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McKenney" Cc: Andrew Morton , Catalin Marinas , puranjay@kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, bpf@vger.kernel.org, kernel-team@meta.com Subject: Re: [PATCH] mm/kmemleak: report RCU-tasks quiescent states during the scan Message-ID: References: <20260720-kmemleak_rcu_task-v1-1-5b460ade777d@debian.org> <20260720153917.2e428e489cd0873ac6d4e6da@linux-foundation.org> <5b83b0a0-708a-458a-bdbd-41c6d4610349@paulmck-laptop> <39c90e82-f785-4b47-9571-dd4b1339d685@paulmck-laptop> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-Debian-User: leitao X-Rspamd-Queue-Id: 09595160012 X-Stat-Signature: z6qbeosr1g7bxgb3wghreow3qme7u93e X-Rspam-User: X-Rspamd-Server: rspam04 X-HE-Tag: 1786356065-87060 X-HE-Meta: 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 7H92m5Nu +ikDK10Y/CtfBTGUV/+dGIoTyWbRkF4nMVc7GE29grGmPR1aRrmTZB4jdYBEph4VXWrUfyAUg3083rLV2p4afo3xkThHKLOUVgP181UF/EXKa4h5d3G8l1VeKyJpP3tnFO17DhDh3IF1rQVDDydNC+VzAYYsANKLPTLHF7EP24uSc8z3A2alCThuzlYWmxmgnuYtqFjbxT+7IbvIse6WWK47fqeHsYyj9115Dj8o7kWgeeZ3RlY5cpmb6KXI8t1R6CWStdUd2NBwc9H6xuggfR0oqHuXBJfVsAlW9dC2kvdm72w14Eshh0dyvhrAHBW4slssRT5R1V4d1xvM= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon, Jul 27, 2026 at 06:04:37AM -0700, Breno Leitao wrote: > I found 3 different cases on Meta fleet, where rcu task stalls show up: > > 1) kmemleak -> This patch solves it > 2) KVM / kcompactd > * Holdout: kcompactd0 (pid 1216), state:R, nvcsw frozen at > 716336/716336 across three reports 10 min apart (stuck ≥20 min in > one compaction pass) > * This is coming from: migrate_pages -> > kvm_mmu_notifier_invalidate_range_start -> > tdp_mmu_next_root -> tdp_mmu_zap_leafs > > 3) Nvidia driver > * stuck in nv_procfs_read_lock_params I've found an additional one: 4) While shrinking in reclaim: INFO: rcu_tasks detected stalls on tasks: 0000000088620d09: .. nvcsw: 6735/6735 holdout: 1 idle_cpu: -1/8 task:GlobalCPUThread state:R running task pid:2552016 tgid:2524552 Call Trace: shrink_lruvec mem_cgroup_iter shrink_node I've proposing promoting cond_resched() to cond_resched_tasks_rcu_qs(): https://lore.kernel.org/all/20260810-rcu_task_shrink_lruvec-v1-1-4d9f7d5251cb@debian.org/