mm: make mm->pinned_vm an atomic64 counter

Taking a sleeping lock to _only_ increment a variable is quite the
overkill, and pretty much all users do this. Furthermore, some drivers
(ie: infiniband and scif) that need pinned semantics can go to quite
some trouble to actually delay via workqueue (un)accounting for pinned
pages when not possible to acquire it.

By making the counter atomic we no longer need to hold the mmap_sem and
can simply some code around it for pinned_vm users. The counter is 64-bit
such that we need not worry about overflows such as rdma user input
controlled from userspace.

Reviewed-by: Ira Weiny <[email protected]>
Reviewed-by: Christoph Lameter <[email protected]>
Reviewed-by: Daniel Jordan <[email protected]>
Reviewed-by: Jan Kara <[email protected]>
Signed-off-by: Davidlohr Bueso <[email protected]>
Signed-off-by: Jason Gunthorpe <[email protected]>

0 files changed, 0 insertions, 0 deletions