mm: trim __do_fault() arguments

Use vm_fault structure to pass cow_page, page, and entry in and out of
the function.

That reduces number of __do_fault() arguments from 4 to 1.

Link: http://lkml.kernel.org/r/1479460644-25076-6-git-send-email-jack@suse.cz
Signed-off-by: Jan Kara <jack@suse.cz>
Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 29 insertions, 38 deletions

diff --git a/mm/memory.c b/mm/memory.c
index cbc6d47fda73..78b81e8984df 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -2844,26 +2844,22 @@ oom:
  * released depending on flags and vma->vm_ops->fault() return value.
  * See filemap_fault() and __lock_page_retry().
  */
-static int __do_fault(struct vm_fault *vmf, struct page *cow_page,
-                      struct page **page, void **entry)
+static int __do_fault(struct vm_fault *vmf)
 {
         struct vm_area_struct *vma = vmf->vma;
         int ret;
 
-        vmf->cow_page = cow_page;
-
         ret = vma->vm_ops->fault(vma, vmf);
         if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
                 return ret;
-        if (ret & VM_FAULT_DAX_LOCKED) {
-                *entry = vmf->entry;
+        if (ret & VM_FAULT_DAX_LOCKED)
                 return ret;
-        }
 
         if (unlikely(PageHWPoison(vmf->page))) {
                 if (ret & VM_FAULT_LOCKED)
                         unlock_page(vmf->page);
                 put_page(vmf->page);
+                vmf->page = NULL;
                 return VM_FAULT_HWPOISON;
         }
 
@@ -2872,7 +2868,6 @@ static int __do_fault(struct vm_fault *vmf, struct page *cow_page,
         else
                 VM_BUG_ON_PAGE(!PageLocked(vmf->page), vmf->page);
 
-        *page = vmf->page;
         return ret;
 }
 
@@ -3208,7 +3203,6 @@ out:
 static int do_read_fault(struct vm_fault *vmf)
 {
         struct vm_area_struct *vma = vmf->vma;
-        struct page *fault_page;
         int ret = 0;
 
         /*
@@ -3222,54 +3216,52 @@ static int do_read_fault(struct vm_fault *vmf)
                         return ret;
         }
 
-        ret = __do_fault(vmf, NULL, &fault_page, NULL);
+        ret = __do_fault(vmf);
         if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
                 return ret;
 
-        ret |= alloc_set_pte(vmf, NULL, fault_page);
+        ret |= alloc_set_pte(vmf, NULL, vmf->page);
         if (vmf->pte)
                 pte_unmap_unlock(vmf->pte, vmf->ptl);
-        unlock_page(fault_page);
+        unlock_page(vmf->page);
         if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
-                put_page(fault_page);
+                put_page(vmf->page);
         return ret;
 }
 
 static int do_cow_fault(struct vm_fault *vmf)
 {
         struct vm_area_struct *vma = vmf->vma;
-        struct page *fault_page, *new_page;
-        void *fault_entry;
         struct mem_cgroup *memcg;
         int ret;
 
         if (unlikely(anon_vma_prepare(vma)))
                 return VM_FAULT_OOM;
 
-        new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, vmf->address);
-        if (!new_page)
+        vmf->cow_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, vmf->address);
+        if (!vmf->cow_page)
                 return VM_FAULT_OOM;
 
-        if (mem_cgroup_try_charge(new_page, vma->vm_mm, GFP_KERNEL,
+        if (mem_cgroup_try_charge(vmf->cow_page, vma->vm_mm, GFP_KERNEL,
                                 &memcg, false)) {
-                put_page(new_page);
+                put_page(vmf->cow_page);
                 return VM_FAULT_OOM;
         }
 
-        ret = __do_fault(vmf, new_page, &fault_page, &fault_entry);
+        ret = __do_fault(vmf);
         if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
                 goto uncharge_out;
 
         if (!(ret & VM_FAULT_DAX_LOCKED))
-                copy_user_highpage(new_page, fault_page, vmf->address, vma);
-        __SetPageUptodate(new_page);
+                copy_user_highpage(vmf->cow_page, vmf->page, vmf->address, vma);
+        __SetPageUptodate(vmf->cow_page);
 
-        ret |= alloc_set_pte(vmf, memcg, new_page);
+        ret |= alloc_set_pte(vmf, memcg, vmf->cow_page);
         if (vmf->pte)
                 pte_unmap_unlock(vmf->pte, vmf->ptl);
         if (!(ret & VM_FAULT_DAX_LOCKED)) {
-                unlock_page(fault_page);
-                put_page(fault_page);
+                unlock_page(vmf->page);
+                put_page(vmf->page);
         } else {
                 dax_unlock_mapping_entry(vma->vm_file->f_mapping, vmf->pgoff);
         }
@@ -3277,20 +3269,19 @@ static int do_cow_fault(struct vm_fault *vmf)
                 goto uncharge_out;
         return ret;
 uncharge_out:
-        mem_cgroup_cancel_charge(new_page, memcg, false);
-        put_page(new_page);
+        mem_cgroup_cancel_charge(vmf->cow_page, memcg, false);
+        put_page(vmf->cow_page);
         return ret;
 }
 
 static int do_shared_fault(struct vm_fault *vmf)
 {
         struct vm_area_struct *vma = vmf->vma;
-        struct page *fault_page;
         struct address_space *mapping;
         int dirtied = 0;
         int ret, tmp;
 
-        ret = __do_fault(vmf, NULL, &fault_page, NULL);
+        ret = __do_fault(vmf);
         if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
                 return ret;
 
@@ -3299,26 +3290,26 @@ static int do_shared_fault(struct vm_fault *vmf)
          * about to become writable
          */
         if (vma->vm_ops->page_mkwrite) {
-                unlock_page(fault_page);
-                tmp = do_page_mkwrite(vma, fault_page, vmf->address);
+                unlock_page(vmf->page);
+                tmp = do_page_mkwrite(vma, vmf->page, vmf->address);
                 if (unlikely(!tmp ||
                                 (tmp & (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))) {
-                        put_page(fault_page);
+                        put_page(vmf->page);
                         return tmp;
                 }
         }
 
-        ret |= alloc_set_pte(vmf, NULL, fault_page);
+        ret |= alloc_set_pte(vmf, NULL, vmf->page);
         if (vmf->pte)
                 pte_unmap_unlock(vmf->pte, vmf->ptl);
         if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE |
                                         VM_FAULT_RETRY))) {
-                unlock_page(fault_page);
-                put_page(fault_page);
+                unlock_page(vmf->page);
+                put_page(vmf->page);
                 return ret;
         }
 
-        if (set_page_dirty(fault_page))
+        if (set_page_dirty(vmf->page))
                 dirtied = 1;
         /*
          * Take a local copy of the address_space - page.mapping may be zeroed
@@ -3326,8 +3317,8 @@ static int do_shared_fault(struct vm_fault *vmf)
          * pinned by vma->vm_file's reference.  We rely on unlock_page()'s
          * release semantics to prevent the compiler from undoing this copying.
          */
-        mapping = page_rmapping(fault_page);
-        unlock_page(fault_page);
+        mapping = page_rmapping(vmf->page);
+        unlock_page(vmf->page);
         if ((dirtied || vma->vm_ops->page_mkwrite) && mapping) {
                 /*
                  * Some device drivers do not set page.mapping but still