[Devel] [PATCH RHEL COMMIT] mm: memcontrol: add swapin/out stats

[Konstantin Khorenko]

The commit is pushed to "branch-rh9-5.14.vz9.1.x-ovz" and will appear at https://src.openvz.org/scm/ovz/vzkernel.git
after ark-5.14
------>
commit 710dffc0dc7571cef59e39b3d4e4d7910f299e98
Author: Vladimir Davydov <vdavydov.dev at gmail.com>
Date:   Thu Sep 30 17:44:03 2021 +0300

    mm: memcontrol: add swapin/out stats
    
    This patch adds pswpin and pswpout fields to memory.stat file. These
    fields show the number of pages swapped in and out respectively for the
    given memory cgroup. We assume a page was swapped in/out even if there
    were no actual io (frontswap).
    
    https://jira.sw.ru/browse/PSBM-46104
    
    Signed-off-by: Vladimir Davydov <vdavydov at virtuozzo.com>
    Signed-off-by: Andrey Ryabinin <aryabinin at virtuozzo.com>
    
    Rebase to RHEL8.3 kernel-4.18.0-240.1.1.el8_3 notes:
    khorenko@: fixed mem_cgroup_swapout() to charge "nr_entries", not always
    1 page.
    
    Signed-off-by: Konstantin Khorenko <khorenko at virtuozzo.com>
    
    (cherry-picked from vz8 commit 09af291ddfd8 ("mm: memcontrol: add
    swapin/out stats"))
    
    Signed-off-by: Nikita Yushchenko <nikita.yushchenko at virtuozzo.com>
---
 mm/memcontrol.c | 3 +++
 mm/page_io.c    | 5 ++++-
 mm/vmstat.c     | 2 ++
 3 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 47384b7fce0a..65dec706430d 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -4118,6 +4118,8 @@ static const unsigned int memcg1_events[] = {
 	PGPGOUT,
 	PGFAULT,
 	PGMAJFAULT,
+	PSWPIN,
+	PSWPOUT,
 };
 
 static int memcg_stat_show(struct seq_file *m, void *v)
@@ -7408,6 +7410,7 @@ void mem_cgroup_swapout(struct page *page, swp_entry_t entry)
 				   nr_entries);
 	VM_BUG_ON_PAGE(oldid, page);
 	mod_memcg_state(swap_memcg, MEMCG_SWAP, nr_entries);
+	__count_memcg_events(swap_memcg, PSWPOUT, nr_entries);
 
 	page->memcg_data = 0;
 
diff --git a/mm/page_io.c b/mm/page_io.c
index c493ce9ebcf5..ea3ba397b33f 100644
--- a/mm/page_io.c
+++ b/mm/page_io.c
@@ -384,8 +384,10 @@ int swap_readpage(struct page *page, bool synchronous)
 		struct address_space *mapping = swap_file->f_mapping;
 
 		ret = mapping->a_ops->readpage(swap_file, page);
-		if (!ret)
+		if (!ret) {
+			count_memcg_page_event(page, PSWPIN);
 			count_vm_event(PSWPIN);
+		}
 		goto out;
 	}
 
@@ -397,6 +399,7 @@ int swap_readpage(struct page *page, bool synchronous)
 				unlock_page(page);
 			}
 
+			count_memcg_page_event(page, PSWPIN);
 			count_vm_event(PSWPIN);
 			goto out;
 		}
diff --git a/mm/vmstat.c b/mm/vmstat.c
index 44ce039d19c6..0ed75620f8f2 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -1211,6 +1211,8 @@ const char * const vmstat_text[] = {
 
 	"pgfault",
 	"pgmajfault",
+	"pswpin",
+	"pswpout",
 	"pglazyfreed",
 
 	"pgrefill",