Hi Jon, Steve is currently away, but should be back in the office next week. On Fri, Feb 27, 2015 at 12:42:30PM +0000, Jon Masters wrote: > On 09/26/2014 10:03 AM, Steve Capper wrote: > > > This series implements general forms of get_user_pages_fast and > > __get_user_pages_fast in core code and activates them for arm and arm64. > > > > These are required for Transparent HugePages to function correctly, as > > a futex on a THP tail will otherwise result in an infinite loop (due to > > the core implementation of __get_user_pages_fast always returning 0). > > > > Unfortunately, a futex on THP tail can be quite common for certain > > workloads; thus THP is unreliable without a __get_user_pages_fast > > implementation. > > > > This series may also be beneficial for direct-IO heavy workloads and > > certain KVM workloads. > > > > I appreciate that the merge window is coming very soon, and am posting > > this revision on the off-chance that it gets the nod for 3.18. (The changes > > thus far have been minimal and the feedback I've got has been mainly > > positive). > > Head's up: these patches are currently implicated in a rare-to-trigger > hang that we are seeing on an internal kernel. An extensive effort is > underway to confirm whether these are the cause. Will followup. I'm currently investigating an intermittent memory corruption issue in v4.0-rc1 I'm able to trigger on Seattle with 4K pages and 48-bit VA, which may or may not be related. Sometimes it results in a hang (when the vectors get corrupted and the CPUs get caught in a recursive exception loop). Which architecture(s) are you hitting this on? Which configurations configuration(s)? What are you using to tickle the issue? Thanks, Mark. -- 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>