hugetlbfs: do not call user_shm_lock() for MAP_HUGETLB fix

Commit 6bfde05bf5c ("hugetlbfs: allow the creation of files suitable for
MAP_PRIVATE on the vfs internal mount") altered can_do_hugetlb_shm() to
check if a file is being created for shared memory or mmap().  If this
returns false, we then unconditionally call user_shm_lock() triggering a
warning.  This block should never be entered for MAP_HUGETLB.  This
patch partially reverts the problem and fixes the check.

Signed-off-by: Eric B Munson <ebmunson@us.ibm.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Adam Litke <agl@us.ibm.com>
Cc: David Gibson <david@gibson.dropbear.id.au>
Cc: Lee Schermerhorn <lee.schermerhorn@hp.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Hugh Dickins <hugh.dickins@tiscali.co.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 3 insertions, 9 deletions

diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c
index eba6d552d9c9..133335479c24 100644
--- a/fs/hugetlbfs/inode.c
+++ b/fs/hugetlbfs/inode.c
@@ -936,15 +936,9 @@ static struct file_system_type hugetlbfs_fs_type = {
 
 static struct vfsmount *hugetlbfs_vfsmount;
 
-static int can_do_hugetlb_shm(int creat_flags)
+static int can_do_hugetlb_shm(void)
 {
-        if (creat_flags != HUGETLB_SHMFS_INODE)
-                return 0;
-        if (capable(CAP_IPC_LOCK))
-                return 1;
-        if (in_group_p(sysctl_hugetlb_shm_group))
-                return 1;
-        return 0;
+        return capable(CAP_IPC_LOCK) || in_group_p(sysctl_hugetlb_shm_group);
 }
 
 struct file *hugetlb_file_setup(const char *name, size_t size, int acctflag,
@@ -960,7 +954,7 @@ struct file *hugetlb_file_setup(const char *name, size_t size, int acctflag,
         if (!hugetlbfs_vfsmount)
                 return ERR_PTR(-ENOENT);
 
-        if (!can_do_hugetlb_shm(creat_flags)) {
+        if (creat_flags == HUGETLB_SHMFS_INODE && !can_do_hugetlb_shm()) {
                 *user = current_user();
                 if (user_shm_lock(size, *user)) {
                         WARN_ONCE(1,