linux-kernel - [RFC PATCH 12/30] mm: introduce __GFP_NO_OBJ_EXT flag to selectively prevent slabobj

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Message-ID: <20220830214919.53220-13-surenb@google.com>
Date:   Tue, 30 Aug 2022 14:49:01 -0700
From:   Suren Baghdasaryan <surenb@...gle.com>
To:     akpm@...ux-foundation.org
Cc:     kent.overstreet@...ux.dev, mhocko@...e.com, vbabka@...e.cz,
        hannes@...xchg.org, roman.gushchin@...ux.dev, mgorman@...e.de,
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Subject: [RFC PATCH 12/30] 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.

Signed-off-by: Suren Baghdasaryan <surenb@...gle.com>
---
 include/linux/gfp_types.h | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/include/linux/gfp_types.h b/include/linux/gfp_types.h
index d88c46ca82e1..a2cba1d20b86 100644
--- a/include/linux/gfp_types.h
+++ b/include/linux/gfp_types.h
@@ -55,8 +55,13 @@ typedef unsigned int __bitwise gfp_t;
 #define ___GFP_SKIP_KASAN_UNPOISON	0
 #define ___GFP_SKIP_KASAN_POISON	0
 #endif
+#ifdef CONFIG_SLAB_OBJ_EXT
+#define ___GFP_NO_OBJ_EXT       0x8000000u
+#else
+#define ___GFP_NO_OBJ_EXT       0
+#endif
 #ifdef CONFIG_LOCKDEP
-#define ___GFP_NOLOCKDEP	0x8000000u
+#define ___GFP_NOLOCKDEP	0x10000000u
 #else
 #define ___GFP_NOLOCKDEP	0
 #endif
@@ -101,12 +106,15 @@ typedef unsigned int __bitwise gfp_t;
  * 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
@@ -256,7 +264,7 @@ typedef unsigned int __bitwise gfp_t;
 #define __GFP_NOLOCKDEP ((__force gfp_t)___GFP_NOLOCKDEP)
 
 /* Room for N __GFP_FOO bits */
-#define __GFP_BITS_SHIFT (27 + IS_ENABLED(CONFIG_LOCKDEP))
+#define __GFP_BITS_SHIFT (28 + IS_ENABLED(CONFIG_LOCKDEP))
 #define __GFP_BITS_MASK ((__force gfp_t)((1 << __GFP_BITS_SHIFT) - 1))
 
 /**
-- 
2.37.2.672.g94769d06f0-goog