2019-07-30 05:57:51

by Christoph Hellwig

Subject: [PATCH 10/13] mm: 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.

Signed-off-by: Christoph Hellwig <[email protected]>
---
mm/hmm.c | 29 ++++++++++++++++-------------
1 file changed, 16 insertions(+), 13 deletions(-)

diff --git a/mm/hmm.c b/mm/hmm.c
index e63ab7f11334..4d3bd41b6522 100644
--- a/mm/hmm.c
+++ b/mm/hmm.c
@@ -455,15 +455,6 @@ 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,
@@ -700,10 +691,19 @@ static int hmm_vma_walk_pmd(pmd_t *pmdp,
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;
@@ -765,6 +765,9 @@ static int hmm_vma_walk_pud(pud_t *pudp,

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,
--
2.20.1

2019-07-30 18:18:30

by Jason Gunthorpe

Subject: Re: [PATCH 10/13] mm: only define hmm_vma_walk_pud if needed

On Tue, Jul 30, 2019 at 08:52:00AM +0300, Christoph Hellwig wrote:
> 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.
>
> Signed-off-by: Christoph Hellwig <[email protected]>
> ---
> mm/hmm.c | 29 ++++++++++++++++-------------
> 1 file changed, 16 insertions(+), 13 deletions(-)

Reviewed-by: Jason Gunthorpe <[email protected]>

Jason