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![sh_def@163.com](/assets/img/avatar_default.png)
Replace '&next->lru != list' with list_entry_is_head(). No functional change. Link: https://lkml.kernel.org/r/20201222182735.GA1257912@ubuntu-A520I-AC Signed-off-by: sh <sh_def@163.com> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Cc: Alexander Duyck <alexander.h.duyck@linux.intel.com> Reviewed-by: David Hildenbrand <david@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
364 lines
9.9 KiB
C
364 lines
9.9 KiB
C
// SPDX-License-Identifier: GPL-2.0
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#include <linux/mm.h>
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#include <linux/mmzone.h>
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#include <linux/page_reporting.h>
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#include <linux/gfp.h>
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#include <linux/export.h>
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#include <linux/delay.h>
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#include <linux/scatterlist.h>
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#include "page_reporting.h"
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#include "internal.h"
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#define PAGE_REPORTING_DELAY (2 * HZ)
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static struct page_reporting_dev_info __rcu *pr_dev_info __read_mostly;
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enum {
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PAGE_REPORTING_IDLE = 0,
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PAGE_REPORTING_REQUESTED,
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PAGE_REPORTING_ACTIVE
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};
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/* request page reporting */
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static void
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__page_reporting_request(struct page_reporting_dev_info *prdev)
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{
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unsigned int state;
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/* Check to see if we are in desired state */
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state = atomic_read(&prdev->state);
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if (state == PAGE_REPORTING_REQUESTED)
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return;
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/*
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* If reporting is already active there is nothing we need to do.
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* Test against 0 as that represents PAGE_REPORTING_IDLE.
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*/
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state = atomic_xchg(&prdev->state, PAGE_REPORTING_REQUESTED);
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if (state != PAGE_REPORTING_IDLE)
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return;
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/*
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* Delay the start of work to allow a sizable queue to build. For
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* now we are limiting this to running no more than once every
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* couple of seconds.
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*/
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schedule_delayed_work(&prdev->work, PAGE_REPORTING_DELAY);
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}
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/* notify prdev of free page reporting request */
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void __page_reporting_notify(void)
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{
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struct page_reporting_dev_info *prdev;
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/*
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* We use RCU to protect the pr_dev_info pointer. In almost all
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* cases this should be present, however in the unlikely case of
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* a shutdown this will be NULL and we should exit.
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*/
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rcu_read_lock();
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prdev = rcu_dereference(pr_dev_info);
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if (likely(prdev))
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__page_reporting_request(prdev);
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rcu_read_unlock();
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}
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static void
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page_reporting_drain(struct page_reporting_dev_info *prdev,
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struct scatterlist *sgl, unsigned int nents, bool reported)
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{
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struct scatterlist *sg = sgl;
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/*
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* Drain the now reported pages back into their respective
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* free lists/areas. We assume at least one page is populated.
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*/
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do {
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struct page *page = sg_page(sg);
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int mt = get_pageblock_migratetype(page);
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unsigned int order = get_order(sg->length);
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__putback_isolated_page(page, order, mt);
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/* If the pages were not reported due to error skip flagging */
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if (!reported)
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continue;
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/*
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* If page was not comingled with another page we can
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* consider the result to be "reported" since the page
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* hasn't been modified, otherwise we will need to
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* report on the new larger page when we make our way
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* up to that higher order.
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*/
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if (PageBuddy(page) && buddy_order(page) == order)
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__SetPageReported(page);
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} while ((sg = sg_next(sg)));
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/* reinitialize scatterlist now that it is empty */
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sg_init_table(sgl, nents);
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}
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/*
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* The page reporting cycle consists of 4 stages, fill, report, drain, and
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* idle. We will cycle through the first 3 stages until we cannot obtain a
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* full scatterlist of pages, in that case we will switch to idle.
