Re: [PATCH v5 16/18] mm: remove the __GFP_NO_OBJ_EXT flag

[Hao Ge <hao.ge@linux.dev>]

On 2026/7/3 20:31, Brendan Jackman wrote:
> From: "Vlastimil Babka (SUSE)" <vbabka@kernel.org>
>
> All users of the flag are converted to SLAB_ALLOC_NO_RECURSE or
> ALLOC_NO_CODETAG (from __GFP_NO_CODETAG which reused the NO_OBJ_EXT bit).
> Free up the flag bit.
>
> Signed-off-by: Vlastimil Babka (SUSE) <vbabka@kernel.org>
> [Rebased onto __GFP_NO_CODETAG removal]
> Signed-off-by: Brendan Jackman <jackmanb@google.com>


Acked-by: Hao Ge <hao.ge@linux.dev>


> ---
>   include/linux/gfp_types.h       |  7 -------
>   include/trace/events/mmflags.h  | 10 +---------
>   tools/include/linux/gfp_types.h |  7 -------
>   3 files changed, 1 insertion(+), 23 deletions(-)
>
> diff --git a/include/linux/gfp_types.h b/include/linux/gfp_types.h
> index 463b551d12d99..190191411009f 100644
> --- a/include/linux/gfp_types.h
> +++ b/include/linux/gfp_types.h
> @@ -55,7 +55,6 @@ enum {
>   #ifdef CONFIG_LOCKDEP
>   	___GFP_NOLOCKDEP_BIT,
>   #endif
> -	___GFP_NO_OBJ_EXT_BIT,
>   	___GFP_LAST_BIT
>   };
>   
> @@ -96,7 +95,6 @@ enum {
>   #else
>   #define ___GFP_NOLOCKDEP	0
>   #endif
> -#define ___GFP_NO_OBJ_EXT       BIT(___GFP_NO_OBJ_EXT_BIT)
>   
>   /*
>    * Physical address zone modifiers (see linux/mmzone.h - low four bits)
> @@ -138,17 +136,12 @@ enum {
>    *
>    * %__GFP_ACCOUNT causes the allocation to be accounted to the active
>    * cgroup context.
> - *
> - * %__GFP_NO_OBJ_EXT causes slab allocation to have no object extension.
> - * mark_obj_codetag_empty() should be called upon freeing for objects allocated
> - * with this flag to indicate that their NULL tags are expected and normal.
>    */
>   #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
> diff --git a/include/trace/events/mmflags.h b/include/trace/events/mmflags.h
> index a6e5a44c9b429..c1a05ff0feab0 100644
> --- a/include/trace/events/mmflags.h
> +++ b/include/trace/events/mmflags.h
> @@ -54,18 +54,10 @@
>   # define TRACE_GFP_FLAGS_LOCKDEP
>   #endif
>   
> -#ifdef CONFIG_SLAB_OBJ_EXT
> -# define TRACE_GFP_FLAGS_SLAB			\
> -	TRACE_GFP_EM(NO_OBJ_EXT)
> -#else
> -# define TRACE_GFP_FLAGS_SLAB
> -#endif
> -
>   #define TRACE_GFP_FLAGS				\
>   	TRACE_GFP_FLAGS_GENERAL			\
>   	TRACE_GFP_FLAGS_KASAN			\
> -	TRACE_GFP_FLAGS_LOCKDEP			\
> -	TRACE_GFP_FLAGS_SLAB
> +	TRACE_GFP_FLAGS_LOCKDEP
>   
>   #undef TRACE_GFP_EM
>   #define TRACE_GFP_EM(a) TRACE_DEFINE_ENUM(___GFP_##a##_BIT);
> diff --git a/tools/include/linux/gfp_types.h b/tools/include/linux/gfp_types.h
> index 6c75df30a281d..a93b8bd200b76 100644
> --- a/tools/include/linux/gfp_types.h
> +++ b/tools/include/linux/gfp_types.h
> @@ -55,7 +55,6 @@ enum {
>   #ifdef CONFIG_LOCKDEP
>   	___GFP_NOLOCKDEP_BIT,
>   #endif
> -	___GFP_NO_OBJ_EXT_BIT,
>   	___GFP_LAST_BIT
>   };
>   
> @@ -96,7 +95,6 @@ enum {
>   #else
>   #define ___GFP_NOLOCKDEP	0
>   #endif
> -#define ___GFP_NO_OBJ_EXT       BIT(___GFP_NO_OBJ_EXT_BIT)
>   
>   /*
>    * Physical address zone modifiers (see linux/mmzone.h - low four bits)
> @@ -137,17 +135,12 @@ 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.
> - * mark_obj_codetag_empty() should be called upon freeing for objects allocated
> - * with this flag to indicate that their NULL tags are expected and normal.
>    */
>   #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
>