[PATCH v4 6/7] Remove zap_details NULL dependency

[Minchan Kim]

Some functions used zap_details depends on assumption that
zap_details parameter should be NULLed if some fields are 0.

This patch removes that dependency for next patch easy review/merge.
It should not chanage behavior.

Signed-off-by: Minchan Kim <minchan.kim@xxxxxxxxx>
Cc: Rik van Riel <riel@xxxxxxxxxx>
Cc: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Nick Piggin <npiggin@xxxxxxxxx>
Cc: Mel Gorman <mel@xxxxxxxxx>
Cc: Wu Fengguang <fengguang.wu@xxxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
---
 include/linux/mm.h |    8 ++++++++
 mm/madvise.c       |   15 +++++++++------
 mm/memory.c        |   14 ++++++++------
 mm/mmap.c          |    6 ++++--
 4 files changed, 29 insertions(+), 14 deletions(-)

diff --git a/include/linux/mm.h b/include/linux/mm.h
index e097df6..6522ae4 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -773,6 +773,14 @@ struct zap_details {
 	unsigned long truncate_count;		/* Compare vm_truncate_count */
 };
 
+#define __ZAP_DETAILS_INITIALIZER(name) \
+		{ .nonlinear_vma = NULL \
+		, .check_mapping = NULL \
+		, .i_mmap_lock = NULL }
+
+#define DEFINE_ZAP_DETAILS(name)		\
+	struct zap_details name = __ZAP_DETAILS_INITIALIZER(name)
+
 struct page *vm_normal_page(struct vm_area_struct *vma, unsigned long addr,
 		pte_t pte);
 
diff --git a/mm/madvise.c b/mm/madvise.c
index 319528b..bfa17aa 100644
--- a/mm/madvise.c
+++ b/mm/madvise.c
@@ -162,18 +162,21 @@ static long madvise_dontneed(struct vm_area_struct * vma,
 			     struct vm_area_struct ** prev,
 			     unsigned long start, unsigned long end)
 {
+	DEFINE_ZAP_DETAILS(details);
+
 	*prev = vma;
 	if (vma->vm_flags & (VM_LOCKED|VM_HUGETLB|VM_PFNMAP))
 		return -EINVAL;
 
 	if (unlikely(vma->vm_flags & VM_NONLINEAR)) {
-		struct zap_details details = {
-			.nonlinear_vma = vma,
-			.last_index = ULONG_MAX,
-		};
+		details.nonlinear_vma = vma;
+		details.last_index = ULONG_MAX;
+
 		zap_page_range(vma, start, end - start, &details);
-	} else
-		zap_page_range(vma, start, end - start, NULL);
+	} else {
+
+		zap_page_range(vma, start, end - start, &details);
+	}
 	return 0;
 }
 
diff --git a/mm/memory.c b/mm/memory.c
index ebfeedf..c0879bb 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -900,6 +900,9 @@ static unsigned long zap_pte_range(struct mmu_gather *tlb,
 
 	init_rss_vec(rss);
 
+	if (!details->check_mapping && !details->nonlinear_vma)
+		details = NULL;
+
 	pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
 	arch_enter_lazy_mmu_mode();
 	do {
@@ -1038,9 +1041,6 @@ static unsigned long unmap_page_range(struct mmu_gather *tlb,
 	pgd_t *pgd;
 	unsigned long next;
 
-	if (details && !details->check_mapping && !details->nonlinear_vma)
-		details = NULL;
-
 	BUG_ON(addr >= end);
 	mem_cgroup_uncharge_start();
 	tlb_start_vma(tlb, vma);
@@ -1102,7 +1102,7 @@ unsigned long unmap_vmas(struct mmu_gather **tlbp,
 	unsigned long tlb_start = 0;	/* For tlb_finish_mmu */
 	int tlb_start_valid = 0;
 	unsigned long start = start_addr;
-	spinlock_t *i_mmap_lock = details? details->i_mmap_lock: NULL;
+	spinlock_t *i_mmap_lock = details->i_mmap_lock;
 	int fullmm = (*tlbp)->fullmm;
 	struct mm_struct *mm = vma->vm_mm;
 
@@ -1217,10 +1217,11 @@ unsigned long zap_page_range(struct vm_area_struct *vma, unsigned long address,
 int zap_vma_ptes(struct vm_area_struct *vma, unsigned long address,
 		unsigned long size)
 {
+	DEFINE_ZAP_DETAILS(details);
 	if (address < vma->vm_start || address + size > vma->vm_end ||
 	    		!(vma->vm_flags & VM_PFNMAP))
 		return -1;
-	zap_page_range(vma, address, size, NULL);
+	zap_page_range(vma, address, size, &details);
 	return 0;
 }
 EXPORT_SYMBOL_GPL(zap_vma_ptes);
@@ -2577,7 +2578,8 @@ restart:
 void unmap_mapping_range(struct address_space *mapping,
 		loff_t const holebegin, loff_t const holelen, int even_cows)
 {
-	struct zap_details details;
+	DEFINE_ZAP_DETAILS(details);
+
 	pgoff_t hba = holebegin >> PAGE_SHIFT;
 	pgoff_t hlen = (holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
 
diff --git a/mm/mmap.c b/mm/mmap.c
index b179abb..31d2594 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -1900,11 +1900,12 @@ static void unmap_region(struct mm_struct *mm,
 	struct vm_area_struct *next = prev? prev->vm_next: mm->mmap;
 	struct mmu_gather *tlb;
 	unsigned long nr_accounted = 0;
+	DEFINE_ZAP_DETAILS(details);
 
 	lru_add_drain();
 	tlb = tlb_gather_mmu(mm, 0);
 	update_hiwater_rss(mm);
-	unmap_vmas(&tlb, vma, start, end, &nr_accounted, NULL);
+	unmap_vmas(&tlb, vma, start, end, &nr_accounted, &details);
 	vm_unacct_memory(nr_accounted);
 	free_pgtables(tlb, vma, prev? prev->vm_end: FIRST_USER_ADDRESS,
 				 next? next->vm_start: 0);
@@ -2254,6 +2255,7 @@ void exit_mmap(struct mm_struct *mm)
 	struct vm_area_struct *vma;
 	unsigned long nr_accounted = 0;
 	unsigned long end;
+	DEFINE_ZAP_DETAILS(details);
 
 	/* mm's last user has gone, and its about to be pulled down */
 	mmu_notifier_release(mm);
@@ -2278,7 +2280,7 @@ void exit_mmap(struct mm_struct *mm)
 	tlb = tlb_gather_mmu(mm, 1);
 	/* update_hiwater_rss(mm) here? but nobody should be looking */
 	/* Use -1 here to ensure all VMAs in the mm are unmapped */
-	end = unmap_vmas(&tlb, vma, 0, -1, &nr_accounted, NULL);
+	end = unmap_vmas(&tlb, vma, 0, -1, &nr_accounted, &details);
 	vm_unacct_memory(nr_accounted);
 
 	free_pgtables(tlb, vma, FIRST_USER_ADDRESS, 0);
-- 
1.7.0.4

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