mm: introduce __GFP_NO_OBJ_EXT flag to selectively prevent slabobj_ext creation

Introduce __GFP_NO_OBJ_EXT flag in order to prevent recursive allocations
when allocating slabobj_ext on a slab.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Suren Baghdasaryan <[email protected]>
Reviewed-by: Kees Cook <[email protected]>
Reviewed-by: Pasha Tatashin <[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: 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, 11 insertions, 0 deletions

diff --git a/include/linux/gfp_types.h b/include/linux/gfp_types.h
index 13becafe41df..313be4ad79fd 100644
--- a/include/linux/gfp_types.h
+++ b/include/linux/gfp_types.h
@@ -55,6 +55,9 @@ enum {
 #ifdef CONFIG_LOCKDEP
 	___GFP_NOLOCKDEP_BIT,
 #endif
+#ifdef CONFIG_SLAB_OBJ_EXT
+	___GFP_NO_OBJ_EXT_BIT,
+#endif
 	___GFP_LAST_BIT
 };
 
@@ -95,6 +98,11 @@ enum {
 #else
 #define ___GFP_NOLOCKDEP	0
 #endif
+#ifdef CONFIG_SLAB_OBJ_EXT
+#define ___GFP_NO_OBJ_EXT       BIT(___GFP_NO_OBJ_EXT_BIT)
+#else
+#define ___GFP_NO_OBJ_EXT       0
+#endif
 
 /*
  * Physical address zone modifiers (see linux/mmzone.h - low four bits)
@@ -135,12 +143,15 @@ enum {
  * node with no fallbacks or placement policy enforcements.
  *
  * %__GFP_ACCOUNT causes the allocation to be accounted to kmemcg.
+ *
+ * %__GFP_NO_OBJ_EXT causes slab allocation to have no object extension.
  */
 #define __GFP_RECLAIMABLE ((__force gfp_t)___GFP_RECLAIMABLE)
 #define __GFP_WRITE	((__force gfp_t)___GFP_WRITE)
 #define __GFP_HARDWALL   ((__force gfp_t)___GFP_HARDWALL)
 #define __GFP_THISNODE	((__force gfp_t)___GFP_THISNODE)
 #define __GFP_ACCOUNT	((__force gfp_t)___GFP_ACCOUNT)
+#define __GFP_NO_OBJ_EXT   ((__force gfp_t)___GFP_NO_OBJ_EXT)
 
 /**
  * DOC: Watermark modifiers