Processor_TechDocs/48882.pdf for details. The link points to the specification for the next version of the IOMMU. The current problem with the MMU-Notifiers is the definition of the invalidate_range_start/end call-backs. The invalidate_range_start() function is called when the pages are still mapped while invalidate_range_end() is called when the pages are unmapped and already freed. This is too late to flush any external TLB. The TLB needs to be flushed when the pages are unmapped but not yet freed. Holding a reference to the pages in the range is no option because the subsystem has to keep the pointer to these pages then. This doesn't really scale with the size of the range to be unmapped. A related problem is that the memory to hold the page-pointers can't be easily allocated in the invalidate_range_start() notifier because it is not allowed to preempt (because it is called under rcu_read_lock). A simpler approach is to add a new notifier which is called between invalidate_range_start/end by the VM every time it is about to free pages that it has unmapped. This is the same point in time when the VM would flush the TLB on any remote CPUs, so this is a logical point to also flush any non-CPU TLB for an MM. This approach is implemented by this patch-set. As a side requirement it is necessary to disable the tlb_fast_mode when an mm has notifers. The first patch in this series implements this. The second patch implements the new callback into the MMU-Notifier framework and the last patch adds the calls to the notifier into the MM code where necessary. A known limitation of this patch-set is that it only disables tlb_fast_mode for the generic implementation of mmu_gather. I will add support for the architectures with their own implementation in the next version. I wanted to keep this one small to get your feedback on the general idea. Any feedback greatly appreciated. Thanks, Joerg Diffstat: include/asm-generic/tlb.h | 2 +- include/linux/mmu_notifier.h | 33 ++++++++++++++++++++++++++++----- mm/hugetlb.c | 1 + mm/memory.c | 13 ++++++++++++- mm/mmu_notifier.c | 13 +++++++++++++ 5 files changed, 55 insertions(+), 7 deletions(-) -- 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/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>