linux-kernel - [PATCH v2] mm: Unsigned 'nr_pages' always larger than zero

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Message-ID: <1567649871-60594-1-git-send-email-zhongjiang@huawei.com>
Date:   Thu, 5 Sep 2019 10:17:51 +0800
From:   zhong jiang <zhongjiang@...wei.com>
To:     <akpm@...ux-foundation.org>, <vbabka@...e.cz>
CC:     <mhocko@...nel.org>, <zhongjiang@...wei.com>, <linux-mm@...ck.org>,
        <linux-kernel@...r.kernel.org>
Subject: [PATCH v2] mm: Unsigned 'nr_pages' always larger than zero

With the help of unsigned_lesser_than_zero.cocci. Unsigned 'nr_pages'
compare with zero. And __gup_longterm_locked pass an long local variant
'rc' to check_and_migrate_cma_pages. Hence it is nicer to change the
parameter to long to fix the issue.

Fixes: 932f4a630a69 ("mm/gup: replace get_user_pages_longterm() with FOLL_LONGTERM")
Signed-off-by: zhong jiang <zhongjiang@...wei.com>
---
 mm/gup.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/mm/gup.c b/mm/gup.c
index 23a9f9c..ee0b71f 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -1433,13 +1433,13 @@ static struct page *new_non_cma_page(struct page *page, unsigned long private)
 static long check_and_migrate_cma_pages(struct task_struct *tsk,
 					struct mm_struct *mm,
 					unsigned long start,
-					unsigned long nr_pages,
+					long nr_pages,
 					struct page **pages,
 					struct vm_area_struct **vmas,
 					unsigned int gup_flags)
 {
-	unsigned long i;
-	unsigned long step;
+	long i;
+	long step;
 	bool drain_allow = true;
 	bool migrate_allow = true;
 	LIST_HEAD(cma_page_list);
@@ -1520,7 +1520,7 @@ static long check_and_migrate_cma_pages(struct task_struct *tsk,
 static long check_and_migrate_cma_pages(struct task_struct *tsk,
 					struct mm_struct *mm,
 					unsigned long start,
-					unsigned long nr_pages,
+					long nr_pages,
 					struct page **pages,
 					struct vm_area_struct **vmas,
 					unsigned int gup_flags)
-- 
1.7.12.4