linux-kernel - [PATCH 3/3] mm/swapfile.c: count won't be bigger than SWAP_MAP

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Message-Id: <20200501015259.32237-3-richard.weiyang@gmail.com>
Date:   Fri,  1 May 2020 01:52:59 +0000
From:   Wei Yang <richard.weiyang@...il.com>
To:     akpm@...ux-foundation.org, ying.huang@...el.com
Cc:     linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        Wei Yang <richard.weiyang@...il.com>
Subject: [PATCH 3/3] mm/swapfile.c: count won't be bigger than SWAP_MAP_MAX

When the condition is true, there are two possibilities:

   1. count == SWAP_MAP_BAD
   2. count == (SWAP_MAP_MAX & COUNT_CONTINUED) == SWAP_MAP_SHMEM

The first case would be filtered by the first if in __swap_duplicate().

And the second case means this swap entry is for shmem. Since we never
do another duplication for shmem swap entry. This won't happen neither.

Signed-off-by: Wei Yang <richard.weiyang@...il.com>
---
 mm/swapfile.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/mm/swapfile.c b/mm/swapfile.c
index 1a877d1d40e3..88dd2ad34aad 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -3404,8 +3404,6 @@ static int __swap_duplicate(swp_entry_t entry, unsigned char usage)
 
 		if ((count & ~COUNT_CONTINUED) < SWAP_MAP_MAX)
 			count += usage;
-		else if ((count & ~COUNT_CONTINUED) > SWAP_MAP_MAX)
-			err = -EINVAL;
 		else if (swap_count_continued(p, offset, count))
 			count = COUNT_CONTINUED;
 		else
-- 
2.23.0