mm: fix some broken comments

Fix some broken comments including typo, grammar error and wrong function
name.
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Link: https://lkml.kernel.org/r/20200913095456.54873-1-linmiaohe@huawei.comSigned-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/filemap.c

@@ -1445,7 +1445,7 @@ static inline bool clear_bit_unlock_is_negative_byte(long nr, volatile void *mem
  * unlock_page - unlock a locked page
  * @page: the page
  *
- * Unlocks the page and wakes up sleepers in ___wait_on_page_locked().
+ * Unlocks the page and wakes up sleepers in wait_on_page_locked().
  * Also wakes sleepers in wait_on_page_writeback() because the wakeup
  * mechanism between PageLocked pages and PageWriteback pages is shared.
  * But that's OK - sleepers in wait_on_page_writeback() just go back to sleep.
@@ -3004,7 +3004,7 @@ static struct page *do_read_cache_page(struct address_space *mapping,
 		goto out;
 
 	/*
-	 * Page is not up to date and may be locked due one of the following
+	 * Page is not up to date and may be locked due to one of the following
 	 * case a: Page is being filled and the page lock is held
 	 * case b: Read/write error clearing the page uptodate status
 	 * case c: Truncation in progress (page locked)

mm/swap_state.c

@@ -246,7 +246,7 @@ int add_to_swap(struct page *page)
 		goto fail;
 	/*
 	 * Normally the page will be dirtied in unmap because its pte should be
-	 * dirty. A special case is MADV_FREE page. The page'e pte could have
+	 * dirty. A special case is MADV_FREE page. The page's pte could have
 	 * dirty bit cleared but the page's SwapBacked bit is still set because
 	 * clearing the dirty bit and SwapBacked bit has no lock protected. For
 	 * such page, unmap will not set dirty bit for it, so page reclaim will