mm: create new codetag references during page splitting

When a high-order page is split into smaller ones, each newly split page
should get its codetag.  After the split each split page will be
referencing the original codetag.  The codetag's "bytes" counter remains
the same because the amount of allocated memory has not changed, however
the "calls" counter gets increased to keep the counter correct when these
individual pages get freed.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Suren Baghdasaryan <[email protected]>
Reviewed-by: Vlastimil Babka <[email protected]>
Tested-by: Kees Cook <[email protected]>
Cc: Alexander Viro <[email protected]>
Cc: Alex Gaynor <[email protected]>
Cc: Alice Ryhl <[email protected]>
Cc: Andreas Hindborg <[email protected]>
Cc: Benno Lossin <[email protected]>
Cc: "Björn Roy Baron" <[email protected]>
Cc: Boqun Feng <[email protected]>
Cc: Christoph Lameter <[email protected]>
Cc: Dennis Zhou <[email protected]>
Cc: Gary Guo <[email protected]>
Cc: Kent Overstreet <[email protected]>
Cc: Miguel Ojeda <[email protected]>
Cc: Pasha Tatashin <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Tejun Heo <[email protected]>
Cc: Wedson Almeida Filho <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

1 files changed, 2 insertions, 0 deletions

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index d3afaf8f983a..e453ee22d489 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -2630,6 +2630,7 @@ void split_page(struct page *page, unsigned int order)
 	for (i = 1; i < (1 << order); i++)
 		set_page_refcounted(page + i);
 	split_page_owner(page, order, 0);
+	pgalloc_tag_split(page, 1 << order);
 	split_page_memcg(page, order, 0);
 }
 EXPORT_SYMBOL_GPL(split_page);
@@ -4827,6 +4828,7 @@ static void *make_alloc_exact(unsigned long addr, unsigned int order,
 		struct page *last = page + nr;
 
 		split_page_owner(page, order, 0);
+		pgalloc_tag_split(page, 1 << order);
 		split_page_memcg(page, order, 0);
 		while (page < --last)
 			set_page_refcounted(last);