mirror of
https://github.com/torvalds/linux.git
synced 2024-12-05 18:41:23 +00:00
ab130f9108
The current page_order() can only be called on pages in the buddy allocator. For compound pages, you have to use compound_order(). This is confusing and led to a bug, so rename page_order() to buddy_order(). Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Link: https://lkml.kernel.org/r/20201001152259.14932-2-willy@infradead.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
365 lines
9.9 KiB
C
365 lines
9.9 KiB
C
// SPDX-License-Identifier: GPL-2.0
|
|
#include <linux/mm.h>
|
|
#include <linux/mmzone.h>
|
|
#include <linux/page_reporting.h>
|
|
#include <linux/gfp.h>
|
|
#include <linux/export.h>
|
|
#include <linux/delay.h>
|
|
#include <linux/scatterlist.h>
|
|
|
|
#include "page_reporting.h"
|
|
#include "internal.h"
|
|
|
|
#define PAGE_REPORTING_DELAY (2 * HZ)
|
|
static struct page_reporting_dev_info __rcu *pr_dev_info __read_mostly;
|
|
|
|
enum {
|
|
PAGE_REPORTING_IDLE = 0,
|
|
PAGE_REPORTING_REQUESTED,
|
|
PAGE_REPORTING_ACTIVE
|
|
};
|
|
|
|
/* request page reporting */
|
|
static void
|
|
__page_reporting_request(struct page_reporting_dev_info *prdev)
|
|
{
|
|
unsigned int state;
|
|
|
|
/* Check to see if we are in desired state */
|
|
state = atomic_read(&prdev->state);
|
|
if (state == PAGE_REPORTING_REQUESTED)
|
|
return;
|
|
|
|
/*
|
|
* If reporting is already active there is nothing we need to do.
|
|
* Test against 0 as that represents PAGE_REPORTING_IDLE.
|
|
*/
|
|
state = atomic_xchg(&prdev->state, PAGE_REPORTING_REQUESTED);
|
|
if (state != PAGE_REPORTING_IDLE)
|
|
return;
|
|
|
|
/*
|
|
* Delay the start of work to allow a sizable queue to build. For
|
|
* now we are limiting this to running no more than once every
|
|
* couple of seconds.
|
|
*/
|
|
schedule_delayed_work(&prdev->work, PAGE_REPORTING_DELAY);
|
|
}
|
|
|
|
/* notify prdev of free page reporting request */
|
|
void __page_reporting_notify(void)
|
|
{
|
|
struct page_reporting_dev_info *prdev;
|
|
|
|
/*
|
|
* We use RCU to protect the pr_dev_info pointer. In almost all
|
|
* cases this should be present, however in the unlikely case of
|
|
* a shutdown this will be NULL and we should exit.
|
|
*/
|
|
rcu_read_lock();
|
|
prdev = rcu_dereference(pr_dev_info);
|
|
if (likely(prdev))
|
|
__page_reporting_request(prdev);
|
|
|
|
rcu_read_unlock();
|
|
}
|
|
|
|
static void
|
|
page_reporting_drain(struct page_reporting_dev_info *prdev,
|
|
struct scatterlist *sgl, unsigned int nents, bool reported)
|
|
{
|
|
struct scatterlist *sg = sgl;
|
|
|
|
/*
|
|
* Drain the now reported pages back into their respective
|
|
* free lists/areas. We assume at least one page is populated.
|
|
*/
|
|
do {
|
|
struct page *page = sg_page(sg);
|
|
int mt = get_pageblock_migratetype(page);
|
|
unsigned int order = get_order(sg->length);
|
|
|
|
__putback_isolated_page(page, order, mt);
|
|
|
|
/* If the pages were not reported due to error skip flagging */
|
|
if (!reported)
|
|
continue;
|
|
|
|
/*
|
|
* If page was not comingled with another page we can
|
|
* consider the result to be "reported" since the page
|
|
* hasn't been modified, otherwise we will need to
|
|
* report on the new larger page when we make our way
|
|
* up to that higher order.
|
|
*/
|
|
if (PageBuddy(page) && buddy_order(page) == order)
|
|
__SetPageReported(page);
|
|
} while ((sg = sg_next(sg)));
|
|
|
|
/* reinitialize scatterlist now that it is empty */
|
|
sg_init_table(sgl, nents);
|
|
}
|
|
|
|
/*
|
|
* The page reporting cycle consists of 4 stages, fill, report, drain, and
|
|
* idle. We will cycle through the first 3 stages until we cannot obtain a
|
|
* full scatterlist of pages, in that case we will switch to idle.
|
|
*/
|
|
static int
|
|
page_reporting_cycle(struct page_reporting_dev_info *prdev, struct zone *zone,
|
|
unsigned int order, unsigned int mt,
|
|
struct scatterlist *sgl, unsigned int *offset)
|
|
{
|
|
struct free_area *area = &zone->free_area[order];
|
|
struct list_head *list = &area->free_list[mt];
|
|
unsigned int page_len = PAGE_SIZE << order;
|
|
struct page *page, *next;
|
|
long budget;
|
|
int err = 0;
|
|
|
|
/*
|
|
* Perform early check, if free area is empty there is
|
|
* nothing to process so we can skip this free_list.
