linux-kernel - [PATCH 4.9 38/84] mm, shmem: fix handling /sys/kernel/mm/transparent_hugepage/shmem

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Date:   Mon, 28 Aug 2017 10:05:03 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
        Dan Carpenter <dan.carpenter@...cle.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>
Subject: [PATCH 4.9 38/84] mm, shmem: fix handling /sys/kernel/mm/transparent_hugepage/shmem_enabled

4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>

commit 435c0b87d661da83771c30ed775f7c37eed193fb upstream.

/sys/kernel/mm/transparent_hugepage/shmem_enabled controls if we want
to allocate huge pages when allocate pages for private in-kernel shmem
mount.

Unfortunately, as Dan noticed, I've screwed it up and the only way to
make kernel allocate huge page for the mount is to use "force" there.
All other values will be effectively ignored.

Link: http://lkml.kernel.org/r/20170822144254.66431-1-kirill.shutemov@linux.intel.com
Fixes: 5a6e75f8110c ("shmem: prepare huge= mount option and sysfs knob")
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>
Reported-by: Dan Carpenter <dan.carpenter@...cle.com>
Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 mm/shmem.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -3810,7 +3810,7 @@ int __init shmem_init(void)
 	}

 #ifdef CONFIG_TRANSPARENT_HUGE_PAGECACHE
-	if (has_transparent_hugepage() && shmem_huge < SHMEM_HUGE_DENY)
+	if (has_transparent_hugepage() && shmem_huge > SHMEM_HUGE_DENY)
 		SHMEM_SB(shm_mnt->mnt_sb)->huge = shmem_huge;
 	else
 		shmem_huge = 0; /* just in case it was patched */
@@ -3871,7 +3871,7 @@ static ssize_t shmem_enabled_store(struc
 		return -EINVAL;

 	shmem_huge = huge;
-	if (shmem_huge < SHMEM_HUGE_DENY)
+	if (shmem_huge > SHMEM_HUGE_DENY)
 		SHMEM_SB(shm_mnt->mnt_sb)->huge = shmem_huge;
 	return count;
 }