Michal Suchanek <hramrach@xxxxxxxxxx> writes: > The locking order is likely determined by the structure of the union > and not some system-wide order of filesystems so assuming the readonly > layers are locked as well you will probably get a deadlock with > technically correct mount: > > mount -t overlayfs overlayfs -olowerdir=/lower2,upperdir=/upper /tmpoverlay > mount -t overlayfs overlayfs -olowerdir=/lower1,upperdir=/tmpoverlay /overlay > > mount -t overlayfs overlayfs -olowerdir=/lower1,upperdir=/upper2 /tmpoverlay2 > mount -t overlayfs overlayfs -olowerdir=/lower2,upperdir=/tmpoverlay2 /overlay2 > > because now lower1 and lower2 are differently ordered in the two > overlays. Overlayfs never locks both upper and lower at the same time, which means there's no AB-BA locking dependency. The lock orderings are: -> /overlay -> /lower1 -> /tmpoverlay -> /lower2 -> /upper -> /overlay2 -> /lower2 -> /tmpoverlay2 -> /lower1 -> /upper2 As you can see there's no nesting of lower2 and lower1 into each other. When you combine two filesystems, a completely new ordering is created each time, there's no possibility to make an AB-BA nesting. At least I cannot see one. Thanks, Miklos -- 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