linux-kernel - [PATCH 1/2] shmem: fix tmpfs to handle the huge= option properly

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Date:   Fri,  9 Sep 2016 16:24:22 -0600
From:   Toshi Kani <toshi.kani@....com>
To:     akpm@...ux-foundation.org
Cc:     dan.j.williams@...el.com, mawilcox@...rosoft.com, hughd@...gle.com,
        kirill.shutemov@...ux.intel.com, toshi.kani@....com,
        linux-nvdimm@...ts.01.org, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH 1/2] shmem: fix tmpfs to handle the huge= option properly

shmem_get_unmapped_area() checks SHMEM_SB(sb)->huge incorrectly,
which leads to a reversed effect of "huge=" mount option.

Fix the check in shmem_get_unmapped_area().

Note, the default value of SHMEM_SB(sb)->huge remains as
SHMEM_HUGE_NEVER.  User will need to specify "huge=" option to
enable huge page mappings.

Reported-by: Hillf Danton <hillf.zj@...baba-inc.com>
Signed-off-by: Toshi Kani <toshi.kani@....com>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>
Cc: Hugh Dickins <hughd@...gle.com>
---
 mm/shmem.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/shmem.c b/mm/shmem.c
index fd8b2b5..aec5b49 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -1980,7 +1980,7 @@ unsigned long shmem_get_unmapped_area(struct file *file,
 				return addr;
 			sb = shm_mnt->mnt_sb;
 		}
-		if (SHMEM_SB(sb)->huge != SHMEM_HUGE_NEVER)
+		if (SHMEM_SB(sb)->huge == SHMEM_HUGE_NEVER)
 			return addr;
 	}