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Howlett" , linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-kselftest@vger.kernel.org, kernel-team@meta.com Subject: Re: [PATCH v3 0/2] mm/kmemleak: dedupe verbose scan output Message-ID: References: <20260506-kmemleak_dedup-v3-0-2d36aafc34da@debian.org> <20260508151729.682551a2b2739e8b5d15ade2@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260508151729.682551a2b2739e8b5d15ade2@linux-foundation.org> X-Debian-User: leitao X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: AF7E340006 X-Stat-Signature: tdi5hkhrob458qy7qa318wwohm16wn1k X-Rspam-User: X-HE-Tag: 1778514133-201820 X-HE-Meta: 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 ehIY3j1P 6nKlGXtotUnwCsgdTS4MwV4X79srU1IkEHEZP7yeAw0dgCaqtm9xdiMN8+eMOQNTbm5jTvyF3BQ14ouVvfB/XWy+J8+UgwvSs82ArOyhRN58V9U/rEPMd3OZz1TtJrcWDPWqhl2gwfOi7zNRI/LJG7EEt8wsJOt61DxLk9/fLb2sIJgIzZ7LHQuG3/NMh70IN2J0nWET7lA1vyYFmJradfS6MPH0uxFgvXi75c47l8Cc2vLOXtsU9mbdBn7WFXDs5fD3W3ZCp4ls/0pHWQ9pdK2ZmgsHKvMTPt9D8DivXM/uwRsc= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Fri, May 08, 2026 at 03:17:29PM -0700, Andrew Morton wrote: > On Wed, 06 May 2026 05:58:23 -0700 Breno Leitao wrote: > > > In this version, I am not touching the kernel code, but, just fixing > > the selftest, as sashiko reported some issues, and I am addressing them > > in here. > > > > https://sashiko.dev/#/patchset/20260424-kmemleak_dedup-v2-0-8bea649b2a92%40debian.org > > > > NOTE: Additional testing has revealed that lockdep detects a potential lock > > inversion issue on kmemleak and legacy console. > > > > The problem occurs because the function holds &object->lock (a raw spinlock) > > while invoking printk to report the leak. This printk requires the legacy > > console_owner lock, which remains in active use despite the ongoing transition > > to the nbcon framework. > > > > Concurrently, console drivers such as hvc (hypervisor virtual console) acquire > > the console_owner lock and may subsequently free memory. This kfree() operation > > calls into kmemleak's __delete_object(), which in turn acquires object->lock. > > > > Although these code paths hold locks from different object instances, lockdep > > operates on lock classes rather than individual instances. Since all > > kmemleak_object->lock instances belong to the same lock class, lockdep > > identifies this as a circular dependency, even though the actual deadlock > > scenario cannot occur in practice (?!). > > > > This problem was not introduced by this patchset/selftest, but, it is exposing > > it. I plan to solve it once this patchset is done. > > None of the above is usable for a [0/N] - it all pertains to the > ongoing development process and should formally be below the ^---$ > separator. Because it isn't relevant to the permanent kernel record. > > The v2 series had a nice cover letter, so I stole that. Please check > that the below remains the truth, the whole truth, etc. Ack, That remains correct. I just updated the cover letter to reflect the changes, but in the future I will keep the overall goal of the patchset.