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Message-ID: <20150701230314.GA18043@redhat.com>
Date: Thu, 2 Jul 2015 01:03:14 +0200
From: Oleg Nesterov <oleg@...hat.com>
To: Andrew Morton <akpm@...ux-foundation.org>
Cc: Benjamin LaHaise <bcrl@...ck.org>,
David Rientjes <rientjes@...gle.com>,
Hugh Dickins <hughd@...gle.com>,
Jeff Moyer <jmoyer@...hat.com>,
Kirill Shutemov <kirill.shutemov@...ux.intel.com>,
Pavel Emelyanov <xemul@...allels.com>,
linux-kernel@...r.kernel.org
Subject: [PATCH v2 5/5] mremap: simplify the "overlap" check in mremap_to()
Minor, but this check is overcomplicated. Two half-intervals do NOT
overlap if END1 <= START2 || END2 <= START1, mremap_to() just needs
to negate this check.
Signed-off-by: Oleg Nesterov <oleg@...hat.com>
Acked-by: David Rientjes <rientjes@...gle.com>
---
mm/mremap.c | 9 ++-------
1 files changed, 2 insertions(+), 7 deletions(-)
diff --git a/mm/mremap.c b/mm/mremap.c
index d3f42be..5a71cce 100644
--- a/mm/mremap.c
+++ b/mm/mremap.c
@@ -407,13 +407,8 @@ static unsigned long mremap_to(unsigned long addr, unsigned long old_len,
if (new_len > TASK_SIZE || new_addr > TASK_SIZE - new_len)
goto out;
- /* Check if the location we're moving into overlaps the
- * old location at all, and fail if it does.
- */
- if ((new_addr <= addr) && (new_addr+new_len) > addr)
- goto out;
-
- if ((addr <= new_addr) && (addr+old_len) > new_addr)
+ /* Ensure the old/new locations do not overlap */
+ if (addr + old_len > new_addr && new_addr + new_len > addr)
goto out;
ret = do_munmap(mm, new_addr, new_len);
--
1.5.5.1
--
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