|
|
*/
|
|
if (list_empty(list))
|
|
return err;
|
|
|
|
spin_lock_irq(&zone->lock);
|
|
|
|
/*
|
|
* Limit how many calls we will be making to the page reporting
|
|
* device for this list. By doing this we avoid processing any
|
|
* given list for too long.
|
|
*
|
|
* The current value used allows us enough calls to process over a
|
|
* sixteenth of the current list plus one additional call to handle
|
|
* any pages that may have already been present from the previous
|
|
* list processed. This should result in us reporting all pages on
|
|
* an idle system in about 30 seconds.
|
|
*
|
|
* The division here should be cheap since PAGE_REPORTING_CAPACITY
|
|
* should always be a power of 2.
|
|
*/
|
|
budget = DIV_ROUND_UP(area->nr_free, PAGE_REPORTING_CAPACITY * 16);
|
|
|
|
/* loop through free list adding unreported pages to sg list */
|
|
list_for_each_entry_safe(page, next, list, lru) {
|
|
/* We are going to skip over the reported pages. */
|
|
if (PageReported(page))
|
|
continue;
|
|
|
|
/*
|
|
* If we fully consumed our budget then update our
|
|
* state to indicate that we are requesting additional
|
|
* processing and exit this list.
|
|
*/
|
|
if (budget < 0) {
|
|
atomic_set(&prdev->state, PAGE_REPORTING_REQUESTED);
|
|
next = page;
|
|
break;
|
|
}
|
|
|
|
/* Attempt to pull page from list and place in scatterlist */
|
|
if (*offset) {
|
|
if (!__isolate_free_page(page, order)) {
|
|
next = page;
|
|
break;
|
|
}
|
|
|
|
/* Add page to scatter list */
|
|
--(*offset);
|
|
sg_set_page(&sgl[*offset], page, page_len, 0);
|
|
|
|
continue;
|
|
}
|
|
|
|
/*
|
|
* Make the first non-reported page in the free list
|
|
* the new head of the free list before we release the
|
|
* zone lock.
|
|
*/
|
|
if (!list_is_first(&page->lru, list))
|
|
list_rotate_to_front(&page->lru, list);
|
|
|
|
/* release lock before waiting on report processing */
|
|
spin_unlock_irq(&zone->lock);
|
|
|
|
/* begin processing pages in local list */
|
|
err = prdev->report(prdev, sgl, PAGE_REPORTING_CAPACITY);
|
|
|
|
/* reset offset since the full list was reported */
|
|
*offset = PAGE_REPORTING_CAPACITY;
|
|
|
|
/* update budget to reflect call to report function */
|
|
budget--;
|
|
|
|
/* reacquire zone lock and resume processing */
|
|
spin_lock_irq(&zone->lock);
|
|
|
|
/* flush reported pages from the sg list */
|
|
page_reporting_drain(prdev, sgl, PAGE_REPORTING_CAPACITY, !err);
|
|
|
|
/*
|
|
* Reset next to first entry, the old next isn't valid
|
|
* since we dropped the lock to report the pages
|
|
*/
|
|
next = list_first_entry(list, struct page, lru);
|
|
|
|
/* exit on error */
|
|
if (err)
|
|
break;
|
|
}
|
|
|
|
/* Rotate any leftover pages to the head of the freelist */
|
|
if (&next->lru != list && !list_is_first(&next->lru, list))
|
|
list_rotate_to_front(&next->lru, list);
|
|
|
|
spin_unlock_irq(&zone->lock);
|
|
|
|
return err;
|
|
}
|
|
|
|
static int
|
|
page_reporting_process_zone(struct page_reporting_dev_info *prdev,
|
|
struct scatterlist *sgl, struct zone *zone)
|
|
{
|
|
unsigned int order, mt, leftover, offset = PAGE_REPORTING_CAPACITY;
|
|
unsigned long watermark;
|
|
int err = 0;
|
|
|
|
/* Generate minimum watermark to be able to guarantee progress */
|
|
watermark = low_wmark_pages(zone) +
|
|
(PAGE_REPORTING_CAPACITY << PAGE_REPORTING_MIN_ORDER);
|
|
|
|
/*
|
|
* Cancel request if insufficient free memory or if we failed
|
|
* to allocate page reporting statistics for the zone.
