From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (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 83BE63290BD for ; Thu, 16 Apr 2026 20:33:50 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.133.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776371632; cv=none; b=flj3VXMLTPW8zUVMy3iz4pq1f8ClxPImRJHfGOKd4rjodO4tBKfCwn/I2cOWhEAnlDR29yWfyhSzMKl2Jk7xt7Bvmo4mTe6Ptaxepq/TSNxfzXq9JN6qIbt+UXoaCQc1K2yJSO5nvEjLAYDCp1mvurEpMwbs5FQJMAXUQ/iJ14M= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776371632; c=relaxed/simple; bh=MzagrWVJOlIfBJ/nBLwbhEbooYHIuJCnb8Fpgiy6aQc=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=MXK/DOz9t3a6uEWpJaPExCekO+kd7Qne2xMXwlOI5SibUEoXIiyLxijmBs2EpUaUqjBqb8WojGIZ1uyXxdid7Cw++MS9dTKynYvX/LjTR2ct7vo5MzHoWE1jae9SNbk363ICtLHfkSWcc5GKOnDD2nioOMfw418oLqsax7WchCE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=E0SZmZzK; arc=none smtp.client-ip=170.10.133.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="E0SZmZzK" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1776371629; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=y75g7aYWacC65GEsmMEdp7oAC9v/KDF8tqJLxs9wOtA=; b=E0SZmZzKXbv91hl74PlKOwuaFahsyKaPHIivjAGTAEmj5ImbcyZR8a80LMORMGKmVr5L6J c+rfXODxCcBW2IkzMJ6Y1FUBFhts4Nu4oI6gTv2A++qa/EMEmnuiq7962ajfjypA+a0t7z ID9JiK+oIHytfFENZKH/bNQ3F+uDGrk= Received: from mx-prod-mc-08.mail-002.prod.us-west-2.aws.redhat.com (ec2-35-165-154-97.us-west-2.compute.amazonaws.com [35.165.154.97]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-628-1qJctB2oMMK58ANMPCZc3A-1; Thu, 16 Apr 2026 16:33:46 -0400 X-MC-Unique: 1qJctB2oMMK58ANMPCZc3A-1 X-Mimecast-MFC-AGG-ID: 1qJctB2oMMK58ANMPCZc3A_1776371625 Received: from mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.93]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 24DDB1800367; Thu, 16 Apr 2026 20:33:45 +0000 (UTC) Received: from x2.localnet (unknown [10.22.65.66]) by mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 21572180047F; Thu, 16 Apr 2026 20:33:43 +0000 (UTC) From: Steve Grubb To: Paul Moore Cc: Ricardo Robaina , audit@vger.kernel.org, linux-kernel@vger.kernel.org, eparis@redhat.com Subject: Re: [PATCH] audit: add backlog high water mark metric Date: Thu, 16 Apr 2026 16:33:42 -0400 Message-ID: <2620823.XAFRqVoOGU@x2> Organization: Red Hat In-Reply-To: References: <20260323150700.614139-1-rrobaina@redhat.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.93 On Wednesday, April 15, 2026 11:21:52=E2=80=AFAM Eastern Daylight Time Paul= Moore=20 wrote: > On Wed, Apr 15, 2026 at 11:19=E2=80=AFAM Paul Moore = wrote: > > On Tue, Apr 14, 2026 at 11:45=E2=80=AFPM Steve Grubb wrote: > > > On Friday, April 10, 2026 5:34:08=E2=80=AFPM Eastern Daylight Time Pa= ul Moore=20 wrote: > > > > On Mon, Mar 23, 2026 at 11:07=E2=80=AFAM Ricardo Robaina > > > > > > >=20 > > > wrote: > > ... > >=20 > > > ... compliance-driven systems that must use a finite backlog limit for > > > memory safety but cannot tolerate dropped events ...>=20 > > You must pick one of those two requirements, or at the very least > > prioritize them; it is simply impossible to both limit the backlog > > queue and require zero dropped events. >=20 > To be perfectly honest, it's also impossible to require zero dropped > events. Even in the most extreme configurations where the admin > decides to panic the system, that only happens once the system reaches > the point where it is dropping events. We try *really* hard to not > drop events, but it is always going to be a possibility. You're helping make the point. Those administrators have decided reliable= =20 auditing is more important than system availability. backlog_max_depth give= s=20 them the one thing they currently lack: advance warning. If the high-water= =20 mark is consistently approaching the backlog limit, they have actionable=20 information to raise the limit, reduce audit rule coverage, or address the= =20 underlying load - before the system goes down. These are exactly the users= =20 who would benefit the most from this metric. =2DSteve