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AJvYcCUZxPHbQmgN5Q3NbDNFnHqSOtyXeKHlc3CrA0/RMZJIduSnQZbF1EN79EjWypkwRBYhlHeEKAwaeHmNF1XxpZ62S3U= X-Gm-Message-State: AOJu0YwuoE3Kn+UKB398fMAni/7wF1sDnqxuuUW9NM6RCG0WpBFtHpRn 7xPAHO7Z55rpyopXXA/1QXm7s9fcOLkXHAJnWSTLFn8EoPBSnjmrpydvLb4C+bEPh6oI1LZwLmc ozK12lS6+tKE/m7sUKvDmRMyzH5U= X-Google-Smtp-Source: AGHT+IEl/qD7wLHTnMv7KvwlqOpK4Lk/pt/aps8dtOgZTCgEB2C8QGUtwEFpn7vAyw97G0Q2OuV6++2J5BPLyeuqWD0= X-Received: by 2002:a05:6214:1253:b0:6b5:dfc2:6699 with SMTP id 6a1803df08f44-6b98ed24a83mr8416d6.5.1721750116121; Tue, 23 Jul 2024 08:55:16 -0700 (PDT) MIME-Version: 1.0 References: <20240720044127.508042-1-flintglass@gmail.com> <20240720044127.508042-2-flintglass@gmail.com> In-Reply-To: From: Nhat Pham Date: Tue, 23 Jul 2024 08:55:05 -0700 Message-ID: Subject: Re: [PATCH v3 1/2] mm: zswap: fix global shrinker memcg iteration To: Takero Funaki Cc: Johannes Weiner , Yosry Ahmed , Chengming Zhou , Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 2D0E0A001A X-Stat-Signature: dtu19imqehfoz6f5biap1ztzbsosrkd8 X-Rspam-User: X-HE-Tag: 1721750116-808819 X-HE-Meta: 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 3gH8LLkI g7SbANFkdBLS90J+AvVj8sjnIBqtXShHSi9e+jqBCUqtQOCn9jVbm+5XooXsnPCg27zgXnQcqPQ6GhBDb/zLUWMYDZLedcCRYudkFJDEUab6IW1o40QSA5F3+5LqEF3oaqNaXMhVxPcPUXMYmb3zyMee9V9+hFwxIkpIGVq3Tw9C9LRgg/eMCm2DZd0O+iZ17c+poBj49DS6ca9nDFut67OmSqAvB51K9B7aDwPKFJyyFoQZ1/+2N1/dxQ0GcSM5l+eugo15m7AUcuQq1blzVptR+i0MUYBnBYzzJiFrQFW66ilywqJ/u2bg/C8it903f0FwChyQaceUR8G1ZT31aUchDxJJVTZEm68NM X-Bogosity: Ham, tests=bogofilter, spamicity=0.000009, 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 Tue, Jul 23, 2024 at 8:35=E2=80=AFAM Takero Funaki wrote: > > 2024=E5=B9=B47=E6=9C=8823=E6=97=A5(=E7=81=AB) 6:39 Nhat Pham : > > > > On Fri, Jul 19, 2024 at 9:41=E2=80=AFPM Takero Funaki wrote: > > > > > > This patch fixes an issue where the zswap global shrinker stopped > > > iterating through the memcg tree. > > > > > > The problem was that shrink_worker() would stop iterating when a memc= g > > > was being offlined and restart from the tree root. Now, it properly > > > handles the offline memcg and continues shrinking with the next memcg= . > > > > > > To avoid holding refcount of offline memcg encountered during the mem= cg > > > tree walking, shrink_worker() must continue iterating to release the > > > offline memcg to ensure the next memcg stored in the cursor is online= . > > > > > > The offline memcg cleaner has also been changed to avoid the same iss= ue. > > > When the next memcg of the offlined memcg is also offline, the refcou= nt > > > stored in the iteration cursor was held until the next shrink_worker(= ) > > > run. The cleaner must release the offline memcg recursively. > > > > > > Fixes: a65b0e7607cc ("zswap: make shrinking memcg-aware") > > > Signed-off-by: Takero Funaki > > Hmm LGTM for the most part - a couple nits > > [...] > > > + zswap_next_shrink =3D mem_cgroup_iter(NULL, > > > + zswap_next_shrink, NULL); > > nit: this can fit in a single line right? Looks like it's exactly 80 ch= aracters. > > Isn't that over 90 chars? But yes, we can reduce line breaks using > memcg as temporary, like: Huh. Weird. I applied the patch locally, and it looked 80 chars to me ha. Anyway - just some nits. If checkpatch complains then yeah no need to fix t= his.