mm: drop zap_details::check_swap_entries

detail == NULL would give the same functionality as
.check_swap_entries==true.

Link: http://lkml.kernel.org/r/20170118122429.43661-2-kirill.shutemov@linux.intel.com
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

include/linux/mm.h

@@ -1175,7 +1175,6 @@ struct zap_details {
 	struct address_space *check_mapping;	/* Check page->mapping if set */
 	pgoff_t	first_index;			/* Lowest page->index to unmap */
 	pgoff_t last_index;			/* Highest page->index to unmap */
-	bool check_swap_entries;		/* Check also swap entries */
 };
 
 struct page *vm_normal_page(struct vm_area_struct *vma, unsigned long addr,

mm/memory.c

@@ -1173,8 +1173,8 @@ again:
 			}
 			continue;
 		}
-		/* only check swap_entries if explicitly asked for in details */
-		if (unlikely(details && !details->check_swap_entries))
+		/* If details->check_mapping, we leave swap entries. */
+		if (unlikely(details))
 			continue;
 
 		entry = pte_to_swp_entry(ptent);

mm/oom_kill.c

@@ -465,7 +465,6 @@ static bool __oom_reap_task_mm(struct task_struct *tsk, struct mm_struct *mm)
 {
 	struct mmu_gather tlb;
 	struct vm_area_struct *vma;
-	struct zap_details details = {.check_swap_entries = true};
 	bool ret = true;
 
 	/*
@@ -531,7 +530,7 @@ static bool __oom_reap_task_mm(struct task_struct *tsk, struct mm_struct *mm)
 		 */
 		if (vma_is_anonymous(vma) || !(vma->vm_flags & VM_SHARED))
 			unmap_page_range(&tlb, vma, vma->vm_start, vma->vm_end,
-					 &details);
+					 NULL);
 	}
 	tlb_finish_mmu(&tlb, 0, -1);
 	pr_info("oom_reaper: reaped process %d (%s), now anon-rss:%lukB, file-rss:%lukB, shmem-rss:%lukB\n",