linux-kernel - [PATCH 1/3] mm: Introduce vmf_insert_pfn

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Date:   Tue,  3 Jul 2018 05:39:08 -0700
From:   Matthew Wilcox <willy@...radead.org>
To:     Andy Lutomirski <luto@...capital.net>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        "H. Peter Anvin" <hpa@...or.com>
Cc:     Matthew Wilcox <willy@...radead.org>,
        Souptick Joarder <jrdr.linux@...il.com>, x86@...nel.org,
        linux-kernel@...r.kernel.org, brajeswar.linux@...il.com,
        Sabyasachi Gupta <sabyasachi.linux@...il.com>
Subject: [PATCH 1/3] mm: Introduce vmf_insert_pfn_prot

Like vm_insert_pfn_prot(), but returns a vm_fault_t instead of an errno.
Also unexport vm_insert_pfn_prot as it has no modular users.

Signed-off-by: Matthew Wilcox <willy@...radead.org>
---
 include/linux/mm.h |  2 ++
 mm/memory.c        | 47 ++++++++++++++++++++++++++++++----------------
 2 files changed, 33 insertions(+), 16 deletions(-)

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 1a9d6bd97f00..3cb763a38642 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -2441,6 +2441,8 @@ int vm_insert_pfn(struct vm_area_struct *vma, unsigned long addr,
 			unsigned long pfn);
 int vm_insert_pfn_prot(struct vm_area_struct *vma, unsigned long addr,
 			unsigned long pfn, pgprot_t pgprot);
+vm_fault_t vmf_insert_pfn_prot(struct vm_area_struct *vma, unsigned long addr,
+			unsigned long pfn, pgprot_t pgprot);
 int vm_insert_mixed(struct vm_area_struct *vma, unsigned long addr,
 			pfn_t pfn);
 vm_fault_t vmf_insert_mixed_mkwrite(struct vm_area_struct *vma,
diff --git a/mm/memory.c b/mm/memory.c
index b9ebd883e27c..caecb4d995ac 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1852,21 +1852,6 @@ int vm_insert_pfn(struct vm_area_struct *vma, unsigned long addr,
 }
 EXPORT_SYMBOL(vm_insert_pfn);
 
-/**
- * vm_insert_pfn_prot - insert single pfn into user vma with specified pgprot
- * @vma: user vma to map to
- * @addr: target user address of this page
- * @pfn: source kernel pfn
- * @pgprot: pgprot flags for the inserted page
- *
- * This is exactly like vm_insert_pfn, except that it allows drivers to
- * to override pgprot on a per-page basis.
- *
- * This only makes sense for IO mappings, and it makes no sense for
- * cow mappings.  In general, using multiple vmas is preferable;
- * vm_insert_pfn_prot should only be used if using multiple VMAs is
- * impractical.
- */
 int vm_insert_pfn_prot(struct vm_area_struct *vma, unsigned long addr,
 			unsigned long pfn, pgprot_t pgprot)
 {
@@ -1893,7 +1878,37 @@ int vm_insert_pfn_prot(struct vm_area_struct *vma, unsigned long addr,
 
 	return ret;
 }
-EXPORT_SYMBOL(vm_insert_pfn_prot);
+
+/**
+ * vmf_insert_pfn_prot - insert single pfn into user vma with specified pgprot
+ * @vma: user vma to map to
+ * @addr: target user address of this page
+ * @pfn: source kernel pfn
+ * @pgprot: pgprot flags for the inserted page
+ *
+ * This is exactly like vmf_insert_pfn(), except that it allows drivers to
+ * to override pgprot on a per-page basis.
+ *
+ * This only makes sense for IO mappings, and it makes no sense for
+ * COW mappings.  In general, using multiple vmas is preferable;
+ * vm_insert_pfn_prot should only be used if using multiple VMAs is
+ * impractical.
+ *
+ * Return: vm_fault_t value.
+ */
+vm_fault_t vmf_insert_pfn_prot(struct vm_area_struct *vma, unsigned long addr,
+			unsigned long pfn, pgprot_t pgprot)
+{
+	int err = vm_insert_pfn_prot(vma, addr, pfn, pgprot);
+
+	if (err == -ENOMEM)
+		return VM_FAULT_OOM;
+	if (err < 0 && err != -EBUSY)
+		return VM_FAULT_SIGBUS;
+
+	return VM_FAULT_NOPAGE;
+}
+EXPORT_SYMBOL(vmf_insert_pfn_prot);
 
 static bool vm_mixed_ok(struct vm_area_struct *vma, pfn_t pfn)
 {
-- 
2.18.0