On Wed, Jun 01, 2011 at 09:58:18AM -0700, Hugh Dickins wrote: > (i915 isn't really doing hole-punching there, I think it just found it > a useful interface to remove the page-and-swapcache without touching > i_size. Parentheses because it makes no difference to your point.) Keeping i_size while removing pages on tmpfs fits the defintion of hole punching for me. Not that it matters anyway. > When I say "shmem", I am including the !SHMEM-was-TINY_SHMEM case too, > which goes to ramfs. Currently i915 has been configured to disable that > possibility, though we insisted on it originally: there may or may not be > good reason for disabling it - may just be a side-effect of the rather > twisted unintuitive SHMEM/TMPFS dependencies. Hmm, the two different implementations make everything harder. Also because we don't even implement the hole punching in !SHMEM tmpfs. > Fine, I'll add tmpfs PUNCH_HOLE later on. And wire up madvise MADV_REMOVE > to fallocate PUNCH_HOLE, yes? Yeah. One thing I've noticed is that the hole punching doesn't seem to do the unmap_mapping_range. It might be worth to audit that from the VM point of view. > Would you like me to remove the ->truncate_range method from > inode_operations completely? Doing that would be nice. Do we always have the required file struct for ->fallocate in the callers? -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>