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AJvYcCVSQlxlhRt5HM7+AsewBB1C1mz4gfl7PtBEZlgZGWUGJLQk3PMhmO7Y5XtqHDK09OgMkaCwu6Qtvw==@kvack.org X-Gm-Message-State: AOJu0YxVyzgAuO8RYQeAGrZq2Rb3g0usrZKrt1Fj1iyE3nZ66riPQDxK OJGkspl3HPP6FZRIk1+2l6hIsHQqCn3XTmqr09lQ1CDm4uPQrX4rif+XeoG3R/ZsUMUoJvKtkho CG/84gOumOwnH77p3FbPGfC0lxHlc1P/lt256 X-Google-Smtp-Source: AGHT+IFUTfSFqD0LJ8fBf/qBjK9gkH3Z9YIIz4iHZrS73DoGiaBlQz65rZWWLT2VwceQlhDcqTGP7QpWRdHLEYK/iBw= X-Received: by 2002:a17:907:6d29:b0:a8a:58c5:78f1 with SMTP id a640c23a62f3a-a9ad2711791mr278966966b.11.1729802009584; Thu, 24 Oct 2024 13:33:29 -0700 (PDT) MIME-Version: 1.0 References: <20241024065712.1274481-1-shakeel.butt@linux.dev> <20241024065712.1274481-4-shakeel.butt@linux.dev> <7w4xusjyyobyvacm6ogc3q2l26r2vema5rxlb5oqlhs4hpqiu3@dfbde5arh3rg> In-Reply-To: From: Yosry Ahmed Date: Thu, 24 Oct 2024 13:32:53 -0700 Message-ID: Subject: Re: [RFC PATCH 3/3] memcg-v1: remove memcg move locking code To: Michal Hocko Cc: Shakeel Butt , Roman Gushchin , Andrew Morton , Johannes Weiner , Muchun Song , Hugh Dickins , linux-mm@kvack.org, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-doc@vger.kernel.org, Meta kernel team Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspam-User: X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 56E494000E X-Stat-Signature: fr7kthi9oti11r6ts3j1rtqs45aq4w8k X-HE-Tag: 1729801987-92517 X-HE-Meta: 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 MoJ8rioY IkPzurmjBifJzTNQxPnaFuEcw5zmcb5Ytx3e53f0eXMMWjFSaBcculXlwqrxThnTwjvafIAK2z5S5vPUgqpqThVVgt6mqWg+GJH/4iUw1FeK8cP5KQ4YLSx9FKNYIvDbTzP6h84XA/9yyI6i1mJRd2F9mY9/npHDZp6CXYi/Xq7ZplkpDSljlaUCrN2jRK4YytNSdAh3GSUvK/xIyTfvnX9w7mDVYn8x+sMU7MaJxWC+I6pDKI81tKHtkPK3ljTaDUZgO 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: On Thu, Oct 24, 2024 at 12:45=E2=80=AFPM Michal Hocko wro= te: > > On Thu 24-10-24 10:26:15, Shakeel Butt wrote: > > On Thu, Oct 24, 2024 at 04:50:37PM GMT, Roman Gushchin wrote: > > > On Wed, Oct 23, 2024 at 11:57:12PM -0700, Shakeel Butt wrote: > > > > The memcg v1's charge move feature has been deprecated. There is no= need > > > > to have any locking or protection against the moving charge. Let's > > > > proceed to remove all the locking code related to charge moving. > > > > > > > > Signed-off-by: Shakeel Butt > > > > > > Reviewed-by: Roman Gushchin > > > > Thanks Roman for the review. Based on Michal's question, I am planning > > to keep the RCU locking in the next version of this patch and folowup > > with clear understanding where we really need RCU and where we don't. > > I think it would be safer and easier to review if we drop each RCU > separately or in smaller batches. FWIW if we go with this route, I agree with Roman's idea about replacing folio_memcg_lock()/unlock() with an explicit rcu_read_lock()/rcu_read_unlock(), and then having separate patches/series that remove the RCU annotations. If done in a separate series, we should comment the explicit RCU calls appropriately to reflect the fact that they should mostly be removed (or at least re-evaluated).