Re: Deadlock on the mm->mmap_sem

[David Howells]

Andrea Arcangeli <[e-mail]> wrote:
> yes, one solution to the latency problem without writing the
> ugly code would be simply to add a per-process counter to pass to a
> modified rwsem api, then to hide the trickery in a mm_down_read macro.
> such way it will be recursive _and_ fair.

You'd need a counter per-process per-mm_struct. Otherwise you couldn't do a
recursive read lock simultaneously in two or more different processes, and
also allow any one process to lock multiple mm_structs.

David