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charset="utf-8" Implement {inc,dec}_stack_record_count() which increments or decrements on respective allocation and free operations, via __reset_page_owner() (free operation) and __set_page_owner() (alloc operation). Newly allocated stack_record structs will be added to the list stack_list via add_stack_record_to_list(). Modifications on the list are protected via a spinlock with irqs disabled, since this code can also be reached from IRQ context. Signed-off-by: Oscar Salvador Reviewed-by: Marco Elver Reviewed-by: Vlastimil Babka --- mm/page_owner.c | 73 ++++++++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 72 insertions(+), 1 deletion(-) diff --git a/mm/page_owner.c b/mm/page_owner.c index 33e342b15d9b..df6a923af5de 100644 --- a/mm/page_owner.c +++ b/mm/page_owner.c @@ -43,6 +43,7 @@ struct stack { static struct stack dummy_stack; static struct stack failure_stack; static struct stack *stack_list; +static DEFINE_SPINLOCK(stack_list_lock); =20 static bool page_owner_enabled __initdata; DEFINE_STATIC_KEY_FALSE(page_owner_inited); @@ -150,11 +151,68 @@ static noinline depot_stack_handle_t save_stack(gfp_t= flags) return handle; } =20 +static void add_stack_record_to_list(struct stack_record *stack_record, + gfp_t gfp_mask) +{ + unsigned long flags; + struct stack *stack; + + /* Filter gfp_mask the same way stackdepot does, for consistency */ + gfp_mask &=3D ~GFP_ZONEMASK; + gfp_mask &=3D (GFP_ATOMIC | GFP_KERNEL); + gfp_mask |=3D __GFP_NOWARN; + + stack =3D kmalloc(sizeof(*stack), gfp_mask); + if (!stack) + return; + + stack->stack_record =3D stack_record; + stack->next =3D NULL; + + spin_lock_irqsave(&stack_list_lock, flags); + stack->next =3D stack_list; + stack_list =3D stack; + spin_unlock_irqrestore(&stack_list_lock, flags); +} + +static void inc_stack_record_count(depot_stack_handle_t handle, gfp_t gfp_= mask) +{ + struct stack_record *stack_record =3D __stack_depot_get_stack_record(hand= le); + + if (!stack_record) + return; + + /* + * New stack_record's that do not use STACK_DEPOT_FLAG_GET start + * with REFCOUNT_SATURATED to catch spurious increments of their + * refcount. + * Since we do not use STACK_DEPOT_FLAG_GET API, let us + * set a refcount of 1 ourselves. + */ + if (refcount_read(&stack_record->count) =3D=3D REFCOUNT_SATURATED) { + int old =3D REFCOUNT_SATURATED; + + if (atomic_try_cmpxchg_relaxed(&stack_record->count.refs, &old, 1)) + /* Add the new stack_record to our list */ + add_stack_record_to_list(stack_record, gfp_mask); + } + refcount_inc(&stack_record->count); +} + +static void dec_stack_record_count(depot_stack_handle_t handle) +{ + struct stack_record *stack_record =3D __stack_depot_get_stack_record(hand= le); + + if (stack_record) + refcount_dec(&stack_record->count); +} + void __reset_page_owner(struct page *page, unsigned short order) { int i; struct page_ext *page_ext; depot_stack_handle_t handle; + depot_stack_handle_t alloc_handle; struct page_owner *page_owner; u64 free_ts_nsec =3D local_clock(); =20 @@ -162,17 +220,29 @@ void __reset_page_owner(struct page *page, unsigned s= hort order) if (unlikely(!page_ext)) return; =20 + page_owner =3D get_page_owner(page_ext); + alloc_handle =3D page_owner->handle; + handle =3D save_stack(GFP_NOWAIT | __GFP_NOWARN); for (i =3D 0; i < (1 << order); i++) { __clear_bit(PAGE_EXT_OWNER_ALLOCATED, &page_ext->flags); - page_owner =3D get_page_owner(page_ext); page_owner->free_handle =3D handle; page_owner->free_ts_nsec =3D free_ts_nsec; page_owner->free_pid =3D current->pid; page_owner->free_tgid =3D current->tgid; page_ext =3D page_ext_next(page_ext); + page_owner =3D get_page_owner(page_ext); } page_ext_put(page_ext); + if (alloc_handle !=3D early_handle) + /* + * early_handle is being set as a handle for all those + * early allocated pages. See init_pages_in_zone(). + * Since their refcount is not being incremented because + * the machinery is not ready yet, we cannot decrement + * their refcount either. + */ + dec_stack_record_count(alloc_handle); } =20 static inline void __set_page_owner_handle(struct page_ext *page_ext, @@ -214,6 +284,7 @@ noinline void __set_page_owner(struct page *page, unsig= ned short order, return; __set_page_owner_handle(page_ext, handle, order, gfp_mask); page_ext_put(page_ext); + inc_stack_record_count(handle, gfp_mask); } =20 void __set_page_owner_migrate_reason(struct page *page, int reason) --=20 2.43.0