mm/mmap.c: add mlock_future_check() helper

Both do_brk and do_mmap_pgoff verify that we are actually capable of
locking future pages if the corresponding VM_LOCKED flags are used.
Encapsulate this logic into a single mlock_future_check() helper
function.

Signed-off-by: Davidlohr Bueso <davidlohr@hp.com>
Cc: Rik van Riel <riel@redhat.com>
Reviewed-by: Michel Lespinasse <walken@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 23 insertions, 22 deletions

diff --git a/mm/mmap.c b/mm/mmap.c
index 39552de6e1db..a0e7153a79e6 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -1191,6 +1191,24 @@ static inline unsigned long round_hint_to_min(unsigned long hint)
         return hint;
 }
 
+static inline int mlock_future_check(struct mm_struct *mm,
+                                     unsigned long flags,
+                                     unsigned long len)
+{
+        unsigned long locked, lock_limit;
+
+        /*  mlock MCL_FUTURE? */
+        if (flags & VM_LOCKED) {
+                locked = len >> PAGE_SHIFT;
+                locked += mm->locked_vm;
+                lock_limit = rlimit(RLIMIT_MEMLOCK);
+                lock_limit >>= PAGE_SHIFT;
+                if (locked > lock_limit && !capable(CAP_IPC_LOCK))
+                        return -EAGAIN;
+        }
+        return 0;
+}
+
 /*
  * The caller must hold down_write(&current->mm->mmap_sem).
  */
@@ -1252,16 +1270,8 @@ unsigned long do_mmap_pgoff(struct file *file, unsigned long addr,
                 if (!can_do_mlock())
                         return -EPERM;
 
-        /* mlock MCL_FUTURE? */
-        if (vm_flags & VM_LOCKED) {
-                unsigned long locked, lock_limit;
-                locked = len >> PAGE_SHIFT;
-                locked += mm->locked_vm;
-                lock_limit = rlimit(RLIMIT_MEMLOCK);
-                lock_limit >>= PAGE_SHIFT;
-                if (locked > lock_limit && !capable(CAP_IPC_LOCK))
-                        return -EAGAIN;
-        }
+        if (mlock_future_check(mm, vm_flags, len))
+                return -EAGAIN;
 
         if (file) {
                 struct inode *inode = file_inode(file);
@@ -2592,18 +2602,9 @@ static unsigned long do_brk(unsigned long addr, unsigned long len)
         if (error & ~PAGE_MASK)
                 return error;
 
-        /*
-         * mlock MCL_FUTURE?
-         */
-        if (mm->def_flags & VM_LOCKED) {
-                unsigned long locked, lock_limit;
-                locked = len >> PAGE_SHIFT;
-                locked += mm->locked_vm;
-                lock_limit = rlimit(RLIMIT_MEMLOCK);
-                lock_limit >>= PAGE_SHIFT;
-                if (locked > lock_limit && !capable(CAP_IPC_LOCK))
-                        return -EAGAIN;
-        }
+        error = mlock_future_check(mm, mm->def_flags, len);
+        if (error)
+                return error;
 
         /*
          * mm->mmap_sem is required to protect against another thread