mm/hmm: only define hmm_vma_walk_pud if needed

We only need the special pud_entry walker if PUD-sized hugepages and pte
mappings are supported, else the common pagewalk code will take care of
the iteration.  Not implementing this callback reduced the amount of code
compiled for non-x86 platforms, and also fixes compile failures with other
architectures when helpers like pud_pfn are not implemented.

Link: https://lore.kernel.org/r/20190806160554.14046-11-hch@lst.de
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jason Gunthorpe <jgg@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>

diff --git a/mm/hmm.c b/mm/hmm.c
index 8d56a43..fb13064 100644 (file)
--- a/mm/hmm.c
+++ b/mm/hmm.c
@@ -456,15 +456,6 @@ static inline uint64_t pmd_to_hmm_pfn_flags(struct hmm_range *range, pmd_t pmd)
                                range->flags[HMM_PFN_VALID];
 }
 
-static inline uint64_t pud_to_hmm_pfn_flags(struct hmm_range *range, pud_t pud)
-{
-       if (!pud_present(pud))
-               return 0;
-       return pud_write(pud) ? range->flags[HMM_PFN_VALID] |
-                               range->flags[HMM_PFN_WRITE] :
-                               range->flags[HMM_PFN_VALID];
-}
-
 static int hmm_vma_handle_pmd(struct mm_walk *walk,
                              unsigned long addr,
                              unsigned long end,
@@ -705,10 +696,19 @@ again:
        return 0;
 }
 
-static int hmm_vma_walk_pud(pud_t *pudp,
-                           unsigned long start,
-                           unsigned long end,
-                           struct mm_walk *walk)
+#if defined(CONFIG_ARCH_HAS_PTE_DEVMAP) && \
+    defined(CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD)
+static inline uint64_t pud_to_hmm_pfn_flags(struct hmm_range *range, pud_t pud)
+{
+       if (!pud_present(pud))
+               return 0;
+       return pud_write(pud) ? range->flags[HMM_PFN_VALID] |
+                               range->flags[HMM_PFN_WRITE] :
+                               range->flags[HMM_PFN_VALID];
+}
+
+static int hmm_vma_walk_pud(pud_t *pudp, unsigned long start, unsigned long end,
+               struct mm_walk *walk)
 {
        struct hmm_vma_walk *hmm_vma_walk = walk->private;
        struct hmm_range *range = hmm_vma_walk->range;
@@ -772,6 +772,9 @@ again:
 
        return 0;
 }
+#else
+#define hmm_vma_walk_pud       NULL
+#endif
 
 static int hmm_vma_walk_hugetlb_entry(pte_t *pte, unsigned long hmask,
                                      unsigned long start, unsigned long end,