In Joonsoo's CMA patch "CMA: always treat free cma pages as non-free on
watermark checking" [1], it changes __zone_watermark_ok to substruct CMA
pages number from free_pages if system use CMA:
if (IS_ENABLED(CONFIG_CMA) && z->managed_cma_pages)
free_pages -= zone_page_state(z, NR_FREE_CMA_PAGES);
But after this part of code
for (o = 0; o < order; o++) {
/* At the next order, this order's pages become unavailable */
free_pages -= z->free_area[o].nr_free << o;
CMA memory in each order is part of z->free_area[o].nr_free, then the CMA
page number of this order is substructed twice. This bug will make
__zone_watermark_ok return more false.
This patch add cma_free_area to struct free_area that just record the number
of CMA pages. And add it back in the order loop to handle the substruct
twice issue.
[1] https://lkml.org/lkml/2014/5/28/110
Signed-off-by: Hui Zhu <zhuhui@xxxxxxxxxx>
Signed-off-by: Weixing Liu <liuweixing@xxxxxxxxxx>
---
include/linux/mmzone.h | 3 +++
mm/page_alloc.c | 29 ++++++++++++++++++++++++++++-
2 files changed, 31 insertions(+), 1 deletion(-)
diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index ee1ce1f..7ccad93 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -92,6 +92,9 @@ static inline int get_pfnblock_migratetype(struct page *page, unsigned long pfn)
struct free_area {
struct list_head free_list[MIGRATE_TYPES];
unsigned long nr_free;
+#ifdef CONFIG_CMA
+ unsigned long cma_nr_free;
+#endif
};
struct pglist_data;
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 1b6c82c..a8d9f03 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -650,6 +650,8 @@ static inline void __free_one_page(struct page *page,
} else {
list_del(&buddy->lru);
zone->free_area[order].nr_free--;
+ if (is_migrate_cma(migratetype))
+ zone->free_area[order].cma_nr_free--;
rmv_page_order(buddy);
}
combined_idx = buddy_idx & page_idx;
@@ -683,6 +685,8 @@ static inline void __free_one_page(struct page *page,
list_add(&page->lru, &zone->free_area[order].free_list[migratetype]);
out:
zone->free_area[order].nr_free++;
+ if (is_migrate_cma(migratetype))
+ zone->free_area[order].cma_nr_free++;
}
static inline int free_pages_check(struct page *page)
@@ -987,6 +991,8 @@ static inline void expand(struct zone *zone, struct page *page,
}
list_add(&page[size].lru, &area->free_list[migratetype]);
area->nr_free++;
+ if (is_migrate_cma(migratetype))
+ area->cma_nr_free++;
set_page_order(&page[size], high);
}
}
@@ -1070,6 +1076,8 @@ struct page *__rmqueue_smallest(struct zone *zone, unsigned int order,
list_del(&page->lru);
rmv_page_order(page);
area->nr_free--;
+ if (is_migrate_cma(migratetype))
+ area->cma_nr_free--;
expand(zone, page, order, current_order, area, migratetype);
set_freepage_migratetype(page, migratetype);
return page;
@@ -1258,6 +1266,8 @@ __rmqueue_fallback(struct zone *zone, unsigned int order, int start_migratetype)
page = list_entry(area->free_list[migratetype].next,
struct page, lru);
area->nr_free--;
+ if (is_migrate_cma(migratetype))
+ area->cma_nr_free--;
new_type = try_to_steal_freepages(zone, page,
start_migratetype,
@@ -1682,6 +1692,8 @@ int __isolate_free_page(struct page *page, unsigned int order)
/* Remove page from free list */
list_del(&page->lru);
zone->free_area[order].nr_free--;
+ if (is_migrate_cma(mt))
+ zone->free_area[order].cma_nr_free--;
rmv_page_order(page);
/* Set the pageblock if the isolated page is at least a pageblock */
@@ -1893,6 +1905,9 @@ static bool __zone_watermark_ok(struct zone *z, unsigned int order,
/* free_pages may go negative - that's OK */
long min = mark;
int o;
+#ifdef CONFIG_CMA
+ bool cma_is_subbed = false;
+#endif
free_pages -= (1 << order) - 1;
if (alloc_flags & ALLOC_HIGH)
@@ -1905,8 +1920,10 @@ static bool __zone_watermark_ok(struct zone *z, unsigned int order,
* unmovable/reclaimable allocation and they can suddenly
* vanish through CMA allocation
*/
- if (IS_ENABLED(CONFIG_CMA) && z->managed_cma_pages)
+ if (IS_ENABLED(CONFIG_CMA) && z->managed_cma_pages) {
free_pages -= zone_page_state(z, NR_FREE_CMA_PAGES);
+ cma_is_subbed = true;
+ }
if (free_pages <= min + z->lowmem_reserve[classzone_idx])
return false;
@@ -1914,6 +1931,13 @@ static bool __zone_watermark_ok(struct zone *z, unsigned int order,
/* At the next order, this order's pages become unavailable */
free_pages -= z->free_area[o].nr_free << o;
+ /* If CMA's page number of this order was substructed as part
+ of "zone_page_state(z, NR_FREE_CMA_PAGES)", subtracting
+ "z->free_area[o].nr_free << o" substructed CMA's page
+ number of this order again. So add it back. */
+ if (IS_ENABLED(CONFIG_CMA) && cma_is_subbed)
+ free_pages += z->free_area[o].cma_nr_free << o;
+
/* Require fewer higher order pages to be free */
min >>= 1;
@@ -4318,6 +4342,7 @@ static void __meminit zone_init_free_lists(struct zone *zone)
for_each_migratetype_order(order, t) {
INIT_LIST_HEAD(&zone->free_area[order].free_list[t]);
zone->free_area[order].nr_free = 0;
+ zone->free_area[order].cma_nr_free = 0;
}
}
@@ -6691,6 +6716,8 @@ __offline_isolated_pages(unsigned long start_pfn, unsigned long end_pfn)
list_del(&page->lru);
rmv_page_order(page);
zone->free_area[order].nr_free--;
+ if (is_migrate_cma(get_pageblock_migratetype(page)))
+ zone->free_area[order].cma_nr_free--;
for (i = 0; i < (1 << order); i++)
SetPageReserved((page+i));
pfn += (1 << order);
--
1.9.1
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