The patch titled
Subject: CMA: fix CMA's page number is substructed twice in __zone_watermark_ok
has been removed from the -mm tree. Its filename was
cma-fix-cmas-page-number-is-substructed-twice-in-__zone_watermark_ok.patch
This patch was dropped because an updated version will be merged
------------------------------------------------------
From: Hui Zhu <zhuhui@xxxxxxxxxx>
Subject: CMA: fix CMA's page number is substructed twice in __zone_watermark_ok
The original of this patch [1] is used to fix the issue in Joonsoo's CMA
patch "CMA: always treat free cma pages as non-free on watermark checking"
[2].
Joonsoo reminded me that this issue affect current kernel too. So made a
new one for upstream.
__zone_watermark_ok() subtracts CMA pages number from free_pages if system
allocation can't use CMA areas:
/* If allocation can't use CMA areas don't use free CMA pages */
if (!(alloc_flags & ALLOC_CMA))
free_cma = 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 subtracted twice. This bug will make
__zone_watermark_ok return false too frequently.
This patch adds cma_free_area to struct free_area to record the number of
CMA pages. And add it back in the order loop to handle the subtraction
twice issue.
[1] https://lkml.org/lkml/2014/12/25/43
[2] https://lkml.org/lkml/2014/5/28/110
[akpm@xxxxxxxxxxxxxxxxxxxx: fix comment layout and spelling]
Signed-off-by: Hui Zhu <zhuhui@xxxxxxxxxx>
Signed-off-by: Weixing Liu <liuweixing@xxxxxxxxxx>
Cc: Mel Gorman <mgorman@xxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Rik van Riel <riel@xxxxxxxxxx>
Cc: Vlastimil Babka <vbabka@xxxxxxx>
Cc: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
Cc: Yasuaki Ishimatsu <isimatu.yasuaki@xxxxxxxxxxxxxx>
Cc: David Rientjes <rientjes@xxxxxxxxxx>
Cc: Sasha Levin <sasha.levin@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/mmzone.h | 3 +++
mm/page_alloc.c | 24 ++++++++++++++++++++++++
2 files changed, 27 insertions(+)
diff -puN include/linux/mmzone.h~cma-fix-cmas-page-number-is-substructed-twice-in-__zone_watermark_ok include/linux/mmzone.h
--- a/include/linux/mmzone.h~cma-fix-cmas-page-number-is-substructed-twice-in-__zone_watermark_ok
+++ a/include/linux/mmzone.h
@@ -92,6 +92,9 @@ static inline int get_pfnblock_migratety
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 -puN mm/page_alloc.c~cma-fix-cmas-page-number-is-substructed-twice-in-__zone_watermark_ok mm/page_alloc.c
--- a/mm/page_alloc.c~cma-fix-cmas-page-number-is-substructed-twice-in-__zone_watermark_ok
+++ a/mm/page_alloc.c
@@ -650,6 +650,8 @@ static inline void __free_one_page(struc
} 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(struc
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)
@@ -937,6 +941,8 @@ static inline void expand(struct zone *z
}
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);
}
}
@@ -1020,6 +1026,8 @@ struct page *__rmqueue_smallest(struct z
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;
@@ -1208,6 +1216,8 @@ __rmqueue_fallback(struct zone *zone, un
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,
@@ -1597,6 +1607,8 @@ int __isolate_free_page(struct page *pag
/* 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 */
@@ -1827,6 +1839,15 @@ static bool __zone_watermark_ok(struct z
/* 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 substracted as part
+ * of "zone_page_state(z, NR_FREE_CMA_PAGES)", subtracting
+ * "z->free_area[o].nr_free << o" subtracted CMA's page number
+ * of this order again. So add it back.
+ */
+ if (IS_ENABLED(CONFIG_CMA) && free_cma)
+ free_pages += z->free_area[o].cma_nr_free << o;
+
/* Require fewer higher order pages to be free */
min >>= 1;
@@ -4226,6 +4247,7 @@ static void __meminit zone_init_free_lis
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;
}
}
@@ -6598,6 +6620,8 @@ __offline_isolated_pages(unsigned long s
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);
_
Patches currently in -mm which might be from zhuhui@xxxxxxxxxx are
cma-fix-cmas-page-number-is-substructed-twice-in-__zone_watermark_ok-fix-2.patch
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