[PATCH 1/3] mm: add mlock_future_check helper

[Davidlohr Bueso]

Both do_brk and do_mmap_pgoff verify that we 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 <davidl...@hp.com>
Cc: Rik van Riel <r...@redhat.com>
Cc: Michel Lespinasse <wal...@google.com>
---
 mm/mmap.c | 45 +++++++++++++++++++++++----------------------
 1 file changed, 23 insertions(+), 22 deletions(-)

diff --git a/mm/mmap.c b/mm/mmap.c
index 9d54851..6a7824d 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -1192,6 +1192,24 @@ 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).
  */
@@ -1253,16 +1271,8 @@ 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);
@@ -2593,18 +2603,9 @@ 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
-- 
1.8.1.4

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