[PATCH v2] mm: Change return type to vm_fault_t

[PATCH v2] mm: Change return type to vm_fault_t

[Souptick Joarder]

Use new return type vm_fault_t for fault handler
in struct vm_operations_struct. For now, this is
just documenting that the function returns a 
VM_FAULT value rather than an errno.  Once all
instances are converted, vm_fault_t will become
a distinct type.

commit 1c8f422059ae ("mm: change return type to
vm_fault_t")

Signed-off-by: Souptick Joarder <jrdr.linux@gmail.com>
Reviewed-by: Matthew Wilcox <mawilcox@microsoft.com>
---
v2: Updated the change log

 mm/hugetlb.c | 2 +-
 mm/mmap.c    | 4 ++--
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 7c204e3..acb432a 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -3158,7 +3158,7 @@ static int hugetlb_vm_op_split(struct vm_area_struct *vma, unsigned long addr)
  * hugegpage VMA.  do_page_fault() is supposed to trap this, so BUG is we get
  * this far.
  */
-static int hugetlb_vm_op_fault(struct vm_fault *vmf)
+static vm_fault_t hugetlb_vm_op_fault(struct vm_fault *vmf)
 {
 	BUG();
 	return 0;
diff --git a/mm/mmap.c b/mm/mmap.c
index 9efdc021..ac41b34 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -3208,7 +3208,7 @@ void vm_stat_account(struct mm_struct *mm, vm_flags_t flags, long npages)
 		mm->data_vm += npages;
 }
 
-static int special_mapping_fault(struct vm_fault *vmf);
+static vm_fault_t special_mapping_fault(struct vm_fault *vmf);
 
 /*
  * Having a close hook prevents vma merging regardless of flags.
@@ -3247,7 +3247,7 @@ static int special_mapping_mremap(struct vm_area_struct *new_vma)
 	.fault = special_mapping_fault,
 };
 
-static int special_mapping_fault(struct vm_fault *vmf)
+static vm_fault_t special_mapping_fault(struct vm_fault *vmf)
 {
 	struct vm_area_struct *vma = vmf->vma;
 	pgoff_t pgoff;
-- 
1.9.1

Re: [PATCH v2] mm: Change return type to vm_fault_t

[Matthew Wilcox]

On Fri, May 11, 2018 at 11:36:39PM +0530, Souptick Joarder wrote:
>  mm/hugetlb.c | 2 +-
>  mm/mmap.c    | 4 ++--
>  2 files changed, 3 insertions(+), 3 deletions(-)

Don't we also need to convert include/linux/mm_types.h:

@@ -621,7 +621,7 @@ struct vm_special_mapping {
         * If non-NULL, then this is called to resolve page faults
         * on the special mapping.  If used, .pages is not checked.
         */
-       int (*fault)(const struct vm_special_mapping *sm,
+       vm_fault_t (*fault)(const struct vm_special_mapping *sm,
                     struct vm_area_struct *vma,
                     struct vm_fault *vmf);
 
or are you leaving that for a later patch?

Re: [PATCH v2] mm: Change return type to vm_fault_t

[Souptick Joarder]

On Fri, May 11, 2018 at 11:45 PM, Matthew Wilcox <willy@infradead.org> wrote:
> On Fri, May 11, 2018 at 11:36:39PM +0530, Souptick Joarder wrote:
>>  mm/hugetlb.c | 2 +-
>>  mm/mmap.c    | 4 ++--
>>  2 files changed, 3 insertions(+), 3 deletions(-)
>
> Don't we also need to convert include/linux/mm_types.h:
>
> @@ -621,7 +621,7 @@ struct vm_special_mapping {
>          * If non-NULL, then this is called to resolve page faults
>          * on the special mapping.  If used, .pages is not checked.
>          */
> -       int (*fault)(const struct vm_special_mapping *sm,
> +       vm_fault_t (*fault)(const struct vm_special_mapping *sm,
>                      struct vm_area_struct *vma,
>                      struct vm_fault *vmf);
>
> or are you leaving that for a later patch?

Ahh, I didn't realise. No I think, we can add it as part of this
patch. Will send v3.