mm: use mmget_not_zero() helper

We already have the helper, we can convert the rest of the kernel
mechanically using:

  git grep -l 'atomic_inc_not_zero.*mm_users' | xargs sed -i 's/atomic_inc_not_zero(&\(.*\)->mm_users)/mmget_not_zero\(\1\)/'

This is needed for a later patch that hooks into the helper, but might
be a worthwhile cleanup on its own.

Link: http://lkml.kernel.org/r/20161218123229.22952-3-vegard.nossum@oracle.com
Signed-off-by: Vegard Nossum <vegard.nossum@oracle.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/gpu/drm/i915/i915_gem_userptr.c

@@ -507,7 +507,7 @@ __i915_gem_userptr_get_pages_worker(struct work_struct *_work)
 			flags |= FOLL_WRITE;
 
 		ret = -EFAULT;
-		if (atomic_inc_not_zero(&mm->mm_users)) {
+		if (mmget_not_zero(mm)) {
 			down_read(&mm->mmap_sem);
 			while (pinned < npages) {
 				ret = get_user_pages_remote

drivers/iommu/intel-svm.c

@@ -579,7 +579,7 @@ static irqreturn_t prq_event_thread(int irq, void *d)
 		if (!svm->mm)
 			goto bad_req;
 		/* If the mm is already defunct, don't handle faults. */
-		if (!atomic_inc_not_zero(&svm->mm->mm_users))
+		if (!mmget_not_zero(svm->mm))
 			goto bad_req;
 		down_read(&svm->mm->mmap_sem);
 		vma = find_extend_vma(svm->mm, address);

fs/proc/base.c

@@ -813,7 +813,7 @@ static ssize_t mem_rw(struct file *file, char __user *buf,
 		return -ENOMEM;
 
 	copied = 0;
-	if (!atomic_inc_not_zero(&mm->mm_users))
+	if (!mmget_not_zero(mm))
 		goto free;
 
 	/* Maybe we should limit FOLL_FORCE to actual ptrace users? */
@@ -921,7 +921,7 @@ static ssize_t environ_read(struct file *file, char __user *buf,
 		return -ENOMEM;
 
 	ret = 0;
-	if (!atomic_inc_not_zero(&mm->mm_users))
+	if (!mmget_not_zero(mm))
 		goto free;
 
 	down_read(&mm->mmap_sem);

fs/proc/task_mmu.c

@@ -167,7 +167,7 @@ static void *m_start(struct seq_file *m, loff_t *ppos)
 		return ERR_PTR(-ESRCH);
 
 	mm = priv->mm;
-	if (!mm || !atomic_inc_not_zero(&mm->mm_users))
+	if (!mm || !mmget_not_zero(mm))
 		return NULL;
 
 	down_read(&mm->mmap_sem);
@@ -1352,7 +1352,7 @@ static ssize_t pagemap_read(struct file *file, char __user *buf,
 	unsigned long end_vaddr;
 	int ret = 0, copied = 0;
 
-	if (!mm || !atomic_inc_not_zero(&mm->mm_users))
+	if (!mm || !mmget_not_zero(mm))
 		goto out;
 
 	ret = -EINVAL;

fs/proc/task_nommu.c

@@ -219,7 +219,7 @@ static void *m_start(struct seq_file *m, loff_t *pos)
 		return ERR_PTR(-ESRCH);
 
 	mm = priv->mm;
-	if (!mm || !atomic_inc_not_zero(&mm->mm_users))
+	if (!mm || !mmget_not_zero(mm))
 		return NULL;
 
 	down_read(&mm->mmap_sem);

kernel/events/uprobes.c

@@ -747,7 +747,7 @@ build_map_info(struct address_space *mapping, loff_t offset, bool is_register)
 			continue;
 		}
 
-		if (!atomic_inc_not_zero(&vma->vm_mm->mm_users))
+		if (!mmget_not_zero(vma->vm_mm))
 			continue;
 
 		info = prev;

mm/swapfile.c

@@ -1763,7 +1763,7 @@ int try_to_unuse(unsigned int type, bool frontswap,
 			while (swap_count(*swap_map) && !retval &&
 					(p = p->next) != &start_mm->mmlist) {
 				mm = list_entry(p, struct mm_struct, mmlist);
-				if (!atomic_inc_not_zero(&mm->mm_users))
+				if (!mmget_not_zero(mm))
 					continue;
 				spin_unlock(&mmlist_lock);
 				mmput(prev_mm);