> We are aware that the shared memory structure in the IPC array, > has a pointer to the inode which has a cyclic link list of > vm_area_structs of all processes that have attached to that shared > region. Is this array (vm_next_share or vm_next_prev) really used > apart from update_mmu_cache or vmtruncate_list?? The vm_next_share and vm_pprev_share pointers are not for shared memory only. They are used to keep track of shared file mappings also. And vmtruncate_list() is a _real_ use for them: if more than one process is mapping the same file and the file got modified (truncated in this case) some way of updating the vma's of all those processes is needed. BTW, I didn't get which IPC array you are refering to. > Also when and where are the shmem_file_operations like > shmem_file_read, shmem_file_map, etc invoked?? Are they by any > chance related to accessing the shared memory used in shmget, > shmat??? Or shm_open, shm_link?? If you are using shmget(), shmat(), etc. shmem_file_opearations are not used. sys_shmget() does get an inode from the shm filesystem, but it replaces the file operations with shm_file_operations. I guess anonymous mmaps (mmapping /dev/zero) and creating/using files in /dev/shm will use shmem_file_operations. Hope this helps, Ravi. __________________________________________________ Do you Yahoo!? Y! Web Hosting - Let the expert host your web site http://webhosting.yahoo.com/ -- Kernelnewbies: Help each other learn about the Linux kernel. Archive: http://mail.nl.linux.org/kernelnewbies/ FAQ: http://kernelnewbies.org/faq/
