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mm,page_owner: implement the tracking of the stacks count

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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.

Link: https://lkml.kernel.org/r/20240215215907.20121-5-osalvador@suse.de
Signed-off-by: Oscar Salvador <osalvador@suse.de>
Reviewed-by: Marco Elver <elver@google.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Oscar Salvador 2024-02-15 22:59:04 +01:00 committed by Andrew Morton
parent 4bedfb314b
commit 217b2119b9
1 changed files with 72 additions and 1 deletions
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73
mm/page_owner.c
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@ -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);
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;
}
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 &= ~GFP_ZONEMASK;
gfp_mask &= (GFP_ATOMIC | GFP_KERNEL);
gfp_mask |= __GFP_NOWARN;
stack = kmalloc(sizeof(*stack), gfp_mask);
if (!stack)
return;
stack->stack_record = stack_record;
stack->next = NULL;
spin_lock_irqsave(&stack_list_lock, flags);
stack->next = stack_list;
stack_list = 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 = __stack_depot_get_stack_record(handle);
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) == REFCOUNT_SATURATED) {
int old = 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 = __stack_depot_get_stack_record(handle);
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 = local_clock();
@ -162,17 +220,29 @@ void __reset_page_owner(struct page *page, unsigned short order)
if (unlikely(!page_ext))
return;
page_owner = get_page_owner(page_ext);
alloc_handle = page_owner->handle;
handle = save_stack(GFP_NOWAIT | __GFP_NOWARN);
for (i = 0; i < (1 << order); i++) {
__clear_bit(PAGE_EXT_OWNER_ALLOCATED, &page_ext->flags);
page_owner = get_page_owner(page_ext);
page_owner->free_handle = handle;
page_owner->free_ts_nsec = free_ts_nsec;
page_owner->free_pid = current->pid;
page_owner->free_tgid = current->tgid;
page_ext = page_ext_next(page_ext);
page_owner = get_page_owner(page_ext);
}
page_ext_put(page_ext);
if (alloc_handle != 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);
}
static inline void __set_page_owner_handle(struct page_ext *page_ext,
@ -214,6 +284,7 @@ noinline void __set_page_owner(struct page *page, unsigned 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);
}
void __set_page_owner_migrate_reason(struct page *page, int reason)