From: Miaohe Lin <linmiaohe@huawei.com>
To: <akpm@linux-foundation.org>
Cc: <linux-mm@kvack.org>, <linux-kernel@vger.kernel.org>,
<linmiaohe@huawei.com>
Subject: [PATCH] mm/mremap: avoid unneeded do_munmap call
Date: Fri, 1 Apr 2022 16:10:23 +0800 [thread overview]
Message-ID: <20220401081023.37080-1-linmiaohe@huawei.com> (raw)
When old_len == new_len, do_munmap will return -EINVAL due to len == 0.
This errno will be simply ignored because of old_len != new_len check.
So it is unnecessary to call do_munmap when old_len == new_len because
nothing is actually done.
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
---
mm/mremap.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/mm/mremap.c b/mm/mremap.c
index e776d4c2345c..dd966621a056 100644
--- a/mm/mremap.c
+++ b/mm/mremap.c
@@ -817,9 +817,9 @@ static unsigned long mremap_to(unsigned long addr, unsigned long old_len,
goto out;
}
- if (old_len >= new_len) {
+ if (old_len > new_len) {
ret = do_munmap(mm, addr+new_len, old_len - new_len, uf_unmap);
- if (ret && old_len != new_len)
+ if (ret)
goto out;
old_len = new_len;
}
--
2.23.0
next reply other threads:[~2022-04-01 8:10 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-04-01 8:10 Miaohe Lin [this message]
2022-04-01 10:38 ` David Hildenbrand
2022-04-02 1:52 ` Miaohe Lin
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