|
|
*/
|
|
if (!zone_watermark_ok(zone, 0, watermark, 0, ALLOC_CMA))
|
|
return err;
|
|
|
|
/* Process each free list starting from lowest order/mt */
|
|
for (order = PAGE_REPORTING_MIN_ORDER; order < MAX_ORDER; order++) {
|
|
for (mt = 0; mt < MIGRATE_TYPES; mt++) {
|
|
/* We do not pull pages from the isolate free list */
|
|
if (is_migrate_isolate(mt))
|
|
continue;
|
|
|
|
err = page_reporting_cycle(prdev, zone, order, mt,
|
|
sgl, &offset);
|
|
if (err)
|
|
return err;
|
|
}
|
|
}
|
|
|
|
/* report the leftover pages before going idle */
|
|
leftover = PAGE_REPORTING_CAPACITY - offset;
|
|
if (leftover) {
|
|
sgl = &sgl[offset];
|
|
err = prdev->report(prdev, sgl, leftover);
|
|
|
|
/* flush any remaining pages out from the last report */
|
|
spin_lock_irq(&zone->lock);
|
|
page_reporting_drain(prdev, sgl, leftover, !err);
|
|
spin_unlock_irq(&zone->lock);
|
|
}
|
|
|
|
return err;
|
|
}
|
|
|
|
static void page_reporting_process(struct work_struct *work)
|
|
{
|
|
struct delayed_work *d_work = to_delayed_work(work);
|
|
struct page_reporting_dev_info *prdev =
|
|
container_of(d_work, struct page_reporting_dev_info, work);
|
|
int err = 0, state = PAGE_REPORTING_ACTIVE;
|
|
struct scatterlist *sgl;
|
|
struct zone *zone;
|
|
|
|
/*
|
|
* Change the state to "Active" so that we can track if there is
|
|
* anyone requests page reporting after we complete our pass. If
|
|
* the state is not altered by the end of the pass we will switch
|
|
* to idle and quit scheduling reporting runs.
|
|
*/
|
|
atomic_set(&prdev->state, state);
|
|
|
|
/* allocate scatterlist to store pages being reported on */
|
|
sgl = kmalloc_array(PAGE_REPORTING_CAPACITY, sizeof(*sgl), GFP_KERNEL);
|
|
if (!sgl)
|
|
goto err_out;
|
|
|
|
sg_init_table(sgl, PAGE_REPORTING_CAPACITY);
|
|
|
|
for_each_zone(zone) {
|
|
err = page_reporting_process_zone(prdev, sgl, zone);
|
|
if (err)
|
|
break;
|
|
}
|
|
|
|
kfree(sgl);
|
|
err_out:
|
|
/*
|
|
* If the state has reverted back to requested then there may be
|
|
* additional pages to be processed. We will defer for 2s to allow
|
|
* more pages to accumulate.
|
|
*/
|
|
state = atomic_cmpxchg(&prdev->state, state, PAGE_REPORTING_IDLE);
|
|
if (state == PAGE_REPORTING_REQUESTED)
|
|
schedule_delayed_work(&prdev->work, PAGE_REPORTING_DELAY);
|
|
}
|
|
|
|
static DEFINE_MUTEX(page_reporting_mutex);
|
|
DEFINE_STATIC_KEY_FALSE(page_reporting_enabled);
|
|
|
|
int page_reporting_register(struct page_reporting_dev_info *prdev)
|
|
{
|
|
int err = 0;
|
|
|
|
mutex_lock(&page_reporting_mutex);
|
|
|
|
/* nothing to do if already in use */
|
|
if (rcu_access_pointer(pr_dev_info)) {
|
|
err = -EBUSY;
|
|
goto err_out;
|
|
}
|
|
|
|
/* initialize state and work structures */
|
|
atomic_set(&prdev->state, PAGE_REPORTING_IDLE);
|
|
INIT_DELAYED_WORK(&prdev->work, &page_reporting_process);
|
|
|
|
/* Begin initial flush of zones */
|
|
__page_reporting_request(prdev);
|
|
|
|
/* Assign device to allow notifications */
|
|
rcu_assign_pointer(pr_dev_info, prdev);
|
|
|
|
/* enable page reporting notification */
|
|
if (!static_key_enabled(&page_reporting_enabled)) {
|
|
static_branch_enable(&page_reporting_enabled);
|
|
pr_info("Free page reporting enabled\n");
|
|
}
|
|
err_out:
|
|
mutex_unlock(&page_reporting_mutex);
|
|
|
|
return err;
|
|
}
|
|
EXPORT_SYMBOL_GPL(page_reporting_register);
|
|
|
|
void page_reporting_unregister(struct page_reporting_dev_info *prdev)
|
|
{
|
|
mutex_lock(&page_reporting_mutex);
|
|
|
|
if (rcu_access_pointer(pr_dev_info) == prdev) {
|
|
/* Disable page reporting notification */
|
|
RCU_INIT_POINTER(pr_dev_info, NULL);
|
|
synchronize_rcu();
|
|
|
|
/* Flush any existing work, and lock it out */
|
|
cancel_delayed_work_sync(&prdev->work);
|
|
}
|
|
|
|
mutex_unlock(&page_reporting_mutex);
|
|
}
|
|
EXPORT_SYMBOL_GPL(page_reporting_unregister);
|