linux-kernel - [PATCH 10/13] mm: only define hmm_vma_walk

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Message-Id: <20190730055203.28467-11-hch@lst.de>
Date:   Tue, 30 Jul 2019 08:52:00 +0300
From:   Christoph Hellwig <hch@....de>
To:     Jérôme Glisse <jglisse@...hat.com>,
        Jason Gunthorpe <jgg@...lanox.com>,
        Ben Skeggs <bskeggs@...hat.com>,
        Felix Kuehling <Felix.Kuehling@....com>
Cc:     Ralph Campbell <rcampbell@...dia.com>, linux-mm@...ck.org,
        nouveau@...ts.freedesktop.org, dri-devel@...ts.freedesktop.org,
        amd-gfx@...ts.freedesktop.org, linux-kernel@...r.kernel.org
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 <hch@....de>
---
 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