Have you tried to profile something like umount -l on a large mount tree? You variant causes a shitstorm of schedule work switch to workqueue do actual fs shutdown wake umount(8) up get through wait_for_completion() for every bleeding vfsmount in there. And no, it's *not* guaranteed to be dominated by fs shutdown time. Here's the case where it definitely won't be: mkdir /tmp/a mount --rbind / /tmp/a umount -l /tmp/a All vfsmounts involved are killed off with no fs shutdown. And that's *not* a rare case - exit of the last process in namespace is very likely to look that way too. That's far too heavy. -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
