mm: use fallthrough;

Convert the various /* fallthrough */ comments to the pseudo-keyword
fallthrough;

Done via script:
https://lore.kernel.org/lkml/b56602fcf79f849e733e7b521bb0e17895d390fa.1582230379.git.joe@perches.com/

Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Link: http://lkml.kernel.org/r/f62fea5d10eb0ccfc05d87c242a620c261219b66.camel@perches.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/gup.c

@@ -1102,7 +1102,7 @@ retry:
 				goto retry;
 			case -EBUSY:
 				ret = 0;
-				/* FALLTHRU */
+				fallthrough;
 			case -EFAULT:
 			case -ENOMEM:
 			case -EHWPOISON:

mm/hugetlb_cgroup.c

@@ -467,14 +467,14 @@ static int hugetlb_cgroup_read_u64_max(struct seq_file *seq, void *v)
 	switch (MEMFILE_ATTR(cft->private)) {
 	case RES_RSVD_USAGE:
 		counter = &h_cg->rsvd_hugepage[idx];
-		/* Fall through. */
+		fallthrough;
 	case RES_USAGE:
 		val = (u64)page_counter_read(counter);
 		seq_printf(seq, "%llu\n", val * PAGE_SIZE);
 		break;
 	case RES_RSVD_LIMIT:
 		counter = &h_cg->rsvd_hugepage[idx];
-		/* Fall through. */
+		fallthrough;
 	case RES_LIMIT:
 		val = (u64)counter->max;
 		if (val == limit)
@@ -514,7 +514,7 @@ static ssize_t hugetlb_cgroup_write(struct kernfs_open_file *of,
 	switch (MEMFILE_ATTR(of_cft(of)->private)) {
 	case RES_RSVD_LIMIT:
 		rsvd = true;
-		/* Fall through. */
+		fallthrough;
 	case RES_LIMIT:
 		mutex_lock(&hugetlb_limit_mutex);
 		ret = page_counter_set_max(

mm/ksm.c

@@ -2813,8 +2813,7 @@ static int ksm_memory_callback(struct notifier_block *self,
 		 */
 		ksm_check_stable_tree(mn->start_pfn,
 				      mn->start_pfn + mn->nr_pages);
-		/* fallthrough */
-
+		fallthrough;
 	case MEM_CANCEL_OFFLINE:
 		mutex_lock(&ksm_thread_mutex);
 		ksm_run &= ~KSM_RUN_OFFLINE;

mm/list_lru.c

@@ -223,7 +223,7 @@ restart:
 		switch (ret) {
 		case LRU_REMOVED_RETRY:
 			assert_spin_locked(&nlru->lock);
-			/* fall through */
+			fallthrough;
 		case LRU_REMOVED:
 			isolated++;
 			nlru->nr_items--;

mm/memcontrol.c

@@ -5813,7 +5813,7 @@ retry:
 		switch (get_mctgt_type(vma, addr, ptent, &target)) {
 		case MC_TARGET_DEVICE:
 			device = true;
-			/* fall through */
+			fallthrough;
 		case MC_TARGET_PAGE:
 			page = target.page;
 			/*

mm/mempolicy.c

@@ -881,7 +881,6 @@ static void get_policy_nodemask(struct mempolicy *p, nodemask_t *nodes)
 
 	switch (p->mode) {
 	case MPOL_BIND:
-		/* Fall through */
 	case MPOL_INTERLEAVE:
 		*nodes = p->v.nodes;
 		break;
@@ -2066,7 +2065,6 @@ bool init_nodemask_of_mempolicy(nodemask_t *mask)
 		break;
 
 	case MPOL_BIND:
-		/* Fall through */
 	case MPOL_INTERLEAVE:
 		*mask =  mempolicy->v.nodes;
 		break;
@@ -2333,7 +2331,6 @@ bool __mpol_equal(struct mempolicy *a, struct mempolicy *b)
 
 	switch (a->mode) {
 	case MPOL_BIND:
-		/* Fall through */
 	case MPOL_INTERLEAVE:
 		return !!nodes_equal(a->v.nodes, b->v.nodes);
 	case MPOL_PREFERRED:

mm/mmap.c

@@ -1460,7 +1460,7 @@ unsigned long do_mmap(struct file *file, unsigned long addr,
 			 * with MAP_SHARED to preserve backward compatibility.
 			 */
 			flags &= LEGACY_MAP_MASK;
-			/* fall through */
+			fallthrough;
 		case MAP_SHARED_VALIDATE:
 			if (flags & ~flags_mask)
 				return -EOPNOTSUPP;
@@ -1487,8 +1487,7 @@ unsigned long do_mmap(struct file *file, unsigned long addr,
 			vm_flags |= VM_SHARED | VM_MAYSHARE;
 			if (!(file->f_mode & FMODE_WRITE))
 				vm_flags &= ~(VM_MAYWRITE | VM_SHARED);
-
-			/* fall through */
+			fallthrough;
 		case MAP_PRIVATE:
 			if (!(file->f_mode & FMODE_READ))
 				return -EACCES;

mm/shmem.c

@@ -3996,7 +3996,7 @@ bool shmem_huge_enabled(struct vm_area_struct *vma)
 			if (i_size >= HPAGE_PMD_SIZE &&
 					i_size >> PAGE_SHIFT >= off)
 				return true;
-			/* fall through */
+			fallthrough;
 		case SHMEM_HUGE_ADVISE:
 			/* TODO: implement fadvise() hints */
 			return (vma->vm_flags & VM_HUGEPAGE);

mm/zsmalloc.c

@@ -424,7 +424,7 @@ static void *zs_zpool_map(void *pool, unsigned long handle,
 	case ZPOOL_MM_WO:
 		zs_mm = ZS_MM_WO;
 		break;
-	case ZPOOL_MM_RW: /* fall through */
+	case ZPOOL_MM_RW:
 	default:
 		zs_mm = ZS_MM_RW;
 		break;