[RFC PATCH 4/5] mm: rename and change semantics of nr_indirectly_reclaimable_bytes
From: Vlastimil Babka
Date: Thu May 24 2018 - 06:09:19 EST
The vmstat counter NR_INDIRECTLY_RECLAIMABLE_BYTES was introduced by commit
eb59254608bc ("mm: introduce NR_INDIRECTLY_RECLAIMABLE_BYTES") with the goal of
accounting objects that can be reclaimed, but cannot be allocated via a
SLAB_RECLAIM_ACCOUNT cache. This is now possible via kmalloc() with
__GFP_RECLAIMABLE flag, and the dcache external names user is converted.
The counter is however still useful for accounting direct page allocations
(i.e. not slab) with a shrinker, such as the ION page pool. So keep it, and:
- change granularity to pages to be more like other counters; sub-page
allocations should be able to use kmalloc
- rename the counter to NR_RECLAIMABLE
- expose the counter again in vmstat as "nr_reclaimable"; we can again remove
the check for not printing "hidden" counters
- make the counter include also SLAB_RECLAIM_ACCOUNT, so it covers all
shrinker-based (i.e. not page cache) reclaimable pages
Signed-off-by: Vlastimil Babka <vbabka@xxxxxxx>
---
drivers/staging/android/ion/ion_page_pool.c | 4 ++--
include/linux/mmzone.h | 2 +-
mm/page_alloc.c | 15 ++++-----------
mm/slab.c | 12 ++++++++----
mm/util.c | 16 +++++-----------
mm/vmstat.c | 6 +-----
6 files changed, 21 insertions(+), 34 deletions(-)
diff --git a/drivers/staging/android/ion/ion_page_pool.c b/drivers/staging/android/ion/ion_page_pool.c
index 9bc56eb48d2a..11e6e694f425 100644
--- a/drivers/staging/android/ion/ion_page_pool.c
+++ b/drivers/staging/android/ion/ion_page_pool.c
@@ -33,8 +33,8 @@ static void ion_page_pool_add(struct ion_page_pool *pool, struct page *page)
pool->low_count++;
}
- mod_node_page_state(page_pgdat(page), NR_INDIRECTLY_RECLAIMABLE_BYTES,
- (1 << (PAGE_SHIFT + pool->order)));
+ mod_node_page_state(page_pgdat(page), NR_RECLAIMABLE,
+ 1 << pool->order);
mutex_unlock(&pool->mutex);
}
diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index 32699b2dc52a..4343948f33e5 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -180,7 +180,7 @@ enum node_stat_item {
NR_VMSCAN_IMMEDIATE, /* Prioritise for reclaim when writeback ends */
NR_DIRTIED, /* page dirtyings since bootup */
NR_WRITTEN, /* page writings since bootup */
- NR_INDIRECTLY_RECLAIMABLE_BYTES, /* measured in bytes */
+ NR_RECLAIMABLE, /* all reclaimable pages, including slab */
NR_VM_NODE_STAT_ITEMS
};
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 249546393bd6..6f22fec0df54 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -4708,6 +4708,7 @@ long si_mem_available(void)
unsigned long pagecache;
unsigned long wmark_low = 0;
unsigned long pages[NR_LRU_LISTS];
+ unsigned long reclaimable;
struct zone *zone;
int lru;
@@ -4733,19 +4734,11 @@ long si_mem_available(void)
available += pagecache;
/*
- * Part of the reclaimable slab consists of items that are in use,
+ * Part of the reclaimable pages consists of items that are in use,
* and cannot be freed. Cap this estimate at the low watermark.
*/
- available += global_node_page_state(NR_SLAB_RECLAIMABLE) -
- min(global_node_page_state(NR_SLAB_RECLAIMABLE) / 2,
- wmark_low);
-
- /*
- * Part of the kernel memory, which can be released under memory
- * pressure.
