mm: Allow the [page|pfn]_mkwrite callbacks to drop the mmap_sem

Driver fault callbacks are allowed to drop the mmap_sem when expecting
long hardware waits to avoid blocking other mm users. Allow the mkwrite
callbacks to do the same by returning early on VM_FAULT_RETRY.

In particular we want to be able to drop the mmap_sem when waiting for
a reservation object lock on a GPU buffer object. These locks may be
held while waiting for the GPU.

Cc: Andrew Morton <[email protected]>
Cc: Matthew Wilcox <[email protected]>
Cc: Will Deacon <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Rik van Riel <[email protected]>
Cc: Minchan Kim <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: Huang Ying <[email protected]>
Cc: Souptick Joarder <[email protected]>
Cc: "Jérôme Glisse" <[email protected]>
Cc: [email protected]
Cc: [email protected]

Signed-off-by: Thomas Hellstrom <[email protected]>
Reviewed-by: Ralph Campbell <[email protected]>

0 files changed, 0 insertions, 0 deletions