maple_tree: reduce stack usage with gcc-9 and earlier

gcc-10 changed the way inlining works to be less aggressive, but older
versions run into an oversized stack frame warning whenever
CONFIG_KASAN_STACK is enabled, as that forces variables from inlined
callees to be non-overlapping:

lib/maple_tree.c: In function 'mas_wr_bnode':
lib/maple_tree.c:4320:1: error: the frame size of 1424 bytes is larger than 1024 bytes [-Werror=frame-larger-than=]

Change the annotations on mas_store_b_node() and mas_commit_b_node()
to explicitly forbid inlining in this configuration, which is
the same behavior that newer versions already have.

Link: https://lkml.kernel.org/r/20230214103030.1051950-1-arnd@kernel.org
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: Vernon Yang <vernon2gm@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/lib/maple_tree.c b/lib/maple_tree.c
index 5e9703189259059daa3333b8a44aac40b451f476..646297cae5d16dea90e9fbc0b22d02f2198c6b93 100644 (file)
--- a/lib/maple_tree.c
+++ b/lib/maple_tree.c
@@ -146,6 +146,13 @@ struct maple_subtree_state {
        struct maple_big_node *bn;
 };
 
+#ifdef CONFIG_KASAN_STACK
+/* Prevent mas_wr_bnode() from exceeding the stack frame limit */
+#define noinline_for_kasan noinline_for_stack
+#else
+#define noinline_for_kasan inline
+#endif
+
 /* Functions */
 static inline struct maple_node *mt_alloc_one(gfp_t gfp)
 {
@@ -2107,7 +2114,7 @@ static inline void mas_bulk_rebalance(struct ma_state *mas, unsigned char end,
  *
  * Return: The actual end of the data stored in @b_node
  */
-static inline void mas_store_b_node(struct ma_wr_state *wr_mas,
+static noinline_for_kasan void mas_store_b_node(struct ma_wr_state *wr_mas,
                struct maple_big_node *b_node, unsigned char offset_end)
 {
        unsigned char slot;
@@ -3579,7 +3586,7 @@ static inline bool mas_reuse_node(struct ma_wr_state *wr_mas,
  * @b_node: The maple big node
  * @end: The end of the data.
  */
-static inline int mas_commit_b_node(struct ma_wr_state *wr_mas,
+static noinline_for_kasan int mas_commit_b_node(struct ma_wr_state *wr_mas,
                            struct maple_big_node *b_node, unsigned char end)
 {
        struct maple_node *node;