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a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1774354804; bh=nBpcshDUXGsdJq19WufZSbR45lWJYXUT8cWL/8Uyqxg=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=E176/AhErzCouvY3ETmgNShe8DY3jmhd2QAAePt1i+d8smXGBpjT73b+WJ3HX8mTx W+7sIromtOyZ6uD6pJX+avK8yrfPe/G+8jjRTQ6pkYoVho9fXlNnmKUykIbnTLkO1O O+UeQGhB49v0Ibm+X+oogwRU5Dh9ehpZui5UjS+jP/8pe3zjbvP2K+l1iG+h38j1E4 b1ExbsQO2EyJ39LjR9jyzBvQjifLZYFQRqZs3rRyIplBFd7Z0sfVFUGw5o3GjOGCmR C9Cu1ccXhRPQ95nqNOOgvXks0UkOEqIdHWk6UdR1CxV/pzOEsG2A0X6nsLmjQwc0hQ D1aY8EKqE6OoQ== Date: Tue, 24 Mar 2026 12:20:01 +0000 From: "Lorenzo Stoakes (Oracle)" To: Qi Zheng Cc: hannes@cmpxchg.org, hughd@google.com, mhocko@suse.com, roman.gushchin@linux.dev, shakeel.butt@linux.dev, muchun.song@linux.dev, david@kernel.org, ziy@nvidia.com, harry.yoo@oracle.com, yosry.ahmed@linux.dev, imran.f.khan@oracle.com, kamalesh.babulal@oracle.com, axelrasmussen@google.com, yuanchu@google.com, weixugc@google.com, chenridong@huaweicloud.com, mkoutny@suse.com, akpm@linux-foundation.org, hamzamahfooz@linux.microsoft.com, apais@linux.microsoft.com, lance.yang@linux.dev, bhe@redhat.com, usamaarif642@gmail.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Qi Zheng Subject: Re: [PATCH 1/3] mm: memcontrol: correct the type of stats_updates to unsigned long Message-ID: <095a503f-6967-45f1-99c0-03d4fc3baf0b@lucifer.local> References: <74022705dc8d5209ff7e603a178044fe4cfbae09.1774342371.git.zhengqi.arch@bytedance.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <74022705dc8d5209ff7e603a178044fe4cfbae09.1774342371.git.zhengqi.arch@bytedance.com> X-Stat-Signature: 9otgs5oq8z3srb5cbxnwf5auaxoie4uh X-Rspamd-Queue-Id: B649D40010 X-Rspam-User: X-Rspamd-Server: rspam03 X-HE-Tag: 1774354805-140882 X-HE-Meta: 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 AsyjWQJX UKo6JqlQK5YZ//hBmGweAIxfDkX35gw5BXfQ5IlFiI53DIvRTG3Rc20kJ4RKRM7yWz8D86nPD9xSglAeKdnixgU074fnKpm+so970X5SbNGdxLTRKqIclBa4qO5bmaGEH9orJmGIB/cZ/6LY4fymk0JZpnU8cWkQsPc/CuG09J5PKPas9c82A0ekAkRWH1+BXnXY/Nj5sUbKVqE4nN5zm4vZEAXoAVnlmdccvsLvqLDaF0XU17rwlCSNn5P4YyRKIQEyi1b7LlfmsxXpxQsFU1KUB8M4RVZfW247GkP+QvpJssNhTk4IJtm2IW03eN8CbT1D8 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: (-cc old mail) On Tue, Mar 24, 2026 at 07:31:27PM +0800, Qi Zheng wrote: > From: Qi Zheng > > Now, the memcg_rstat_updated() is for vmstats_percpu->state and Now? Did this change? If so, please put commit here in commit xxx ("blah") format, I don't want to have to try and look it up :P > lruvec_stats_percpu->state, which are both of type long, so let's change > the type of stats_updates to unsigned long as well. Is this a bug whereby before this could be overflowed? Or are you deciding to make these long now? Because it seems that are proactively making this change _yourself_. This comment message needs a lot more explanation. > > Signed-off-by: Qi Zheng > --- > mm/memcontrol.c | 18 +++++++++--------- > 1 file changed, 9 insertions(+), 9 deletions(-) > > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > index a47fb68dd65f1..7fb9cbc10dfbb 100644 > --- a/mm/memcontrol.c > +++ b/mm/memcontrol.c > @@ -608,7 +608,7 @@ static inline int memcg_events_index(enum vm_event_item idx) > > struct memcg_vmstats_percpu { > /* Stats updates since the last flush */ > - unsigned int stats_updates; > + unsigned long stats_updates; > > /* Cached pointers for fast iteration in memcg_rstat_updated() */ > struct memcg_vmstats_percpu __percpu *parent_pcpu; > @@ -639,7 +639,7 @@ struct memcg_vmstats { > unsigned long events_pending[NR_MEMCG_EVENTS]; > > /* Stats updates since the last flush */ > - atomic_t stats_updates; > + atomic_long_t stats_updates; > }; > > /* > @@ -665,16 +665,16 @@ static u64 flush_last_time; > > static bool memcg_vmstats_needs_flush(struct memcg_vmstats *vmstats) > { > - return atomic_read(&vmstats->stats_updates) > > + return atomic_long_read(&vmstats->stats_updates) > > MEMCG_CHARGE_BATCH * num_online_cpus(); > } > > -static inline void memcg_rstat_updated(struct mem_cgroup *memcg, int val, > +static inline void memcg_rstat_updated(struct mem_cgroup *memcg, long val, > int cpu) > { > struct memcg_vmstats_percpu __percpu *statc_pcpu; > struct memcg_vmstats_percpu *statc; > - unsigned int stats_updates; > + unsigned long stats_updates; > > if (!val) > return; > @@ -697,7 +697,7 @@ static inline void memcg_rstat_updated(struct mem_cgroup *memcg, int val, > continue; > > stats_updates = this_cpu_xchg(statc_pcpu->stats_updates, 0); > - atomic_add(stats_updates, &statc->vmstats->stats_updates); > + atomic_long_add(stats_updates, &statc->vmstats->stats_updates); > } > } > > @@ -705,7 +705,7 @@ static void __mem_cgroup_flush_stats(struct mem_cgroup *memcg, bool force) > { > bool needs_flush = memcg_vmstats_needs_flush(memcg->vmstats); > > - trace_memcg_flush_stats(memcg, atomic_read(&memcg->vmstats->stats_updates), > + trace_memcg_flush_stats(memcg, atomic_long_read(&memcg->vmstats->stats_updates), > force, needs_flush); > > if (!force && !needs_flush) > @@ -4406,8 +4406,8 @@ static void mem_cgroup_css_rstat_flush(struct cgroup_subsys_state *css, int cpu) > } > WRITE_ONCE(statc->stats_updates, 0); > /* We are in a per-cpu loop here, only do the atomic write once */ > - if (atomic_read(&memcg->vmstats->stats_updates)) > - atomic_set(&memcg->vmstats->stats_updates, 0); > + if (atomic_long_read(&memcg->vmstats->stats_updates)) > + atomic_long_set(&memcg->vmstats->stats_updates, 0); > } > > static void mem_cgroup_fork(struct task_struct *task) > -- > 2.20.1 >