mm, shmem: fix handling /sys/kernel/mm/transparent_hugepage/shmem_enabled

/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>
Cc: stable <stable@vger.kernel.org> [4.8+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/shmem.c b/mm/shmem.c
index 6540e598244412023db650412062604b704b58b3..fbcb3c96a186e8bcf9758189e4d1f17f1bc00cdd 100644 (file)
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -3967,7 +3967,7 @@ 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 */
@@ -4028,7 +4028,7 @@ static ssize_t shmem_enabled_store(struct kobject *kobj,
                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;
 }