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b=fdAh6JKa5mh0/MqvHlpkLuJPgooksUSw1I03/zFOSRcjE51am+cnML3xs6q4R8cix p09soHyoMBtcQnxuaU/gbgRVdAFEvKbD02BKhtO444gzczGPAcXm+q56r65ycct5v/ jf+GkPGBv0NRO39W4mRpSOmKLUnJnjhG4rSB2y7j0aPSHXEi468LylB61yoPDpD2zE t5D7YdShnUZP2dlGBKIahIJt4fIBdecR+o3WwuSaKPBnGqchGZTDgq5ngEFGMekDMC zFLytQWQ25FRnDLXZfH2TzSvMtuU4JAt3vuzNUrvzoCN8aZQvbnnH6WUMyDThx2q+8 3wT3d947mXv8Q== Date: Tue, 15 Apr 2025 09:30:35 -1000 From: Tejun Heo To: Michal =?iso-8859-1?Q?Koutn=FD?= Cc: JP Kobryn , shakeel.butt@linux.dev, yosryahmed@google.com, hannes@cmpxchg.org, akpm@linux-foundation.org, linux-mm@kvack.org, cgroups@vger.kernel.org, kernel-team@meta.com Subject: Re: [PATCH v4 5/5] cgroup: use subsystem-specific rstat locks to avoid contention Message-ID: References: <20250404011050.121777-1-inwardvessel@gmail.com> <20250404011050.121777-6-inwardvessel@gmail.com> <3ngzq64vgka2ukk2mscgclu6pcr6blwt3cwwmdptpdb7l7stgv@vhpyjbzbh63h> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <3ngzq64vgka2ukk2mscgclu6pcr6blwt3cwwmdptpdb7l7stgv@vhpyjbzbh63h> X-Rspam-User: X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: CC4CA180018 X-Stat-Signature: imdgqonqs5scfja3jfgyiffz5dii5rhw X-HE-Tag: 1744745437-420931 X-HE-Meta: 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 9WOFnSVe j5Hnga4mu8rKDRJLSYHIJVK6iGa34fnvaj93gRlcugDSCV3zFcV4gq9bOaj/1huAc7xhhQlStLxhnfPIdL6USIlH5F35SXF4q7+7gTCWaW4cUF7I7IYA6kp6YrQuqjdNxwGo2XnHGeBm1ZeTRVpBLPEV/w6JhSoPkuEOdH/GHA3TjyXcvXXKnRCarYkevekPntKhJf4RQxVxi734paakl3pXprMk0hpw6ZpIQz9ko3hFdg8EakSnL1GIelpRQ46P1HPed 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 Tue, Apr 15, 2025 at 07:15:48PM +0200, Michal Koutný wrote: > On Thu, Apr 03, 2025 at 06:10:50PM -0700, JP Kobryn wrote: > > --- a/kernel/cgroup/rstat.c > > +++ b/kernel/cgroup/rstat.c > ... > > static inline void __css_rstat_lock(struct cgroup_subsys_state *css, > > int cpu_in_loop) > > - __acquires(&cgroup_rstat_lock) > > + __acquires(lock) > > Maybe > __acquires(ss_rstat_lock(css->ss)) > > It shouldn't matter anyway but that may be more specific than a > generic 'lock' expression [1]. I don't know whether this is a controversial opinion but I personally would prefer to not have __acquires/__releases() notations at all. They add unverifiable clutter and don't really add anything valuable on top of lockdep. Thanks. -- tejun