- */
- available += global_node_page_state(NR_INDIRECTLY_RECLAIMABLE_BYTES) >>
- PAGE_SHIFT;
+ reclaimable = global_node_page_state(NR_RECLAIMABLE);
+ available += reclaimable - min(reclaimable / 2, wmark_low);
if (available < 0)
available = 0;
diff --git a/mm/slab.c b/mm/slab.c
index 4dd7d73a1972..a2a8c0802253 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -1420,10 +1420,12 @@ static struct page *kmem_getpages(struct kmem_cache *cachep, gfp_t flags,
}
nr_pages = (1 << cachep->gfporder);
- if (cachep->flags & SLAB_RECLAIM_ACCOUNT)
+ if (cachep->flags & SLAB_RECLAIM_ACCOUNT) {
mod_lruvec_page_state(page, NR_SLAB_RECLAIMABLE, nr_pages);
- else
+ mod_node_page_state(page_pgdat(page), NR_RECLAIMABLE, nr_pages);
+ } else {
mod_lruvec_page_state(page, NR_SLAB_UNRECLAIMABLE, nr_pages);
+ }
__SetPageSlab(page);
/* Record if ALLOC_NO_WATERMARKS was set when allocating the slab */
@@ -1441,10 +1443,12 @@ static void kmem_freepages(struct kmem_cache *cachep, struct page *page)
int order = cachep->gfporder;
unsigned long nr_freed = (1 << order);
- if (cachep->flags & SLAB_RECLAIM_ACCOUNT)
+ if (cachep->flags & SLAB_RECLAIM_ACCOUNT) {
mod_lruvec_page_state(page, NR_SLAB_RECLAIMABLE, -nr_freed);
- else
+ mod_node_page_state(page_pgdat(page), NR_RECLAIMABLE, -nr_freed);
+ } else {
mod_lruvec_page_state(page, NR_SLAB_UNRECLAIMABLE, -nr_freed);
+ }
BUG_ON(!PageSlab(page));
__ClearPageSlabPfmemalloc(page);
diff --git a/mm/util.c b/mm/util.c
index 98180a994895..3ffd92a9778a 100644
--- a/mm/util.c
+++ b/mm/util.c
@@ -662,19 +662,13 @@ int __vm_enough_memory(struct mm_struct *mm, long pages, int cap_sys_admin)
free += get_nr_swap_pages();
/*
- * Any slabs which are created with the
+ * Pages accounted as reclaimable.
+ * This includes any slabs which are created with the
* SLAB_RECLAIM_ACCOUNT flag claim to have contents
- * which are reclaimable, under pressure. The dentry
- * cache and most inode caches should fall into this
+ * which are reclaimable, under pressure. The dentry
+ * cache and most inode caches should fall into this.
*/
- free += global_node_page_state(NR_SLAB_RECLAIMABLE);
-
- /*
- * Part of the kernel memory, which can be released
- * under memory pressure.
- */
- free += global_node_page_state(
- NR_INDIRECTLY_RECLAIMABLE_BYTES) >> PAGE_SHIFT;
+ free += global_node_page_state(NR_RECLAIMABLE);
/*
* Leave reserved pages. The pages are not for anonymous pages.
diff --git a/mm/vmstat.c b/mm/vmstat.c
index 75eda9c2b260..21d571da9d5a 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -1161,7 +1161,7 @@ const char * const vmstat_text[] = {
"nr_vmscan_immediate_reclaim",
"nr_dirtied",
"nr_written",
- "", /* nr_indirectly_reclaimable */
+ "nr_reclaimable",
/* enum writeback_stat_item counters */
"nr_dirty_threshold",
@@ -1704,10 +1704,6 @@ static int vmstat_show(struct seq_file *m, void *arg)
unsigned long *l = arg;
unsigned long off = l - (unsigned long *)m->private;
- /* Skip hidden vmstat items. */
- if (*vmstat_text[off] == '\0')
- return 0;
-
seq_puts(m, vmstat_text[off]);
seq_put_decimal_ull(m, " ", *l);
seq_putc(m, '\n');
--
2.17.0