From: Matthew Wilcox (Oracle) willy@infradead.org
commit 3ed4bb77156da0bc732847c8c9df92454c1fbeea upstream.
When splitting a value entry, we may need to add the new nodes to the LRU list and remove the parent node from the LRU list. The WARN_ON checks in shadow_lru_isolate() catch this oversight. This bug was latent until we stopped splitting folios in shrink_page_list() with commit 820c4e2e6f51 ("mm/vmscan: Free non-shmem folios without splitting them"). That allows the creation of large shadow entries, and subsequently when trying to page in a small page, we will split the large shadow entry in __filemap_add_folio().
Fixes: 8fc75643c5e1 ("XArray: add xas_split") Reported-by: Hugh Dickins hughd@google.com Signed-off-by: Matthew Wilcox (Oracle) willy@infradead.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- lib/xarray.c | 2 ++ 1 file changed, 2 insertions(+)
--- a/lib/xarray.c +++ b/lib/xarray.c @@ -1080,6 +1080,7 @@ void xas_split(struct xa_state *xas, voi xa_mk_node(child)); if (xa_is_value(curr)) values--; + xas_update(xas, child); } else { unsigned int canon = offset - xas->xa_sibs;
@@ -1094,6 +1095,7 @@ void xas_split(struct xa_state *xas, voi } while (offset-- > xas->xa_offset);
node->nr_values += values; + xas_update(xas, node); } EXPORT_SYMBOL_GPL(xas_split); #endif