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*/
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static int
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page_reporting_cycle(struct page_reporting_dev_info *prdev, struct zone *zone,
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unsigned int order, unsigned int mt,
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struct scatterlist *sgl, unsigned int *offset)
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{
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struct free_area *area = &zone->free_area[order];
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struct list_head *list = &area->free_list[mt];
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unsigned int page_len = PAGE_SIZE << order;
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struct page *page, *next;
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long budget;
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int err = 0;
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/*
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* Perform early check, if free area is empty there is
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* nothing to process so we can skip this free_list.
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*/
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if (list_empty(list))
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return err;
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spin_lock_irq(&zone->lock);
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/*
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* Limit how many calls we will be making to the page reporting
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* device for this list. By doing this we avoid processing any
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* given list for too long.
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*
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* The current value used allows us enough calls to process over a
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* sixteenth of the current list plus one additional call to handle
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* any pages that may have already been present from the previous
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* list processed. This should result in us reporting all pages on
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* an idle system in about 30 seconds.
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*
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* The division here should be cheap since PAGE_REPORTING_CAPACITY
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* should always be a power of 2.
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*/
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budget = DIV_ROUND_UP(area->nr_free, PAGE_REPORTING_CAPACITY * 16);
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/* loop through free list adding unreported pages to sg list */
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list_for_each_entry_safe(page, next, list, lru) {
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/* We are going to skip over the reported pages. */
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if (PageReported(page))
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continue;
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/*
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* If we fully consumed our budget then update our
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* state to indicate that we are requesting additional
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* processing and exit this list.
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*/
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if (budget < 0) {
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atomic_set(&prdev->state, PAGE_REPORTING_REQUESTED);
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next = page;
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break;
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}
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/* Attempt to pull page from list and place in scatterlist */
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if (*offset) {
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if (!__isolate_free_page(page, order)) {
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next = page;
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break;
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}
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/* Add page to scatter list */
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--(*offset);
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sg_set_page(&sgl[*offset], page, page_len, 0);
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continue;
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}
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/*
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* Make the first non-reported page in the free list
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* the new head of the free list before we release the
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* zone lock.
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*/
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if (!list_is_first(&page->lru, list))
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list_rotate_to_front(&page->lru, list);
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/* release lock before waiting on report processing */
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spin_unlock_irq(&zone->lock);
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/* begin processing pages in local list */
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err = prdev->report(prdev, sgl, PAGE_REPORTING_CAPACITY);
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/* reset offset since the full list was reported */
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*offset = PAGE_REPORTING_CAPACITY;
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/* update budget to reflect call to report function */
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budget--;
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/* reacquire zone lock and resume processing */
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spin_lock_irq(&zone->lock);
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/* flush reported pages from the sg list */
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page_reporting_drain(prdev, sgl, PAGE_REPORTING_CAPACITY, !err);
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/*
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* Reset next to first entry, the old next isn't valid
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* since we dropped the lock to report the pages
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*/
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next = list_first_entry(list, struct page, lru);
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/* exit on error */
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if (err)
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break;
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}
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/* Rotate any leftover pages to the head of the freelist */
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if (!list_entry_is_head(next, list, lru) && !list_is_first(&next->lru, list))
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list_rotate_to_front(&next->lru, list);
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spin_unlock_irq(&zone->lock);
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return err;
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}
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static int
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page_reporting_process_zone(struct page_reporting_dev_info *prdev,
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struct scatterlist *sgl, struct zone *zone)
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{
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unsigned int order, mt, leftover, offset = PAGE_REPORTING_CAPACITY;
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unsigned long watermark;
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int err = 0;
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/* Generate minimum watermark to be able to guarantee progress */
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watermark = low_wmark_pages(zone) +
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(PAGE_REPORTING_CAPACITY << PAGE_REPORTING_MIN_ORDER);
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/*
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* Cancel request if insufficient free memory or if we failed
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* to allocate page reporting statistics for the zone.
