[PATCH RESEND 5/8] mm: memcontrol: teach uncharge_list to deal with kmem pages

[Vladimir Davydov]

Page table pages are batched-freed in release_pages on most
architectures. If we want to charge them to kmemcg (this is what is done
later in this series), we need to teach mem_cgroup_uncharge_list to
handle kmem pages.

Signed-off-by: Vladimir Davydov <vdavy...@virtuozzo.com>
---
 mm/memcontrol.c | 42 ++++++++++++++++++++++++------------------
 1 file changed, 24 insertions(+), 18 deletions(-)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 482b4a0c97e4..89a421ee4713 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -5432,15 +5432,18 @@ void mem_cgroup_cancel_charge(struct page *page, struct 
mem_cgroup *memcg,
 
 static void uncharge_batch(struct mem_cgroup *memcg, unsigned long pgpgout,
                           unsigned long nr_anon, unsigned long nr_file,
-                          unsigned long nr_huge, struct page *dummy_page)
+                          unsigned long nr_huge, unsigned long nr_kmem,
+                          struct page *dummy_page)
 {
-       unsigned long nr_pages = nr_anon + nr_file;
+       unsigned long nr_pages = nr_anon + nr_file + nr_kmem;
        unsigned long flags;
 
        if (!mem_cgroup_is_root(memcg)) {
                page_counter_uncharge(&memcg->memory, nr_pages);
                if (do_memsw_account())
                        page_counter_uncharge(&memcg->memsw, nr_pages);
+               if (!cgroup_subsys_on_dfl(memory_cgrp_subsys) && nr_kmem)
+                       page_counter_uncharge(&memcg->kmem, nr_kmem);
                memcg_oom_recover(memcg);
        }
 
@@ -5463,6 +5466,7 @@ static void uncharge_list(struct list_head *page_list)
        unsigned long nr_anon = 0;
        unsigned long nr_file = 0;
        unsigned long nr_huge = 0;
+       unsigned long nr_kmem = 0;
        unsigned long pgpgout = 0;
        struct list_head *next;
        struct page *page;
@@ -5473,8 +5477,6 @@ static void uncharge_list(struct list_head *page_list)
         */
        next = page_list->next;
        do {
-               unsigned int nr_pages = 1;
-
                page = list_entry(next, struct page, lru);
                next = page->lru.next;
 
@@ -5493,31 +5495,35 @@ static void uncharge_list(struct list_head *page_list)
                if (memcg != page->mem_cgroup) {
                        if (memcg) {
                                uncharge_batch(memcg, pgpgout, nr_anon, nr_file,
-                                              nr_huge, page);
-                               pgpgout = nr_anon = nr_file = nr_huge = 0;
+                                              nr_huge, nr_kmem, page);
+                               pgpgout = nr_anon = nr_file =
+                                       nr_huge = nr_kmem = 0;
                        }
                        memcg = page->mem_cgroup;
                }
 
-               if (PageTransHuge(page)) {
-                       nr_pages <<= compound_order(page);
-                       VM_BUG_ON_PAGE(!PageTransHuge(page), page);
-                       nr_huge += nr_pages;
-               }
+               if (!PageKmemcg(page)) {
+                       unsigned int nr_pages = 1;
 
-               if (PageAnon(page))
-                       nr_anon += nr_pages;
-               else
-                       nr_file += nr_pages;
+                       if (PageTransHuge(page)) {
+                               nr_pages <<= compound_order(page);
+                               VM_BUG_ON_PAGE(!PageTransHuge(page), page);
+                               nr_huge += nr_pages;
+                       }
+                       if (PageAnon(page))
+                               nr_anon += nr_pages;
+                       else
+                               nr_file += nr_pages;
+                       pgpgout++;
+               } else
+                       nr_kmem += 1 << compound_order(page);
 
                page->mem_cgroup = NULL;
-
-               pgpgout++;
        } while (next != page_list);
 
        if (memcg)
                uncharge_batch(memcg, pgpgout, nr_anon, nr_file,
-                              nr_huge, page);
+                              nr_huge, nr_kmem, page);
 }
 
 /**
-- 
2.1.4