Some person already reported this. I'm having the same problem. http://marc.info/?l=linux-ext4&m=122557056518246&w=2 rtorrent is a bittorrent client that makes heavy use of mmap instead of read/write to avoid needless duplication of data. It has exposed other bugs in the past (mmap bug in 2.6.19). http://libtorrent.rakshasa.no Downloading a big torrent (>2GB) with rtorrent triggers it more times than not. The bigger the torrent, the higher the likeliness of failure. When the torrent is finished, if a hash check is forced by pressing control-r on the torrent, some blocks will fail. The torrent doesn't need to be a single file, but can be a series of small files that add up enough. Downloading on ext3 or XFS instead is 100% fine. I've discarded posix fallocate as the culprit by building rtorrent without the patch that adds that (and doing a du just in case, definitively not preallocating). Filesystem is ~1.4TB. I've also reproduced it on a 200GB partition. The system is: Linux kaguya 2.6.27.4 #1 SMP Mon Oct 27 14:43:19 UTC 2008 x86_64 Intel(R) Atom(TM) CPU 330 @ 1.60GHz GenuineIntel GNU/Linux No kernel patches were applied. -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html