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Fri, 10 Jul 2026 04:50:10 -0700 (PDT) Date: Fri, 10 Jul 2026 07:50:09 -0400 From: Johannes Weiner To: Qi Zheng Cc: Harry Yoo , Usama Arif , akpm@linux-foundation.org, david@kernel.org, kasong@tencent.com, shakeel.butt@linux.dev, baohua@kernel.org, axelrasmussen@google.com, yuanchu@google.com, weixugc@google.com, muchun.song@linux.dev, peiyang_he@smail.nju.edu.cn, mhocko@kernel.org, roman.gushchin@linux.dev, ljs@kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Qi Zheng , stable@vger.kernel.org Subject: Re: [PATCH v4] mm: mglru: fix stale batch updates after memcg reparenting Message-ID: References: <20260701145736.3785016-1-usama.arif@linux.dev> <2fb5ce53-666b-4b0a-a4ad-2b3a28c54768@kernel.org> <843f6d0d-e893-43ef-9cb3-1df21fb64b8d@linux.dev> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <843f6d0d-e893-43ef-9cb3-1df21fb64b8d@linux.dev> On Fri, Jul 10, 2026 at 02:19:15PM +0800, Qi Zheng wrote: > On 7/10/26 9:51 AM, Johannes Weiner wrote: > > On Thu, Jul 02, 2026 at 09:38:41AM +0800, Qi Zheng wrote: > >> On 7/1/26 11:59 PM, Johannes Weiner wrote: > >>> lruvec_live_lock_irq()? > >> > >> But lruvec_lock_irq() grabs the rcu lock too. :( > > > > Yes, but it's self-explanatory if you put it with those definitions: > > > > static inline void lruvec_lock_irq(struct lruvec *lruvec) > > { > > rcu_read_lock(); > > spin_lock_irq(&lruvec->lru_lock); > > } > > > > static struct lruvec *lruvec_live_lock_irq(struct lruvec *lruvec) > > { > > struct mem_cgroup *memcg = lruvec_memcg(lruvec); > > > > rcu_read_lock(); > > while (unlikely(memcg && css_is_dying(&memcg->css))) { > > memcg = parent_mem_cgroup(memcg); > > lruvec = mem_cgroup_lruvec(memcg, lruvec_pgdat(lruvec)); > > } > > spin_lock_irq(&lruvec->lru_lock); > > } > > All right, should the implementation for !CONFIG_MEMCG be placed here > too? Yes. You can just #ifdef, #else the function body itself. static struct lruvec *lruvec_live_lock_irq() { #ifdef CONFIG_MEMCG ... #else lruvec_lock_irq(lruvec); return lruvec; #endif } > Will send the v5. Thanks.