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b=e/remgRTygW4nP9e0YNyUCfjv21u2efHFTMBbCdOU3kuMSWeVBVSjw04J2ryrMGqV yRLQiS9fAb600VrrtkaAXQ0cva/E/quQDrPzZICbfAZeoIljnXqS6MlJ9qE6FyUfZs J8bsJIyx++H8AqGsHw031MCQ6Kzat7ECuidYguky25HO2LeqG6hmtjQ5XuamiHLhnG lIssWFxP+cCuAfRI2IhhpTpbrIHCR1wUc8geJ0YP77vY5XBn/7fxtl6xOuP1JjqkBy HngzDuSQ72hy/k+d1Z7P97t4+8Ux8op+PURRwF7h+1NIDDRsJCSycyfXzRGWX5jSBl uUsolt8SBz88g== Received: by mail-pg1-f175.google.com with SMTP id 41be03b00d2f7-53fbf2c42bfso1965073a12.3 for ; Fri, 10 Nov 2023 15:10:09 -0800 (PST) X-Gm-Message-State: AOJu0YzxAjh8DhTsCODR8xghTGrMyfBZjezPy+YgDMOuqMkmtkOl1hQ1 Zo8n3XswKp+CkWeEBuhPmxRuZGwUCz/Wf700FVqVyA== X-Google-Smtp-Source: AGHT+IHT0Ga3k2HwehobvQ094KpaDzUHoTF0BQnVAyg9rq61jKUTEPBaI8omUev0xwQiA7zEScehe6jVq87qUxqw8NI= X-Received: by 2002:a17:90b:4f8a:b0:27f:df1a:caab with SMTP id qe10-20020a17090b4f8a00b0027fdf1acaabmr552651pjb.21.1699657808503; Fri, 10 Nov 2023 15:10:08 -0800 (PST) MIME-Version: 1.0 References: <20231106231158.380730-1-nphamcs@gmail.com> In-Reply-To: <20231106231158.380730-1-nphamcs@gmail.com> From: Chris Li Date: Fri, 10 Nov 2023 15:09:56 -0800 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH v4] zswap: memcontrol: implement zswap writeback disabling To: Nhat Pham Cc: Andrew Morton , tj@kernel.org, lizefan.x@bytedance.com, Johannes Weiner , Domenico Cerasuolo , Yosry Ahmed , Seth Jennings , Dan Streetman , Vitaly Wool , mhocko@kernel.org, roman.gushchin@linux.dev, Shakeel Butt , muchun.song@linux.dev, Hugh Dickins , corbet@lwn.net, Konrad Rzeszutek Wilk , senozhatsky@chromium.org, rppt@kernel.org, linux-mm , kernel-team@meta.com, LKML , linux-doc@vger.kernel.org, david@ixit.cz Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Queue-Id: 3CF87160010 X-Rspam-User: X-Rspamd-Server: rspam05 X-Stat-Signature: s7h7txh7ugqe469ysgzyzs9xistz7xqu X-HE-Tag: 1699657811-993856 X-HE-Meta: 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 h12Hio7E fEwJN2aFuhmfQFqD6rZCx2zSgvGIK7Gf3bMFIxm4ooM/3EXV0P6vEAPiwt8nYZoLHQnjYOPSf2bq3+bsEX5IXVLvp1Eu67ZbsG48j6CYljVnop3T0f4lQjHlOm0J6EmLRcR4AzNnApUejjFtOfUUU8VuT02apPGn2gIMmLgMD6fW9PK0+VF21zB8TkFTtE6VBHrc5wh2EHhqR5YDKRsMaCYQTIA78XyTwg6+Bu4Cbgd7CraqEayms/aPIsKyrnByyaUs5RjeQ8G5GPWIcXU80uygblbSdmYTHa0maP53F0o0vJ9Q= 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: Hi Nhat, Acked-by: Chris Li On Mon, Nov 6, 2023 at 3:12=E2=80=AFPM Nhat Pham wrote: --- a/include/linux/memcontrol.h +++ b/include/linux/memcontrol.h @@ -219,6 +219,12 @@ struct mem_cgroup { #if defined(CONFIG_MEMCG_KMEM) && defined(CONFIG_ZSWAP) unsigned long zswap_max; + + /* + * Prevent pages from this memcg from being written back from zswap= to + * swap, and from being swapped out on zswap store failures. + */ + bool zswap_writeback; #endif I notice the bool is between two integers. mem_cgroup structure has a few bool sprinkle in different locations. Arrange them together might save a few padding bytes. We can also consider using bit fields. It is a very minor point, the condition also exists before your change. > #endif /* _LINUX_ZSWAP_H */ > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > index e43b5aba8efc..9cb3ea912cbe 100644 > --- a/mm/memcontrol.c > +++ b/mm/memcontrol.c > @@ -5545,6 +5545,11 @@ mem_cgroup_css_alloc(struct cgroup_subsys_state *p= arent_css) > WRITE_ONCE(memcg->soft_limit, PAGE_COUNTER_MAX); > #if defined(CONFIG_MEMCG_KMEM) && defined(CONFIG_ZSWAP) > memcg->zswap_max =3D PAGE_COUNTER_MAX; > + > + if (parent) > + WRITE_ONCE(memcg->zswap_writeback, READ_ONCE(parent->zswa= p_writeback)); > + else > + WRITE_ONCE(memcg->zswap_writeback, true); You can combine this two WRITE_ONCE to one bool writeback =3D !parent || READ_ONCE(parent->zswap_writeback); WRITE_ONCE(memcg->zswap_writeback, writeback); Chris