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375 lines
10 KiB
375 lines
10 KiB
// 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/module.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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unsigned int page_reporting_order = MAX_ORDER; |
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module_param(page_reporting_order, uint, 0644); |
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MODULE_PARM_DESC(page_reporting_order, "Set page reporting order"); |
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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_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_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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/* |
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* Update the page reporting order if it's specified by driver. |
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* Otherwise, it falls back to @pageblock_order. |
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*/ |
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page_reporting_order = prdev->order ? : pageblock_order; |
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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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