On Wed, Oct 02, 2013 at 04:27:41PM +0200, Jan Kara wrote: > Hello, > > In my quest for changing locking around page faults to make things easier for > filesystems I found out get_user_pages() users could use a cleanup. The > knowledge about necessary locking for get_user_pages() is in tons of places in > drivers and quite a few of them actually get it wrong (don't have mmap_sem when > calling get_user_pages() or hold mmap_sem when calling copy_from_user() in the > surrounding code). Rather often this actually doesn't seem necessary. This > patch series converts lots of places to use either get_user_pages_fast() > or a new simple wrapper get_user_pages_unlocked() to remove the knowledge > of mmap_sem from the drivers. I'm still looking into converting a few remaining > drivers (most notably v4l2) which are more complex. Even looking over the kerneldoc comment next to it I still fail to understand when you'd want to use get_user_pages_fast and when not. This isn't meant as an argument against your series, but maybe a hint that we'd need further work in this direction. -- 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>