linux-kernel - [RFC PATCH 5/8] memcg: recharge folios when accessed or dirtied

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Date:   Thu, 20 Jul 2023 07:08:22 +0000
From:   Yosry Ahmed <yosryahmed@...gle.com>
To:     Andrew Morton <akpm@...ux-foundation.org>,
        Johannes Weiner <hannes@...xchg.org>,
        Michal Hocko <mhocko@...nel.org>,
        Roman Gushchin <roman.gushchin@...ux.dev>,
        Shakeel Butt <shakeelb@...gle.com>
Cc:     Muchun Song <muchun.song@...ux.dev>,
        "Matthew Wilcox (Oracle)" <willy@...radead.org>,
        Tejun Heo <tj@...nel.org>, Zefan Li <lizefan.x@...edance.com>,
        Yu Zhao <yuzhao@...gle.com>,
        Luis Chamberlain <mcgrof@...nel.org>,
        Kees Cook <keescook@...omium.org>,
        Iurii Zaikin <yzaikin@...gle.com>,
        "T.J. Mercier" <tjmercier@...gle.com>,
        Greg Thelen <gthelen@...gle.com>, linux-kernel@...r.kernel.org,
        linux-mm@...ck.org, cgroups@...r.kernel.org,
        Yosry Ahmed <yosryahmed@...gle.com>
Subject: [RFC PATCH 5/8] memcg: recharge folios when accessed or dirtied

The previous patch provided support for deferred recharging of folios
when their memcgs go offline. This patch adds recharging hooks to
folio_mark_accessed() and folio_mark_dirty().
This should cover a variety of code paths where folios are accessed by
userspace.

The hook, folio_memcg_deferred_recharge() only checks if the folio is
charged to an offline memcg in the common fast path (i.e checks
folio->memcg_data). If yes, an asynchronous worker is queued to do the
actual work.

Signed-off-by: Yosry Ahmed <yosryahmed@...gle.com>
---
 mm/page-writeback.c | 2 ++
 mm/swap.c           | 2 ++
 2 files changed, 4 insertions(+)

diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index d3f42009bb70..a644530d98c7 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -2785,6 +2785,8 @@ bool folio_mark_dirty(struct folio *folio)
 {
 	struct address_space *mapping = folio_mapping(folio);
 
+	folio_memcg_deferred_recharge(folio);
+
 	if (likely(mapping)) {
 		/*
 		 * readahead/folio_deactivate could remain
diff --git a/mm/swap.c b/mm/swap.c
index cd8f0150ba3a..296c0b87c967 100644
--- a/mm/swap.c
+++ b/mm/swap.c
@@ -457,6 +457,8 @@ static void folio_inc_refs(struct folio *folio)
  */
 void folio_mark_accessed(struct folio *folio)
 {
+	folio_memcg_deferred_recharge(folio);
+
 	if (lru_gen_enabled()) {
 		folio_inc_refs(folio);
 		return;
-- 
2.41.0.255.g8b1d071c50-goog