diff --git a/mm/readahead.c b/mm/readahead.c
index 50a64d8e06b0..2bc3abf07828 100644
--- a/mm/readahead.c
+++ b/mm/readahead.c
@@ -448,7 +448,8 @@ void page_cache_ra_order(struct readahead_control *ractl,
 		struct file_ra_state *ra, unsigned int new_order)
 {
 	struct address_space *mapping = ractl->mapping;
-	pgoff_t index = readahead_index(ractl);
+	pgoff_t start = readahead_index(ractl);
+	pgoff_t index = start;
 	unsigned int min_order = mapping_min_folio_order(mapping);
 	pgoff_t limit = (i_size_read(mapping->host) - 1) >> PAGE_SHIFT;
 	pgoff_t mark = index + ra->size - ra->async_size;
@@ -506,12 +507,18 @@ void page_cache_ra_order(struct readahead_control *ractl,
 	/*
 	 * If there were already pages in the page cache, then we may have
 	 * left some gaps.  Let the regular readahead code take care of this
-	 * situation.
+	 * situation below.
 	 */
 	if (!err)
 		return;
 fallback:
-	do_page_cache_ra(ractl, ra->size, ra->async_size);
+	/*
+	 * ->readahead() may have updated readahead window size so we have to
+	 * check there's still something to read.
+	 */
+	if (ra->size > index - start)
+		do_page_cache_ra(ractl, ra->size - (index - start),
+				 ra->async_size);
 }
 
 static unsigned long ractl_max_pages(struct readahead_control *ractl,