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*/
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if (!zone_watermark_ok(zone, 0, watermark, 0, ALLOC_CMA))
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return err;
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/* Process each free list starting from lowest order/mt */
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for (order = PAGE_REPORTING_MIN_ORDER; order < MAX_ORDER; order++) {
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for (mt = 0; mt < MIGRATE_TYPES; mt++) {
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/* We do not pull pages from the isolate free list */
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if (is_migrate_isolate(mt))
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continue;
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err = page_reporting_cycle(prdev, zone, order, mt,
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sgl, &offset);
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if (err)
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return err;
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}
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}
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/* report the leftover pages before going idle */
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leftover = PAGE_REPORTING_CAPACITY - offset;
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if (leftover) {
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sgl = &sgl[offset];
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err = prdev->report(prdev, sgl, leftover);
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/* flush any remaining pages out from the last report */
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spin_lock_irq(&zone->lock);
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page_reporting_drain(prdev, sgl, leftover, !err);
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spin_unlock_irq(&zone->lock);
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}
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return err;
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}
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static void page_reporting_process(struct work_struct *work)
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{
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struct delayed_work *d_work = to_delayed_work(work);
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struct page_reporting_dev_info *prdev =
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container_of(d_work, struct page_reporting_dev_info, work);
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int err = 0, state = PAGE_REPORTING_ACTIVE;
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struct scatterlist *sgl;
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struct zone *zone;
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/*
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* Change the state to "Active" so that we can track if there is
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* anyone requests page reporting after we complete our pass. If
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* the state is not altered by the end of the pass we will switch
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* to idle and quit scheduling reporting runs.
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*/
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atomic_set(&prdev->state, state);
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/* allocate scatterlist to store pages being reported on */
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sgl = kmalloc_array(PAGE_REPORTING_CAPACITY, sizeof(*sgl), GFP_KERNEL);
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if (!sgl)
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goto err_out;
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sg_init_table(sgl, PAGE_REPORTING_CAPACITY);
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for_each_zone(zone) {
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err = page_reporting_process_zone(prdev, sgl, zone);
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if (err)
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break;
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}
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kfree(sgl);
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err_out:
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/*
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* If the state has reverted back to requested then there may be
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* additional pages to be processed. We will defer for 2s to allow
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* more pages to accumulate.
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*/
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state = atomic_cmpxchg(&prdev->state, state, PAGE_REPORTING_IDLE);
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if (state == PAGE_REPORTING_REQUESTED)
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schedule_delayed_work(&prdev->work, PAGE_REPORTING_DELAY);
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}
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static DEFINE_MUTEX(page_reporting_mutex);
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DEFINE_STATIC_KEY_FALSE(page_reporting_enabled);
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int page_reporting_register(struct page_reporting_dev_info *prdev)
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{
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int err = 0;
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mutex_lock(&page_reporting_mutex);
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/* nothing to do if already in use */
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if (rcu_access_pointer(pr_dev_info)) {
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err = -EBUSY;
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goto err_out;
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}
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/* initialize state and work structures */
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atomic_set(&prdev->state, PAGE_REPORTING_IDLE);
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INIT_DELAYED_WORK(&prdev->work, &page_reporting_process);
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/* Begin initial flush of zones */
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__page_reporting_request(prdev);
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/* Assign device to allow notifications */
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rcu_assign_pointer(pr_dev_info, prdev);
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/* enable page reporting notification */
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if (!static_key_enabled(&page_reporting_enabled)) {
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static_branch_enable(&page_reporting_enabled);
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pr_info("Free page reporting enabled\n");
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}
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err_out:
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mutex_unlock(&page_reporting_mutex);
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return err;
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}
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EXPORT_SYMBOL_GPL(page_reporting_register);
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void page_reporting_unregister(struct page_reporting_dev_info *prdev)
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{
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mutex_lock(&page_reporting_mutex);
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if (rcu_access_pointer(pr_dev_info) == prdev) {
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/* Disable page reporting notification */
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RCU_INIT_POINTER(pr_dev_info, NULL);
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synchronize_rcu();
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/* Flush any existing work, and lock it out */
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cancel_delayed_work_sync(&prdev->work);
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}
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mutex_unlock(&page_reporting_mutex);
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}
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EXPORT_SYMBOL_GPL(page_reporting_unregister);
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