From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from stravinsky.debian.org (stravinsky.debian.org [82.195.75.108]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id B42852D3ECF; Mon, 27 Jul 2026 13:05:04 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=82.195.75.108 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785157506; cv=none; b=G15BOKQhpTvawtlb5nnrhNz97nyBYYQirVKkipqCF02+Daymmxp/Ia77vG7njghPj5lkJsbIWUi6Nollo1TB+oFzQPoSCAVT/+uujbGnCNS3L86jgtIndFLHCWS1pmUfuWbdxoJSIXOrJNFCIGWXSYRoWxp28XbljjvQFprg1Ng= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785157506; c=relaxed/simple; bh=TbXEodD4bBw0Du7sllvZPgf10XkwARfXOFSrxeJ3mEc=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=PBraLQJAwlpHQi+6cdIKuMYk8nRLe4Xh7Usg+VPweQssKbUrSKNnCmbMcXU7F69gcx4vZ+aJA8RWg//88xXgehcizI26G7Owb/smO6kxt88Kg1UlT0rpzsJbf/QDoOJf3WEqn3i2pTHRFUGkq0n2nipl9t5V+JJh/JVZcktOHxk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=debian.org; spf=pass smtp.mailfrom=debian.org; dkim=pass (2048-bit key) header.d=debian.org header.i=@debian.org header.b=Ht5Jap5i; arc=none smtp.client-ip=82.195.75.108 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=debian.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=debian.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=debian.org header.i=@debian.org header.b="Ht5Jap5i" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=debian.org; s=smtpauto.stravinsky; h=X-Debian-User:In-Reply-To:Content-Transfer-Encoding: Content-Type:MIME-Version:References:Message-ID:Subject:Cc:To:From:Date: Reply-To:Content-ID:Content-Description; bh=s9wWiDjCW477tgZIUjVpQbdu88BE7PfzDyOZG1n0onM=; b=Ht5Jap5i77PnqRGHRJ802tXx0a O0b3rd4TWLwB3x2XgwTlCrpDZzrM3Gf42i30XVOZSnCwrLQZ4gw0i1L2uUovANqFW+cBIAAaXPiRb AgpskSy8py7EGSxkV6eY5FdnBBugHkPHuBrTJr1YM2AwJ6BAd9edCnoGgFgL6rItqvEbnG6ITkQhQ IzIZiaCsuq645/RTDjOLOahDvGWOwkAr69MGaU8C3l0BBRsvikl5Sgj0ZgwOlnN6iDqz1t0UgOgC/ nuVCcppC1qxuGmCx4LnFJ7Hv8zNrUkW+7YKO3YgPhhQ8WzRUPhhtN26m65ldg+BGawqO3anAQQmLo 8uTm1X/Q==; 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 1woL0r-006utr-0Y; Mon, 27 Jul 2026 13:04:57 +0000 Date: Mon, 27 Jul 2026 06:04:37 -0700 From: Breno Leitao To: "Paul E. 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> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: 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 > > 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.