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

Greg Kroah-Hartman
2017-08-28T08:11:36Z

From: Kirill A. Shutemov <kirill.shutemov@linux.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@linux.intel.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.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;
}