[PATCH 7.1 209/271] mm/huge_memory: initialise workingset state before folio split

7.1-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Matt Fleming <[email protected]>

commit aca1f2d5de17e138bc6c4859126b77e516b82541 upstream.

xas_try_split() adds __GFP_ACCOUNT for page-cache xa_nodes, but
__folio_split() leaves the xa_state's xa_lru unset.  That lets a live,
memcg-charged xa_node exist without being linked into the mapping's
shadow_nodes list_lru; when reclaim later walks the list_lru it trips
VM_WARN_ON(!css_is_dying()).

Use mapping_set_update() to install both the workingset update callback
and the shadow_nodes list_lru on the xa_state.

Link: https://lore.kernel.org/[email protected]
Fixes: 58729c04cf10 ("mm/huge_memory: add buddy allocator like (non-uniform) folio_split()")
Signed-off-by: Matt Fleming <[email protected]>
Reported-by: [email protected]
Closes: https://syzkaller.appspot.com/bug?extid=c5b060ce82921a2fd500
Reviewed-by: Zi Yan <[email protected]>
Acked-by: David Hildenbrand (Arm) <[email protected]>
Cc: Baolin Wang <[email protected]>
Cc: Barry Song <[email protected]>
Cc: Dave Chinner <[email protected]>
Cc: Dev Jain <[email protected]>
Cc: Kairui Song <[email protected]>
Cc: Lance Yang <[email protected]>
Cc: Liam Howlett <[email protected]>
Cc: Lorenzo Stoakes <[email protected]>
Cc: Matthew Wilcox (Oracle) <[email protected]>
Cc: Muchun Song <[email protected]>
Cc: Nico Pache <[email protected]>
Cc: Roman Gushchin <[email protected]>
Cc: Ryan Roberts <[email protected]>
Cc: Shakeel Butt <[email protected]>
Cc: <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
 mm/huge_memory.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -4108,7 +4108,7 @@ static int __folio_split(struct folio *f
 		gfp_t gfp;
 
 		mapping = folio->mapping;
-		min_order = mapping_min_folio_order(folio->mapping);
+		min_order = mapping_min_folio_order(mapping);
 		if (new_order < min_order) {
 			ret = -EINVAL;
 			goto out;
@@ -4122,6 +4122,8 @@ static int __folio_split(struct folio *f
 			goto out;
 		}
 
+		mapping_set_update(&xas, mapping);
+
 		if (split_type == SPLIT_TYPE_UNIFORM) {
 			xas_set_order(&xas, folio->index, new_order);
 			xas_split_alloc(&xas, folio, old_order, gfp);