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Subject[PATCH v3 5/7] mm: rename and change semantics of nr_indirectly_reclaimable_bytes
Date
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_KERNEL_MISC_RECLAIMABLE
- expose the counter again in vmstat as "nr_kernel_misc_reclaimable"; we can
again remove the check for not printing "hidden" counters

Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Vijayanand Jitta <vjitta@codeaurora.org>
Cc: Laura Abbott <labbott@redhat.com>
Cc: Sumit Semwal <sumit.semwal@linaro.org>
---
drivers/staging/android/ion/ion_page_pool.c | 8 ++++----
include/linux/mmzone.h | 2 +-
mm/page_alloc.c | 19 +++++++------------
mm/util.c | 3 +--
mm/vmstat.c | 6 +-----
5 files changed, 14 insertions(+), 24 deletions(-)

diff --git a/drivers/staging/android/ion/ion_page_pool.c b/drivers/staging/android/ion/ion_page_pool.c
index 9bc56eb48d2a..0d2a95957ee8 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_KERNEL_MISC_RECLAIMABLE,
+ 1 << pool->order);
mutex_unlock(&pool->mutex);
}

@@ -53,8 +53,8 @@ static struct page *ion_page_pool_remove(struct ion_page_pool *pool, bool high)
}

list_del(&page->lru);
- mod_node_page_state(page_pgdat(page), NR_INDIRECTLY_RECLAIMABLE_BYTES,
- -(1 << (PAGE_SHIFT + pool->order)));
+ mod_node_page_state(page_pgdat(page), NR_KERNEL_MISC_RECLAIMABLE,
+ -(1 << pool->order));
return page;
}

diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index 32699b2dc52a..c2f6bc4c9e8a 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_KERNEL_MISC_RECLAIMABLE, /* reclaimable non-slab kernel pages */
NR_VM_NODE_STAT_ITEMS
};

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 5d800d61ddb7..91f75bf4404d 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -4704,6 +4704,7 @@ 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;

@@ -4729,19 +4730,13 @@ long si_mem_available(void)
available += pagecache;

/*
- * Part of the reclaimable slab consists of items that are in use,
- * and cannot be freed. Cap this estimate at the low watermark.
+ * Part of the reclaimable slab and other kernel memory 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_SLAB_RECLAIMABLE) +
+ global_node_page_state(NR_KERNEL_MISC_RECLAIMABLE);
+ available += reclaimable - min(reclaimable / 2, wmark_low);

if (available < 0)
available = 0;
diff --git a/mm/util.c b/mm/util.c
index 3351659200e6..891f0654e7b5 100644
--- a/mm/util.c
+++ b/mm/util.c
@@ -675,8 +675,7 @@ int __vm_enough_memory(struct mm_struct *mm, long pages, int cap_sys_admin)
* 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_KERNEL_MISC_RECLAIMABLE);

/*
* Leave reserved pages. The pages are not for anonymous pages.
diff --git a/mm/vmstat.c b/mm/vmstat.c
index 8ba0870ecddd..c5e52f94ba5f 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_kernel_misc_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');
--
2.18.0
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