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Received: from authenticated-user by stravinsky.debian.org with esmtpsa (TLS1.3:ECDHE_X25519__RSA_PSS_RSAE_SHA256__AES_256_GCM:256) (Exim 4.96) (envelope-from ) id 1wi6xT-004MUP-2X; Fri, 10 Jul 2026 08:51:44 +0000 Date: Fri, 10 Jul 2026 01:51:40 -0700 From: Breno Leitao To: Catalin Marinas Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Andrew Morton Subject: Re: [PATCH] mm: kmemleak: confirm suspected leaks with a second scan Message-ID: References: <20260709173347.689607-1-catalin.marinas@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260709173347.689607-1-catalin.marinas@arm.com> X-Debian-User: leitao X-Rspam-User: X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: A47BEC0002 X-Stat-Signature: f194ifknzctxfr8nwsuuuk1gwghkk8ss X-HE-Tag: 1783673506-786998 X-HE-Meta: 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 GxdKnDZy mj2RmWeIXwnFH4NGF7xVLGV/P/H/KlIJSMpXYILSquBv9ClsnJAU/qAKlSXOkOq8NBhy4YfOReEhRGkiMi2OirNlfdkHO4G+4KL74BNCbJVqk/fdGzqUyuhuCmtsrA625CLvn2UjrMatc1kawXQf7biiBp10L/NWsSqcMvbizRe99TzIyaAG7qVlGxO5BsH12Sk0bj/GXP4vU3FQZVn/pA1SKyBb6DLTbf4CZLhkL0Lp5e7iO8UioStp4NoGlRZ+CdYNEylBCk0ZmEearx8q9QPrfB+ki/x55RZ6skzKdqwAv5n0ABOksxI85wJbdPk65qvTAAdzNbg3tlXIHktTGeD7GhaXrU4WcvF2npIzkOobZ5TdF8Ovvh76QFOzU7NLepRhYBcz6lcKop4o= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Thu, Jul 09, 2026 at 06:24:47PM +0100, Catalin Marinas wrote: > The kmemleak marking phase is not atomic. While the object graph is > traversed, the kernel can modify pointers, free objects or allocate new > ones. If a reference to an object is moved from one location to another, > kmemleak scanning may miss it. We have explicit annotations like > kmemleak_transient_leak() but identifying and maintaining them is not > trivial. > > Given that such transient leaks are short-lived, rather than just > reporting such objects as leaks, do another scan to confirm the > suspected objects. If no new leaks are found during the first scan, skip > the confirmation one. > > Signed-off-by: Catalin Marinas > Assisted-by: Claude:claude-opus-4-8 > Cc: Breno Leitao > Cc: Andrew Morton Tested-by: Breno Leitao Reviewed-by: Breno Leitao PS: This is now conflicting with commit 946935b07cc94 ("mm/kmemleak: skip the remaining scan phases when interrupted"), which has just showed up in linux-next. So, a respin might be required. > BTW, I'll be away from Saturday for three weeks. I may reply > occasionally but won't be able to test anything. Let me know if you want me to respin it based on linux-next. BTW: Really thanks for doing it. I will backport it to Meta's kernel to pressure-test it and keep an eye on false positives. --breno