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DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1761660252; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=awA3itBKj19H7/d+bEsq6yy17boeItLnhliB54mswXw=; b=mQRNNpfrKBpzz1ab1nTDgyCoguSHCTkk95shXK3iNipGI04oEMEXi5IIHEPqlqy+SEmRpM qyRZZQYqvRsB5YE+THqhsZdE833GfIrCf6qfwNtQCy481oRQtt+89LTqZmnI4GWpd8q08w S9hcQ/U+3SEnqwhb2eichfz//vZJxFk= From: Qi Zheng To: hannes@cmpxchg.org, hughd@google.com, mhocko@suse.com, roman.gushchin@linux.dev, shakeel.butt@linux.dev, muchun.song@linux.dev, david@redhat.com, lorenzo.stoakes@oracle.com, ziy@nvidia.com, harry.yoo@oracle.com, imran.f.khan@oracle.com, kamalesh.babulal@oracle.com, axelrasmussen@google.com, yuanchu@google.com, weixugc@google.com, akpm@linux-foundation.org Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, Muchun Song , Nhat Pham , Chengming Zhou , Qi Zheng Subject: [PATCH v1 18/26] mm: zswap: prevent lruvec release in zswap_folio_swapin() Date: Tue, 28 Oct 2025 21:58:31 +0800 Message-ID: In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT X-Rspamd-Server: rspam05 X-Stat-Signature: mz7rcpezprsfmuji5d7fzd4jk8gq9a4g X-Rspam-User: X-Rspamd-Queue-Id: 799D040008 X-HE-Tag: 1761660254-760265 X-HE-Meta: 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 5UTRFYPA KgRtPRMIjvlVwSfR7CKDHYc8PEXDnwSjvU4ZMXz0BMqlX3q9kRM65suIYeWYIxXyFqWr1sIy+cQ8rnGBpmaWBX2AecYKkmRKyDYRHJCCFdyQUVeU5uDXa7P2QDd9ys+V98GNpJP2PuGf7kk4yxM95f18eeCf3+RnmLP73wKpxQvk2WEKruANjfG+Bi6WpxzKZKq0+3yUSMN2ahkvdf9L/gEzwDA== 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: List-Subscribe: List-Unsubscribe: From: Muchun Song In the near future, a folio will no longer pin its corresponding memory cgroup. So an lruvec returned by folio_lruvec() could be released without the rcu read lock or a reference to its memory cgroup. In the current patch, the rcu read lock is employed to safeguard against the release of the lruvec in zswap_folio_swapin(). This serves as a preparatory measure for the reparenting of the LRU pages. Signed-off-by: Muchun Song Acked-by: Nhat Pham Reviewed-by: Chengming Zhou Signed-off-by: Qi Zheng --- mm/zswap.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/mm/zswap.c b/mm/zswap.c index 5d0f8b13a958d..a341814468b95 100644 --- a/mm/zswap.c +++ b/mm/zswap.c @@ -664,8 +664,10 @@ void zswap_folio_swapin(struct folio *folio) struct lruvec *lruvec; if (folio) { + rcu_read_lock(); lruvec = folio_lruvec(folio); atomic_long_inc(&lruvec->zswap_lruvec_state.nr_disk_swapins); + rcu_read_unlock(); } } -- 2.20.1