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AJvYcCWi4SxKd4hgTPkw9R02+cP4+S1ZRcWLys4QiyHPpIxH39LHf7XEPu5YZjw//6NWndBX3HaDswq8lw==@kvack.org X-Gm-Message-State: AOJu0Yy2kK3aP7fZ9sQVXvVTkhAG9tjLWOH/1E+GmlHpX2v1sxYpBO5J BFK8cb61JoodCBPevsS0yXA0/zOKiqIkrcm8Qxncvmdbeau/hgOdERAn5TzOoyLYzfNphk1ZDOE fkRv2XZ3PzGTpGzyXTA5ulZ/EFTA= X-Gm-Gg: ASbGncv7DtaEAhMY/QrnUgXH6pSV0nJ9+uqbq2g5nB1yFpU/kkM5tXQx8mbwc57fneL CEc0DThLJNk4qmbiTCExlZbDablGL30zja+Dd/ha/7Q/GwiPVGh3QGYndcFlGKxNgJ/fiAgCvWS gs1X2jsMRDIxUhlDrzfStXXbgZ/RSKQa6Z/A== X-Google-Smtp-Source: AGHT+IFsg3WsedqYYClWbiPfH/kZJGoZhJCSZlGHr/KP3lAIsVoxNjt85IcMoa3Fs4WaZYg3jHMvlVYzOXx7ANmPxAM= X-Received: by 2002:ad4:5b83:0:b0:6e8:fa7a:14ab with SMTP id 6a1803df08f44-6f2b2f22f6amr87091256d6.6.1744911556885; Thu, 17 Apr 2025 10:39:16 -0700 (PDT) MIME-Version: 1.0 References: <20250415024532.26632-1-songmuchun@bytedance.com> <20250415024532.26632-22-songmuchun@bytedance.com> In-Reply-To: <20250415024532.26632-22-songmuchun@bytedance.com> From: Nhat Pham Date: Thu, 17 Apr 2025 10:39:05 -0700 X-Gm-Features: ATxdqUHfTz5BvLkk64iIoNn6d0Ol7xPi_VzpoY4ezJknMWiDhkMbdgsF-jH6xBs Message-ID: Subject: Re: [PATCH RFC 21/28] mm: zswap: prevent lruvec release in zswap_folio_swapin() To: Muchun Song Cc: hannes@cmpxchg.org, mhocko@kernel.org, roman.gushchin@linux.dev, shakeel.butt@linux.dev, muchun.song@linux.dev, akpm@linux-foundation.org, david@fromorbit.com, zhengqi.arch@bytedance.com, yosry.ahmed@linux.dev, chengming.zhou@linux.dev, linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, linux-mm@kvack.org, hamzamahfooz@linux.microsoft.com, apais@linux.microsoft.com Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Queue-Id: F3B1640011 X-Stat-Signature: zyxnwcf34go63w9hhaa77a8k5hi91n8q X-Rspam-User: X-Rspamd-Server: rspam08 X-HE-Tag: 1744911557-974373 X-HE-Meta: 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 W2tDyB3j Exw+o7BovFrOvQuakO8ve3/gly8v76Uy9xKH/HDH+H033ZGeCufdzcbFEvYRrxQ82ORRqIJTg8IvBD1IEi0Odsu7uSxJpI+l1DHJ6evfQNymZLrvsuSMQMxk/MLXK9wet7lQwOOH44FzHqxmJSLx3Cf0IccP+J8r0m5t/eTDnHWxpCbRm1XtokRohAkp+Ul+4eaijyJPdHP8lx367aX5d6IVn6BSEexjtvBAJJw4iy21a/Wpoo2VOVJ6G3NsIS7njBKGDqLxfPsCCKWyBEl+eOPwROduZ7K/UMKqEYfBaQozrnPQs57Mztp7VvPXzlzVhhX/1V6PuUtK1P9n0+DsIffSNUVUyqPZpJ2xkb+Vj578wTU/jHqq4ukAtjWfCKW1ivc9KSFzutQa1qnXGeRKCSjy6mQxCmDVO57tG X-Bogosity: Ham, tests=bogofilter, spamicity=0.000972, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon, Apr 14, 2025 at 7:47=E2=80=AFPM Muchun Song wrote: > > 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 No objections from my end. AFAICT, wrapping this in rcu should not break things, and we're in the slow path (disk swapping) anyway, so should not be a problem. Anyway: Acked-by: Nhat Pham