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This is done using two Rust types: > > * Mm - represents an mm_struct where you don't know anything about the > value of mm_users. > * MmWithUser - represents an mm_struct where you know at compile time > that mm_users is non-zero. > > This allows us to encode in the type system whether a method requires > that mm_users is non-zero or not. For instance, you can always call > `mmget_not_zero` but you can only call `mmap_read_lock` when mm_users is > non-zero. > > It's possible to access current->mm without a refcount increment, but > that is added in a later patch of this series. > > Acked-by: Lorenzo Stoakes (for mm bits) > Signed-off-by: Alice Ryhl > --- It might be good to add some #Examples similar to kernel/task.rs Acked-by: Balbir Singh