From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (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 1C6183081D7 for ; Mon, 27 Oct 2025 14:56:05 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.129.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761576968; cv=none; b=C2/Rd+VjM25kYrKQ+nr6eQla9GRY2b48dUeMvxAx8GePSmElstXxEdN4WBUzRGfcVoUD79k+O/STgvJqGlcqRE/QnzHqc8M30by+INTcZqYPQ86kVrhaLnDJdTLdxI03JZOYFSl1Cai7auqfSxzcPt64JubYQOeV3kp/6vMkLEw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761576968; c=relaxed/simple; bh=MdHdwbyRwOneokDrrak8W58rH/i7XxR4qPE6h2RGc/0=; h=From:In-Reply-To:References:To:Cc:Subject:MIME-Version: Content-Type:Date:Message-ID; b=IXGBFDCwSnfKRHLThBBeUCGEp6eBAyyRW1l41b/fBEIop/0xozFiR3+kSO4KkvjhXrPbMXFJ3q6pn3RnSGUNFIQnmTy3V6xsu8PifGuLle5Ewn2Am439fSVzp0W6jxQoiCz6ihz4nY7DOXKld7z6GHjyhyuHa0Of4fzTOlMAkB0= 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=RcM+SSkA; arc=none smtp.client-ip=170.10.129.124 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="RcM+SSkA" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1761576965; 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=oLyWzWnQzJKD0XolAql4Q3+iH78Y+upjEhl1CSo9Dzw=; b=RcM+SSkAPHoCYnYsDkFzwi8TXJKTXwyjj87gSgaA7gh8728i9GiRM2YG8NcfuNwnu6XsTY 3nUkW0BXjfwEbxOuWdjrEaPUDp7Wk0s3Fi1CRdPAWBNeva5/YD/NxSrVlV2qyGKh22VmRC y4rHHFYHVMIuU1VGzbr5JZ1D0j0pxBs= Received: from mx-prod-mc-01.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-563-kXZrtj4dNwuzfVfBFUHFcQ-1; Mon, 27 Oct 2025 10:56:00 -0400 X-MC-Unique: kXZrtj4dNwuzfVfBFUHFcQ-1 X-Mimecast-MFC-AGG-ID: kXZrtj4dNwuzfVfBFUHFcQ_1761576959 Received: from mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.12]) (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-01.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 87A55196F747; Mon, 27 Oct 2025 14:55:59 +0000 (UTC) Received: from warthog.procyon.org.uk (unknown [10.42.28.6]) by mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id B9CFA19560B2; Mon, 27 Oct 2025 14:55:57 +0000 (UTC) Organization: Red Hat UK Ltd. Registered Address: Red Hat UK Ltd, Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SI4 1TE, United Kingdom. Registered in England and Wales under Company Registration No. 3798903 From: David Howells In-Reply-To: <20251026143501.GA22472@redhat.com> References: <20251026143501.GA22472@redhat.com> <20251026143140.GA22463@redhat.com> To: Oleg Nesterov Cc: dhowells@redhat.com, Alexey Gladkov , Andrew Morton , Mateusz Guzik , "Paul E. McKenney" , linux-kernel@vger.kernel.org Subject: Re: [RFC 2/1] kill task_ucounts()->rcu_read_lock(), add __task_ucounts() 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="us-ascii" Content-ID: <2258931.1761576956.1@warthog.procyon.org.uk> Content-Transfer-Encoding: quoted-printable Date: Mon, 27 Oct 2025 14:55:56 +0000 Message-ID: <2258932.1761576956@warthog.procyon.org.uk> X-Scanned-By: MIMEDefang 3.0 on 10.30.177.12 Oleg Nesterov wrote: > So I think task_ucounts() can just do > = > /* The caller must ensure that ->real_cred is stable or take rcu_read_l= ock() */ > #define task_ucounts(task) \ > rcu_dereference_check((task)->real_cred, 1)->ucounts Can you use rcu_access_pointer() within exit.c? E.g.: struct cred *pcreds =3D rcu_access_pointer(task->real_cred); dec_rlimit_ucounts(pcreds->ucounts, UCOUNT_RLIMIT_NPROC, 1); David