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Message-ID: <CANpmjNMnobv_KRnas6pfe0NKUbrOgRocN134yq3-0ODmsc3-nw@mail.gmail.com>
Date: Tue, 13 Feb 2024 09:26:09 +0100
From: Marco Elver <elver@...gle.com>
To: Oscar Salvador <osalvador@...e.de>
Cc: Andrew Morton <akpm@...ux-foundation.org>, linux-kernel@...r.kernel.org,
linux-mm@...ck.org, Michal Hocko <mhocko@...e.com>, Vlastimil Babka <vbabka@...e.cz>,
Andrey Konovalov <andreyknvl@...il.com>, Alexander Potapenko <glider@...gle.com>
Subject: Re: [PATCH v8 1/5] lib/stackdepot: Move stack_record struct
definition into the header
On Mon, 12 Feb 2024 at 23:29, Oscar Salvador <osalvador@...e.de> wrote:
>
> In order to move the heavy lifting into page_owner code, this one
> needs to have access to the stack_record structure, which right now
> sits in lib/stackdepot.c.
> Move it to the stackdepot.h header so page_owner can access
> stack_record's struct fields.
>
> Signed-off-by: Oscar Salvador <osalvador@...e.de>
Reviewed-by: Marco Elver <elver@...gle.com>
> ---
> include/linux/stackdepot.h | 44 ++++++++++++++++++++++++++++++++++++++
> lib/stackdepot.c | 43 -------------------------------------
> 2 files changed, 44 insertions(+), 43 deletions(-)
>
> diff --git a/include/linux/stackdepot.h b/include/linux/stackdepot.h
> index adcbb8f23600..90274860fd8e 100644
> --- a/include/linux/stackdepot.h
> +++ b/include/linux/stackdepot.h
> @@ -30,6 +30,50 @@ typedef u32 depot_stack_handle_t;
> */
> #define STACK_DEPOT_EXTRA_BITS 5
>
> +#define DEPOT_HANDLE_BITS (sizeof(depot_stack_handle_t) * 8)
> +
> +#define DEPOT_POOL_ORDER 2 /* Pool size order, 4 pages */
> +#define DEPOT_POOL_SIZE (1LL << (PAGE_SHIFT + DEPOT_POOL_ORDER))
> +#define DEPOT_STACK_ALIGN 4
> +#define DEPOT_OFFSET_BITS (DEPOT_POOL_ORDER + PAGE_SHIFT - DEPOT_STACK_ALIGN)
> +#define DEPOT_POOL_INDEX_BITS (DEPOT_HANDLE_BITS - DEPOT_OFFSET_BITS - \
> + STACK_DEPOT_EXTRA_BITS)
> +
> +/* Compact structure that stores a reference to a stack. */
> +union handle_parts {
> + depot_stack_handle_t handle;
> + struct {
> + u32 pool_index : DEPOT_POOL_INDEX_BITS;
> + u32 offset : DEPOT_OFFSET_BITS;
> + u32 extra : STACK_DEPOT_EXTRA_BITS;
> + };
> +};
> +
> +struct stack_record {
> + struct list_head hash_list; /* Links in the hash table */
> + u32 hash; /* Hash in hash table */
> + u32 size; /* Number of stored frames */
> + union handle_parts handle; /* Constant after initialization */
> + refcount_t count;
> + union {
> + unsigned long entries[CONFIG_STACKDEPOT_MAX_FRAMES]; /* Frames */
> + struct {
> + /*
> + * An important invariant of the implementation is to
> + * only place a stack record onto the freelist iff its
> + * refcount is zero. Because stack records with a zero
> + * refcount are never considered as valid, it is safe to
> + * union @entries and freelist management state below.
> + * Conversely, as soon as an entry is off the freelist
> + * and its refcount becomes non-zero, the below must not
> + * be accessed until being placed back on the freelist.
> + */
> + struct list_head free_list; /* Links in the freelist */
> + unsigned long rcu_state; /* RCU cookie */
> + };
> + };
> +};
> +
> typedef u32 depot_flags_t;
>
> /*
> diff --git a/lib/stackdepot.c b/lib/stackdepot.c
> index 4a7055a63d9f..6f9095374847 100644
> --- a/lib/stackdepot.c
> +++ b/lib/stackdepot.c
> @@ -36,54 +36,11 @@
> #include <linux/memblock.h>
> #include <linux/kasan-enabled.h>
>
> -#define DEPOT_HANDLE_BITS (sizeof(depot_stack_handle_t) * 8)
> -
> -#define DEPOT_POOL_ORDER 2 /* Pool size order, 4 pages */
> -#define DEPOT_POOL_SIZE (1LL << (PAGE_SHIFT + DEPOT_POOL_ORDER))
> -#define DEPOT_STACK_ALIGN 4
> -#define DEPOT_OFFSET_BITS (DEPOT_POOL_ORDER + PAGE_SHIFT - DEPOT_STACK_ALIGN)
> -#define DEPOT_POOL_INDEX_BITS (DEPOT_HANDLE_BITS - DEPOT_OFFSET_BITS - \
> - STACK_DEPOT_EXTRA_BITS)
> #define DEPOT_POOLS_CAP 8192
> #define DEPOT_MAX_POOLS \
> (((1LL << (DEPOT_POOL_INDEX_BITS)) < DEPOT_POOLS_CAP) ? \
> (1LL << (DEPOT_POOL_INDEX_BITS)) : DEPOT_POOLS_CAP)
>
> -/* Compact structure that stores a reference to a stack. */
> -union handle_parts {
> - depot_stack_handle_t handle;
> - struct {
> - u32 pool_index : DEPOT_POOL_INDEX_BITS;
> - u32 offset : DEPOT_OFFSET_BITS;
> - u32 extra : STACK_DEPOT_EXTRA_BITS;
> - };
> -};
> -
> -struct stack_record {
> - struct list_head hash_list; /* Links in the hash table */
> - u32 hash; /* Hash in hash table */
> - u32 size; /* Number of stored frames */
> - union handle_parts handle; /* Constant after initialization */
> - refcount_t count;
> - union {
> - unsigned long entries[CONFIG_STACKDEPOT_MAX_FRAMES]; /* Frames */
> - struct {
> - /*
> - * An important invariant of the implementation is to
> - * only place a stack record onto the freelist iff its
> - * refcount is zero. Because stack records with a zero
> - * refcount are never considered as valid, it is safe to
> - * union @entries and freelist management state below.
> - * Conversely, as soon as an entry is off the freelist
> - * and its refcount becomes non-zero, the below must not
> - * be accessed until being placed back on the freelist.
> - */
> - struct list_head free_list; /* Links in the freelist */
> - unsigned long rcu_state; /* RCU cookie */
> - };
> - };
> -};
> -
> static bool stack_depot_disabled;
> static bool __stack_depot_early_init_requested __initdata = IS_ENABLED(CONFIG_STACKDEPOT_ALWAYS_INIT);
> static bool __stack_depot_early_init_passed __initdata;
> --
> 2.43.0
>
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