linux-kernel - [PATCH 1/2] mm: Make follow_pte

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Message-Id: <20171219165823.24243-1-willy@infradead.org>
Date:   Tue, 19 Dec 2017 08:58:22 -0800
From:   Matthew Wilcox <willy@...radead.org>
To:     linux-kernel@...r.kernel.org,
        Ross Zwisler <ross.zwisler@...ux.intel.com>,
        Dave Hansen <dave.hansen@...el.com>, linux-mm@...ck.org,
        Josh Triplett <josh@...htriplett.org>
Cc:     Matthew Wilcox <mawilcox@...rosoft.com>
Subject: [PATCH 1/2] mm: Make follow_pte_pmd an inline

From: Matthew Wilcox <mawilcox@...rosoft.com>

The one user of follow_pte_pmd (dax) emits a sparse warning because
it doesn't know that follow_pte_pmd conditionally returns with the
pte/pmd locked.  The required annotation is already there; it's just
in the wrong file.
---
 include/linux/mm.h | 15 ++++++++++++++-
 mm/memory.c        | 16 +---------------
 2 files changed, 15 insertions(+), 16 deletions(-)

diff --git a/include/linux/mm.h b/include/linux/mm.h
index ea818ff739cd..94a9d2149bd6 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1314,7 +1314,7 @@ int copy_page_range(struct mm_struct *dst, struct mm_struct *src,
 			struct vm_area_struct *vma);
 void unmap_mapping_range(struct address_space *mapping,
 		loff_t const holebegin, loff_t const holelen, int even_cows);
-int follow_pte_pmd(struct mm_struct *mm, unsigned long address,
+int __follow_pte_pmd(struct mm_struct *mm, unsigned long address,
 			     unsigned long *start, unsigned long *end,
 			     pte_t **ptepp, pmd_t **pmdpp, spinlock_t **ptlp);
 int follow_pfn(struct vm_area_struct *vma, unsigned long address,
@@ -1324,6 +1324,19 @@ int follow_phys(struct vm_area_struct *vma, unsigned long address,
 int generic_access_phys(struct vm_area_struct *vma, unsigned long addr,
 			void *buf, int len, int write);
 
+static inline int follow_pte_pmd(struct mm_struct *mm, unsigned long address,
+			     unsigned long *start, unsigned long *end,
+			     pte_t **ptepp, pmd_t **pmdpp, spinlock_t **ptlp)
+{
+	int res;
+
+	/* (void) is needed to make gcc happy */
+	(void) __cond_lock(*ptlp,
+			   !(res = __follow_pte_pmd(mm, address, start, end,
+						    ptepp, pmdpp, ptlp)));
+	return res;
+}
+
 static inline void unmap_shared_mapping_range(struct address_space *mapping,
 		loff_t const holebegin, loff_t const holelen)
 {
diff --git a/mm/memory.c b/mm/memory.c
index cfaba6287702..cb433662af21 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -4201,7 +4201,7 @@ int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address)
 }
 #endif /* __PAGETABLE_PMD_FOLDED */
 
-static int __follow_pte_pmd(struct mm_struct *mm, unsigned long address,
+int __follow_pte_pmd(struct mm_struct *mm, unsigned long address,
 			    unsigned long *start, unsigned long *end,
 			    pte_t **ptepp, pmd_t **pmdpp, spinlock_t **ptlp)
 {
@@ -4278,20 +4278,6 @@ static inline int follow_pte(struct mm_struct *mm, unsigned long address,
 	return res;
 }
 
-int follow_pte_pmd(struct mm_struct *mm, unsigned long address,
-			     unsigned long *start, unsigned long *end,
-			     pte_t **ptepp, pmd_t **pmdpp, spinlock_t **ptlp)
-{
-	int res;
-
-	/* (void) is needed to make gcc happy */
-	(void) __cond_lock(*ptlp,
-			   !(res = __follow_pte_pmd(mm, address, start, end,
-						    ptepp, pmdpp, ptlp)));
-	return res;
-}
-EXPORT_SYMBOL(follow_pte_pmd);
-
 /**
  * follow_pfn - look up PFN at a user virtual address
  * @vma: memory mapping
-- 
2.15.1