linux-kernel - [PATCH 1/5] mm: MADV

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Date:	Mon, 19 Oct 2015 15:31:43 +0900
From:	Minchan Kim <minchan@...nel.org>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	linux-mm@...ck.org, linux-kernel@...r.kernel.org,
	Hugh Dickins <hughd@...gle.com>,
	Rik van Riel <riel@...hat.com>, Mel Gorman <mgorman@...e.de>,
	Michal Hocko <mhocko@...e.cz>,
	Johannes Weiner <hannes@...xchg.org>,
	"Kirill A. Shutemov" <kirill@...temov.name>,
	Vlastimil Babka <vbabka@...e.cz>,
	Minchan Kim <minchan@...nel.org>
Subject: [PATCH 1/5] mm: MADV_FREE trivial clean up

1. Page table waker already pass the vma it is processing
so we don't need to pass vma.

2. If page table entry is dirty in try_to_unmap_one, the dirtiness
should propagate to PG_dirty of the page. So, it's enough to check
only PageDirty without other pte dirty bit checking.

Signed-off-by: Minchan Kim <minchan@...nel.org>
---
 mm/madvise.c | 17 +++--------------
 mm/rmap.c    |  6 ++----
 2 files changed, 5 insertions(+), 18 deletions(-)

diff --git a/mm/madvise.c b/mm/madvise.c
index 7835bc1eaccb..fdfb14a78c60 100644
--- a/mm/madvise.c
+++ b/mm/madvise.c
@@ -24,11 +24,6 @@
 
 #include <asm/tlb.h>
 
-struct madvise_free_private {
-	struct vm_area_struct *vma;
-	struct mmu_gather *tlb;
-};
-
 /*
  * Any behaviour which results in changes to the vma->vm_flags needs to
  * take mmap_sem for writing. Others, which simply traverse vmas, need
@@ -269,10 +264,9 @@ static int madvise_free_pte_range(pmd_t *pmd, unsigned long addr,
 				unsigned long end, struct mm_walk *walk)
 
 {
-	struct madvise_free_private *fp = walk->private;
-	struct mmu_gather *tlb = fp->tlb;
+	struct mmu_gather *tlb = walk->private;
 	struct mm_struct *mm = tlb->mm;
-	struct vm_area_struct *vma = fp->vma;
+	struct vm_area_struct *vma = walk->vma;
 	spinlock_t *ptl;
 	pte_t *pte, ptent;
 	struct page *page;
@@ -365,15 +359,10 @@ static void madvise_free_page_range(struct mmu_gather *tlb,
 			     struct vm_area_struct *vma,
 			     unsigned long addr, unsigned long end)
 {
-	struct madvise_free_private fp = {
-		.vma = vma,
-		.tlb = tlb,
-	};
-
 	struct mm_walk free_walk = {
 		.pmd_entry = madvise_free_pte_range,
 		.mm = vma->vm_mm,
-		.private = &fp,
+		.private = tlb,
 	};
 
 	BUG_ON(addr >= end);
diff --git a/mm/rmap.c b/mm/rmap.c
index 6f0f9331a20f..94ee372e238b 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -1380,7 +1380,6 @@ static int try_to_unmap_one(struct page *page, struct vm_area_struct *vma,
 	spinlock_t *ptl;
 	int ret = SWAP_AGAIN;
 	enum ttu_flags flags = (enum ttu_flags)arg;
-	int dirty = 0;
 
 	pte = page_check_address(page, mm, address, &ptl, 0);
 	if (!pte)
@@ -1423,8 +1422,7 @@ static int try_to_unmap_one(struct page *page, struct vm_area_struct *vma,
 	}
 
 	/* Move the dirty bit to the physical page now the pte is gone. */
-	dirty = pte_dirty(pteval);
-	if (dirty)
+	if (pte_dirty(pteval))
 		set_page_dirty(page);
 
 	/* Update high watermark before we lower rss */
@@ -1457,7 +1455,7 @@ static int try_to_unmap_one(struct page *page, struct vm_area_struct *vma,
 
 		if (flags & TTU_FREE) {
 			VM_BUG_ON_PAGE(PageSwapCache(page), page);
-			if (!dirty && !PageDirty(page)) {
+			if (!PageDirty(page)) {
 				/* It's a freeable page by MADV_FREE */
 				dec_mm_counter(mm, MM_ANONPAGES);
 				goto discard;
-- 
1.9.1

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