mm/hmm: allow snapshot of the special zero page

If a device driver like nouveau tries to use hmm_range_fault() to access
the special shared zero page in system memory, hmm_range_fault() will
return -EFAULT and kill the process.

Allow hmm_range_fault() to return success (0) when the CPU pagetable entry
points to the special shared zero page.

page_to_pfn() and pfn_to_page() are defined on the zero page so just
handle it like any other page.

Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Ralph Campbell <[email protected]>
Reviewed-by: "Jérôme Glisse" <[email protected]>
Acked-by: David Hildenbrand <[email protected]>
Signed-off-by: Jason Gunthorpe <[email protected]>

0 files changed, 0 insertions, 0 deletions