On Wed, Jan 06, 2016 at 10:35:05AM -0500, Alan Stern wrote: > Indeed, the I/O operations we are using with mmap here are not reads or > writes; they are ioctls. As far as I know, the kernel doesn't have any > defined interface for zerocopy ioctls. IF it was using mmap for I/O it would read in through the page fault handler an then mark the page dirty for writeback by the VM. Thats clearly not the case. Instead it's using mmap on a file as a pecial purpose anonymous memory allocator, bypassing the VM and VM policies, including allowing to pin kernel memory that way. -- 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>