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[109.81.25.183]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-48de0967affsm10286573f8f.1.2026.10.14.04.46.24 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 14 Oct 2026 04:46:24 -0700 (PDT) Date: Wed, 14 Oct 2026 13:46:23 +0200 From: Michal Hocko To: Shakeel Butt Cc: Andrew Morton , Johannes Weiner , Roman Gushchin , Muchun Song , Tejun Heo , Meta kernel team , cgroups@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH for-7.5 5/5] memcg: simplify high limit handling after a charge Message-ID: References: <20261010210957.1350874-1-shakeel.butt@linux.dev> <20261010210957.1350874-6-shakeel.butt@linux.dev> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20261010210957.1350874-6-shakeel.butt@linux.dev> X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 7AA15A000E X-Rspam-User: X-Stat-Signature: 7w15ey6bcryqaahabmhax36ta56fqk89 X-HE-Tag: 1791978386-979380 X-HE-Meta: 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 0ptif5ey bUl1Nla/eWwd5gAiMRxkDCi6DyJYusOlwrrj8hXk405NnjlnGAuD8kIivUVJ/NFa83GzzEQrWPRsKgZVKc31ABJOt8Xb7tBsi9pUyztoBbFgA17AQuf1U2P0RBuZpAGYpTlxLMAqjeR/zAlqXEVeA6D3+/OAiWgF1MWYhYtt3aq7U/mN1Y2KApcylBv68LZPpluOB1j0IlhoOUYZbnhE0di3mpRiLMoiHRbduOBTd2ODBUifUnIZkW9S9S+FlUiEq6T/S1d/QA4/3yHeGSrTcMZHSrTkohCREfwk715EB+1BbitpdNBD3P83z27OOV+gNl4DnllP1KvQP9IC02Ho4wTv0u8s4lXYK4H2J/NHKUCQvnqk= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Sat 10-10-26 14:09:57, Shakeel Butt wrote: [...] > - /* Interrupts, kernel threads, and remote chargers stop here. */ > - if (use_worker) > + /* > + * Use a worker for interrupts, kernel threads, and tasks whose mm > + * does not match the charged hierarchy. > + */ > + if (use_high_work) { > + if (!iter) > + return; > + if (allow_spinning) > + schedule_work(&iter->high_work); > + else > + irq_work_queue(&iter->high_irq_work); > return; > + } > + > + if (iter) { Would it be much simpler to bail out on iter==NULL (i.e. nothing over high limit) right after the loop? > + /* > + * Count the full batch so reclaim work and delay penalties scale > + * with the pages charged by this task. > + */ > + current->memcg_nr_pages_over_high += nr_pages; > + set_notify_resume(current); > + } > > /* > - * Reclaim is set up above to be called from the userland > - * return path. But also attempt synchronous reclaim to avoid > - * excessive overrun while the task is still inside the > - * kernel. If this is successful, the return path will see it > - * when it rechecks the overage and simply bail out. > + * Earlier charges may have left high overage pending even if this charge > + * found no new overage. Handle it now if this charge can block, to limit > + * overrun while the task remains in the kernel. > */ > if (current->memcg_nr_pages_over_high > MEMCG_CHARGE_BATCH && > !(current->flags & PF_MEMALLOC) && > -- > 2.53.0-Meta -- Michal Hocko SUSE Labs