[PATCH v2 8/8] page_frag: Account allocations

[Matthew Wilcox]

From: Matthew Wilcox <mawil...@microsoft.com>

Note the number of pages currently used in page_frag allocations.
This may help diagnose leaks in page_frag users.

Signed-off-by: Matthew Wilcox <mawil...@microsoft.com>
---
 include/linux/mmzone.h |  3 ++-
 mm/page_alloc.c        | 10 +++++++---
 2 files changed, 9 insertions(+), 4 deletions(-)

diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index 7522a6987595..ed6be33dcc7a 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -139,10 +139,10 @@ enum zone_stat_item {
        NR_ZONE_ACTIVE_FILE,
        NR_ZONE_UNEVICTABLE,
        NR_ZONE_WRITE_PENDING,  /* Count of dirty, writeback and unstable pages 
*/
+       /* Second 128 byte cacheline */
        NR_MLOCK,               /* mlock()ed pages found and moved off LRU */
        NR_PAGETABLE,           /* used for pagetables */
        NR_KERNEL_STACK_KB,     /* measured in KiB */
-       /* Second 128 byte cacheline */
        NR_BOUNCE,
 #if IS_ENABLED(CONFIG_ZSMALLOC)
        NR_ZSPAGES,             /* allocated in zsmalloc */
@@ -175,6 +175,7 @@ enum node_stat_item {
        NR_SHMEM_THPS,
        NR_SHMEM_PMDMAPPED,
        NR_ANON_THPS,
+       NR_PAGE_FRAG,
        NR_UNSTABLE_NFS,        /* NFS unstable pages */
        NR_VMSCAN_WRITE,
        NR_VMSCAN_IMMEDIATE,    /* Prioritise for reclaim when writeback ends */
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index b9beafa5d2a5..5a9441b46604 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -4382,6 +4382,7 @@ static void *__page_frag_cache_refill(struct 
page_frag_cache *pfc,
                return NULL;
        }
 
+       inc_node_page_state(page, NR_PAGE_FRAG);
        /* Using atomic_set() would break get_page_unless_zero() users. */
        page_ref_add(page, size - 1);
 reset:
@@ -4460,8 +4461,10 @@ void page_frag_free(void *addr)
 {
        struct page *page = virt_to_head_page(addr);
 
-       if (unlikely(put_page_testzero(page)))
+       if (unlikely(put_page_testzero(page))) {
+               dec_node_page_state(page, NR_PAGE_FRAG);
                __free_pages_ok(page, compound_order(page));
+       }
 }
 EXPORT_SYMBOL(page_frag_free);
 
@@ -4769,7 +4772,7 @@ void show_free_areas(unsigned int filter, nodemask_t 
*nodemask)
                " unevictable:%lu dirty:%lu writeback:%lu unstable:%lu\n"
                " slab_reclaimable:%lu slab_unreclaimable:%lu\n"
                " mapped:%lu shmem:%lu pagetables:%lu bounce:%lu\n"
-               " free:%lu free_pcp:%lu free_cma:%lu\n",
+               " free:%lu free_pcp:%lu free_cma:%lu page_frag:%lu\n",
                global_node_page_state(NR_ACTIVE_ANON),
                global_node_page_state(NR_INACTIVE_ANON),
                global_node_page_state(NR_ISOLATED_ANON),
@@ -4788,7 +4791,8 @@ void show_free_areas(unsigned int filter, nodemask_t 
*nodemask)
                global_zone_page_state(NR_BOUNCE),
                global_zone_page_state(NR_FREE_PAGES),
                free_pcp,
-               global_zone_page_state(NR_FREE_CMA_PAGES));
+               global_zone_page_state(NR_FREE_CMA_PAGES),
+               global_node_page_state(NR_PAGE_FRAG));
 
        for_each_online_pgdat(pgdat) {
                if (show_mem_node_skip(filter, pgdat->node_id, nodemask))
-- 
2.16.2