From c791ace1e747371658237f0d30234fef56c39669 Mon Sep 17 00:00:00 2001
From: Dave Jiang
Date: Fri, 24 Feb 2017 14:57:08 -0800
Subject: mm: replace FAULT_FLAG_SIZE with parameter to huge_fault

Since the introduction of FAULT_FLAG_SIZE to the vm_fault flag, it has
been somewhat painful with getting the flags set and removed at the
correct locations.  More than one kernel oops was introduced due to
difficulties of getting the placement correctly.

Remove the flag values and introduce an input parameter to huge_fault
that indicates the size of the page entry.  This makes the code easier
to trace and should avoid the issues we see with the fault flags where
removal of the flag was necessary in the fallback paths.

Link: http://lkml.kernel.org/r/148615748258.43180.1690152053774975329.stgit@djiang5-desk3.ch.intel.com
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Tested-by: Dan Williams <dan.j.williams@intel.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: Matthew Wilcox <mawilcox@microsoft.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Nilesh Choudhury <nilesh.choudhury@oracle.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
 drivers/dax/dax.c | 18 ++++++++++++------
 1 file changed, 12 insertions(+), 6 deletions(-)

(limited to 'drivers/dax')

diff --git a/drivers/dax/dax.c b/drivers/dax/dax.c
index b90bb301bda0..b75c77254fdb 100644
--- a/drivers/dax/dax.c
+++ b/drivers/dax/dax.c
@@ -538,7 +538,8 @@ static int __dax_dev_pud_fault(struct dax_dev *dax_dev, struct vm_fault *vmf)
 }
 #endif /* !CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
 
-static int dax_dev_fault(struct vm_fault *vmf)
+static int dax_dev_huge_fault(struct vm_fault *vmf,
+		enum page_entry_size pe_size)
 {
 	int rc;
 	struct file *filp = vmf->vma->vm_file;
@@ -550,14 +551,14 @@ static int dax_dev_fault(struct vm_fault *vmf)
 			vmf->vma->vm_start, vmf->vma->vm_end);
 
 	rcu_read_lock();
-	switch (vmf->flags & FAULT_FLAG_SIZE_MASK) {
-	case FAULT_FLAG_SIZE_PTE:
+	switch (pe_size) {
+	case PE_SIZE_PTE:
 		rc = __dax_dev_pte_fault(dax_dev, vmf);
 		break;
-	case FAULT_FLAG_SIZE_PMD:
+	case PE_SIZE_PMD:
 		rc = __dax_dev_pmd_fault(dax_dev, vmf);
 		break;
-	case FAULT_FLAG_SIZE_PUD:
+	case PE_SIZE_PUD:
 		rc = __dax_dev_pud_fault(dax_dev, vmf);
 		break;
 	default:
@@ -568,9 +569,14 @@ static int dax_dev_fault(struct vm_fault *vmf)
 	return rc;
 }
 
+static int dax_dev_fault(struct vm_fault *vmf)
+{
+	return dax_dev_huge_fault(vmf, PE_SIZE_PTE);
+}
+
 static const struct vm_operations_struct dax_dev_vm_ops = {
 	.fault = dax_dev_fault,
-	.huge_fault = dax_dev_fault,
+	.huge_fault = dax_dev_huge_fault,
 };
 
 static int dax_mmap(struct file *filp, struct vm_area_struct *vma)
-- 
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