I'm having serious latency problems due to mmap_sem contention. I have a real-time thread that has (soft) page faults on locked pages, and it blocks for multiple milliseconds on (call_rwsem_down_read_failed do_page_fault page_fault). Can this be fixed? Some ideas: 1. Drop mmap_sem during the filesystem part of mmap and munmap. (MAP_POPULATE in particular is a disaster -- using it will easily increase latency from a few milliseconds to a respectable fraction of a second.) 2. Come up with some way to lock specific vm_area_structs for read access without taking mmap_sem at all. This looks unpleasant with the current rbtree structure -- something like a radix tree might work much better if the nodes were to contain their own locks. --Andy -- Andy Lutomirski AMA Capital Management, LLC -- 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>