The reclaim_pages MADV_PAGEOUT uses needs to return the number of
pages paged-out successfully, not only the number of reclaimed pages
in the operation because those pages paged-out successfully will be
reclaimed easily at the memory pressure due to asynchronous writeback
rotation(i.e., PG_reclaim with folio_rotate_reclaimable).
This patch renames the reclaim_pages with paging_out(with hope that
it's clear from operation point of view) and then adds a additional
stat in reclaim_stat to represent the number of paged-out but kept
in the memory for rotation on writeback completion.
With that stat, madvise_pageout can know how many pages were paged-out
successfully as well as reclaimed. The return value will be used for
statistics in next patch.
Signed-off-by: Minchan Kim <minchan@xxxxxxxxxx>
---
include/linux/swap.h | 2 +-
include/linux/vmstat.h | 1 +
mm/damon/paddr.c | 2 +-
mm/madvise.c | 4 ++--
mm/vmscan.c | 31 ++++++++++++++++++++++---------
5 files changed, 27 insertions(+), 13 deletions(-)
diff --git a/include/linux/swap.h b/include/linux/swap.h
index a18cf4b7c724..0ada46b595cd 100644
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -435,7 +435,7 @@ extern unsigned long shrink_all_memory(unsigned long nr_pages);
extern int vm_swappiness;
long remove_mapping(struct address_space *mapping, struct folio *folio);
-extern unsigned long reclaim_pages(struct list_head *page_list);
+extern unsigned int paging_out(struct list_head *page_list);
#ifdef CONFIG_NUMA
extern int node_reclaim_mode;
extern int sysctl_min_unmapped_ratio;
diff --git a/include/linux/vmstat.h b/include/linux/vmstat.h
index 19cf5b6892ce..cda903a8fa6e 100644
--- a/include/linux/vmstat.h
+++ b/include/linux/vmstat.h
@@ -28,6 +28,7 @@ struct reclaim_stat {
unsigned nr_writeback;
unsigned nr_immediate;
unsigned nr_pageout;
+ unsigned nr_pageout_keep;
unsigned nr_activate[ANON_AND_FILE];
unsigned nr_ref_keep;
unsigned nr_unmap_fail;
diff --git a/mm/damon/paddr.c b/mm/damon/paddr.c
index e1a4315c4be6..be2a731d3459 100644
--- a/mm/damon/paddr.c
+++ b/mm/damon/paddr.c
@@ -226,7 +226,7 @@ static unsigned long damon_pa_pageout(struct damon_region *r)
put_page(page);
}
}
- applied = reclaim_pages(&page_list);
+ applied = paging_out(&page_list);
cond_resched();
return applied * PAGE_SIZE;
}
diff --git a/mm/madvise.c b/mm/madvise.c
index c7105ec6d08c..a4a03054ab6b 100644
--- a/mm/madvise.c
+++ b/mm/madvise.c
@@ -400,7 +400,7 @@ static int madvise_cold_or_pageout_pte_range(pmd_t *pmd,
huge_unlock:
spin_unlock(ptl);
if (pageout)
- reclaim_pages(&page_list);
+ paging_out(&page_list);
return 0;
}
@@ -491,7 +491,7 @@ static int madvise_cold_or_pageout_pte_range(pmd_t *pmd,
arch_leave_lazy_mmu_mode();
pte_unmap_unlock(orig_pte, ptl);
if (pageout)
- reclaim_pages(&page_list);
+ paging_out(&page_list);
cond_resched();
return 0;
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 04d8b88e5216..579a7ebbe24a 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1933,6 +1933,7 @@ static unsigned int shrink_folio_list(struct list_head *folio_list,
goto activate_locked;
case PAGE_SUCCESS:
stat->nr_pageout += nr_pages;
+ stat->nr_pageout_keep += nr_pages;
if (folio_test_writeback(folio))
goto keep;
@@ -1948,6 +1949,8 @@ static unsigned int shrink_folio_list(struct list_head *folio_list,
if (folio_test_dirty(folio) ||
folio_test_writeback(folio))
goto keep_locked;
+
+ stat->nr_pageout_keep -= nr_pages;
mapping = folio_mapping(folio);
fallthrough;
case PAGE_CLEAN:
@@ -2646,9 +2649,9 @@ static void shrink_active_list(unsigned long nr_to_scan,
}
static unsigned int reclaim_folio_list(struct list_head *folio_list,
- struct pglist_data *pgdat)
+ struct pglist_data *pgdat,
+ struct reclaim_stat *stat)
{
- struct reclaim_stat dummy_stat;
unsigned int nr_reclaimed;
struct folio *folio;
struct scan_control sc = {
@@ -2659,7 +2662,7 @@ static unsigned int reclaim_folio_list(struct list_head *folio_list,
.no_demotion = 1,
};
- nr_reclaimed = shrink_folio_list(folio_list, pgdat, &sc, &dummy_stat, false);
+ nr_reclaimed = shrink_folio_list(folio_list, pgdat, &sc, stat, false);
while (!list_empty(folio_list)) {
folio = lru_to_folio(folio_list);
list_del(&folio->lru);
@@ -2669,15 +2672,23 @@ static unsigned int reclaim_folio_list(struct list_head *folio_list,
return nr_reclaimed;
}
-unsigned long reclaim_pages(struct list_head *folio_list)
+/*
+ * paging_out - reclaim clean pages and write dirty pages into storage
+ * @folio_list: pages for paging out
+ *
+ * paging_out() writes dirty pages to backing storage and/or reclaim
+ * clean pages from memory. Returns the number of written/reclaimed pages.
+ */
+unsigned int paging_out(struct list_head *folio_list)
{
int nid;
- unsigned int nr_reclaimed = 0;
+ unsigned int nr_pageout = 0;
LIST_HEAD(node_folio_list);
unsigned int noreclaim_flag;
+ struct reclaim_stat stat;
if (list_empty(folio_list))
- return nr_reclaimed;
+ return nr_pageout;
noreclaim_flag = memalloc_noreclaim_save();
@@ -2691,15 +2702,17 @@ unsigned long reclaim_pages(struct list_head *folio_list)
continue;
}
- nr_reclaimed += reclaim_folio_list(&node_folio_list, NODE_DATA(nid));
+ nr_pageout += reclaim_folio_list(&node_folio_list, NODE_DATA(nid), &stat);
+ nr_pageout += stat.nr_pageout_keep;
nid = folio_nid(lru_to_folio(folio_list));
} while (!list_empty(folio_list));
- nr_reclaimed += reclaim_folio_list(&node_folio_list, NODE_DATA(nid));
+ nr_pageout += reclaim_folio_list(&node_folio_list, NODE_DATA(nid), &stat);
+ nr_pageout += stat.nr_pageout_keep;
memalloc_noreclaim_restore(noreclaim_flag);
- return nr_reclaimed;
+ return nr_pageout;
}
static unsigned long shrink_list(enum lru_list lru, unsigned long nr_to_scan,
--
2.39.0.314.g84b9a713c41-goog
