I've got an application where a device driver is trying to translate a user memory buffer address into a kernel address. The memory is allocated with shmget() because it is a shared memory segment shared by multiple processes. The underlying allocation is kmalloc. Sometimes my code works, but other times the maplist returned by a call to map_user_kiobuf() contains all zeros. When the code is working, it continues working until after a reboot. The user memory buffer is working properly in the process, but I can not access it from the driver. unsigned int *buffer_address; // address of user memory buffer struct kiobuf *iobuf; map_user_kiobuf(READ, iobuf, (unsigned long) buffer_address, 1); When it fails, iobuf->maplist[0] == 0, iobuf->offset == 0, and page_address(iobuf->maplist[0]) == 0. Can someone tell me what else I should be doing or checking?, or if there is more information I can provide to help fix this? Dave Z. -- Kernelnewbies: Help each other learn about the Linux kernel. Archive: http://mail.nl.linux.org/kernelnewbies/ FAQ: http://kernelnewbies.org/faq/
