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Subject[PATCH 1/3] mm: add mlock_future_check helper
Date
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 <davidlohr@hp.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Michel Lespinasse <walken@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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