On Fri, Aug 11, 2017 at 12:22:56PM +0200, Andrea Arcangeli wrote: > disk block? This would happen on ext4 as well if mounted with -o > journal=data instead of -o journal=ordered in fact, perhaps you simply Oops above I meant journal=writeback, journal=data is even stronger than journal=ordered of course. And I shall clarify further that old disk content can only showup legitimately on journal=writeback after a hard reboot or crash or in general an unclean unmount. Even if there's no journaling at all (i.e. ext2/vfat) old disk content cannot be shown at any given time no matter what if there's no unclean unmount that requires a journal reply. This theory of a completely unrelated fs bug showing you disk content as result of the OOM reaper induced SIGBUS interrupting a copy_from_user at its very start, is purely motivated by the fact like Michal I didn't see much explanation on the VM side that could cause those not-zero not-0xff values showing up in the buffer of the write syscall. You can try to change fs and see if it happens again to rule it out. If it always happens regardless of the filesystem used, then it's likely not a fs bug of course. You've got an entire and aligned 4k fs block showing up that data. -- 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>
