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Fri, 09 Apr 2021 05:33:01 -0700 (PDT) Received: from localhost.localdomain ([139.177.225.243]) by smtp.gmail.com with ESMTPSA id t3sm2167785pfg.176.2021.04.09.05.32.55 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Fri, 09 Apr 2021 05:33:00 -0700 (PDT) From: Muchun Song To: guro@fb.com, hannes@cmpxchg.org, mhocko@kernel.org, akpm@linux-foundation.org, shakeelb@google.com, vdavydov.dev@gmail.com Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, duanxiongchun@bytedance.com, fam.zheng@bytedance.com, bsingharora@gmail.com, shy828301@gmail.com, alex.shi@linux.alibaba.com, Muchun Song Subject: [RFC PATCH v2 12/18] mm: thp: make deferred split queue lock safe when the LRU pages reparented Date: Fri, 9 Apr 2021 20:29:53 +0800 Message-Id: <20210409122959.82264-13-songmuchun@bytedance.com> X-Mailer: git-send-email 2.21.0 (Apple Git-122) In-Reply-To: <20210409122959.82264-1-songmuchun@bytedance.com> References: <20210409122959.82264-1-songmuchun@bytedance.com> MIME-Version: 1.0 X-Stat-Signature: 933y45ko4w6cfhccpw1tmhku6kf75jjc X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 5535380192DA Received-SPF: none (bytedance.com>: No applicable sender policy available) receiver=imf16; identity=mailfrom; envelope-from=""; helo=mail-pf1-f178.google.com; client-ip=209.85.210.178 X-HE-DKIM-Result: pass/pass X-HE-Tag: 1617971581-207390 Content-Transfer-Encoding: quoted-printable X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Similar to lruvec lock, we use the same approach to make the lock safe when the LRU pages reparented. Signed-off-by: Muchun Song --- mm/huge_memory.c | 23 +++++++++++++++++++++++ 1 file changed, 23 insertions(+) diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 275dbfc8b2ae..aa5d7b72d5fc 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -497,6 +497,8 @@ static struct deferred_split *lock_split_queue(struct= page *page) struct deferred_split *queue; struct mem_cgroup *memcg; =20 + rcu_read_lock(); +retry: memcg =3D page_memcg(compound_head(page)); if (memcg) queue =3D &memcg->deferred_split_queue; @@ -504,6 +506,17 @@ static struct deferred_split *lock_split_queue(struc= t page *page) queue =3D &NODE_DATA(page_to_nid(page))->deferred_split_queue; spin_lock(&queue->split_queue_lock); =20 + if (unlikely(memcg !=3D page_memcg(page))) { + spin_unlock(&queue->split_queue_lock); + goto retry; + } + + /* + * Preemption is disabled in the internal of spin_lock, which can serve + * as RCU read-side critical sections. + */ + rcu_read_unlock(); + return queue; } =20 @@ -513,6 +526,8 @@ static struct deferred_split *lock_split_queue_irqsav= e(struct page *page, struct deferred_split *queue; struct mem_cgroup *memcg; =20 + rcu_read_lock(); +retry: memcg =3D page_memcg(compound_head(page)); if (memcg) queue =3D &memcg->deferred_split_queue; @@ -520,6 +535,14 @@ static struct deferred_split *lock_split_queue_irqsa= ve(struct page *page, queue =3D &NODE_DATA(page_to_nid(page))->deferred_split_queue; spin_lock_irqsave(&queue->split_queue_lock, *flags); =20 + if (unlikely(memcg !=3D page_memcg(page))) { + spin_unlock_irqrestore(&queue->split_queue_lock, *flags); + goto retry; + } + + /* See the comments in lock_split_queue(). */ + rcu_read_unlock(); + return queue; } #else --=20 2.11.0