linux-kernel - [PATCH 2/2] mm, THP: Clean up return value of madvise_free_huge

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Date:	Tue, 28 Jun 2016 10:36:30 -0700
From:	"Huang, Ying" <ying.huang@...el.com>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Huang Ying <ying.huang@...el.com>,
	Minchan Kim <minchan@...nel.org>,
	"Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
	Jerome Marchand <jmarchan@...hat.com>,
	Matthew Wilcox <willy@...ux.intel.com>,
	Vlastimil Babka <vbabka@...e.cz>,
	Dan Williams <dan.j.williams@...el.com>,
	Mel Gorman <mgorman@...hsingularity.net>,
	Andrea Arcangeli <aarcange@...hat.com>,
	Ebru Akagunduz <ebru.akagunduz@...il.com>,
	linux-kernel@...r.kernel.org, linux-mm@...ck.org
Subject: [PATCH 2/2] mm, THP: Clean up return value of madvise_free_huge_pmd

From: Huang Ying <ying.huang@...el.com>

The definition of return value of madvise_free_huge_pmd is not clear
before.  According to the suggestion of Minchan Kim, change the type of
return value to bool and return true if we do MADV_FREE successfully on
entire pmd page, otherwise, return false.  Comments are added too.

Cc: Minchan Kim <minchan@...nel.org>
Signed-off-by: "Huang, Ying" <ying.huang@...el.com>
---
 include/linux/huge_mm.h |  2 +-
 mm/huge_memory.c        | 15 ++++++++-------
 2 files changed, 9 insertions(+), 8 deletions(-)

diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
index eb81081..db97784 100644
--- a/include/linux/huge_mm.h
+++ b/include/linux/huge_mm.h
@@ -11,7 +11,7 @@ extern struct page *follow_trans_huge_pmd(struct vm_area_struct *vma,
 					  unsigned long addr,
 					  pmd_t *pmd,
 					  unsigned int flags);
-extern int madvise_free_huge_pmd(struct mmu_gather *tlb,
+extern bool madvise_free_huge_pmd(struct mmu_gather *tlb,
 			struct vm_area_struct *vma,
 			pmd_t *pmd, unsigned long addr, unsigned long next);
 extern int zap_huge_pmd(struct mmu_gather *tlb,
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 546cd21..d2a5224 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1249,25 +1249,26 @@ out:
 	return 0;
 }
 
-int madvise_free_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
+/*
+ * Return true if we do MADV_FREE successfully on entire pmd page.
+ * Otherwise, return false.
+ */
+bool madvise_free_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
 		pmd_t *pmd, unsigned long addr, unsigned long next)
-
 {
 	spinlock_t *ptl;
 	pmd_t orig_pmd;
 	struct page *page;
 	struct mm_struct *mm = tlb->mm;
-	int ret = 0;
+	bool ret = false;
 
 	ptl = pmd_trans_huge_lock(pmd, vma);
 	if (!ptl)
 		goto out_unlocked;
 
 	orig_pmd = *pmd;
-	if (is_huge_zero_pmd(orig_pmd)) {
-		ret = 1;
+	if (is_huge_zero_pmd(orig_pmd))
 		goto out;
-	}
 
 	page = pmd_page(orig_pmd);
 	/*
@@ -1309,7 +1310,7 @@ int madvise_free_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
 		set_pmd_at(mm, addr, pmd, orig_pmd);
 		tlb_remove_pmd_tlb_entry(tlb, pmd, addr);
 	}
-	ret = 1;
+	ret = true;
 out:
 	spin_unlock(ptl);
 out_unlocked:
-- 
2.8.1