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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: <39c90e82-f785-4b47-9571-dd4b1339d685@paulmck-laptop> X-Debian-User: leitao X-Stat-Signature: 1nsh8fatpxoj7ztxckydnb6jaqsdeimi X-Rspam-User: X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: B31191C000B X-HE-Tag: 1785157502-44851 X-HE-Meta: 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 r44EMuR9 RB/WOeysCuHTkvjmCHSUGfeK8gmuPgCHMRq6oOeXOWHYNdYNdbmOQT0pVFRLB30ItqE/p9Si6RbIUJ1M0ywF+14itutyuIri52Ij9C8MwxKtNmVfqrrJfMh08aJRi4hT1acMtnFRcHp+DJ6qaFY+vffNJHzNRFAH5lhGGDfeGePR98rmEWjfpMLnpLCDaBPyR3bDL19vz7+DVPlL+LfYEBbPJVuTBnXzJnJjIQ0pJ45rZ+2W1usLQrqU0HyltoXdhwL0DAXSmhpEdgpwebT3bMMREuw== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: > > The document was not a waste of time. it helped people like me to > > understand what the issue is, and what are the decisions we have ahead > > of us. > > > > Back to what is the best decision/design, I honestly don't have an > > opinion, but I am happy to get more data about Meta production servers > > to help with the decision. > > Looking forward to seeing what you come up with! 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 Given we can't do much about 3) and 1) is now closed, I will spend some time geting more data and possible a fix for 2.