On Thu, Mar 03, 2016 at 07:51:50PM +0300, Kirill A. Shutemov wrote: > Truncate and punch hole that only cover part of THP range is implemented > by zero out this part of THP. > > This have visible effect on fallocate(FALLOC_FL_PUNCH_HOLE) behaviour. > As we don't really create hole in this case, lseek(SEEK_HOLE) may have > inconsistent results depending what pages happened to be allocated. > Not sure if it should be considered ABI break or not. Looks like this shouldn't be a problem. man 2 fallocate: Within the specified range, partial filesystem blocks are zeroed, and whole filesystem blocks are removed from the file. After a successful call, subsequent reads from this range will return zeroes. It means we effectively have 2M filesystem block size. And I don't see any guarantee about subsequent lseek(SEEK_HOLE) beheviour. -- Kirill A. Shutemov -- 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>