From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 274B2C04EB8 for ; Tue, 4 Dec 2018 21:50:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E68EF2082B for ; Tue, 4 Dec 2018 21:50:39 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E68EF2082B Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726591AbeLDVui (ORCPT ); Tue, 4 Dec 2018 16:50:38 -0500 Received: from mx1.redhat.com ([209.132.183.28]:33568 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725875AbeLDVui (ORCPT ); Tue, 4 Dec 2018 16:50:38 -0500 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 7527CC0740F2; Tue, 4 Dec 2018 21:50:37 +0000 (UTC) Received: from llong.remote.csb (dhcp-17-55.bos.redhat.com [10.18.17.55]) by smtp.corp.redhat.com (Postfix) with ESMTP id D18B55D786; Tue, 4 Dec 2018 21:50:35 +0000 (UTC) Subject: Re: [PATCH v2 21/24] locking/lockdep: Verify whether lock objects are small enough to be used as class keys To: Bart Van Assche , mingo@redhat.com Cc: peterz@infradead.org, tj@kernel.org, johannes.berg@intel.com, linux-kernel@vger.kernel.org, Johannes Berg References: <20181204002833.55452-1-bvanassche@acm.org> <20181204002833.55452-22-bvanassche@acm.org> <8ae6bb3f-ab75-e6f2-adfa-8003366b7410@redhat.com> <1543959553.185366.213.camel@acm.org> From: Waiman Long Openpgp: preference=signencrypt Autocrypt: addr=longman@redhat.com; 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Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: <1543959553.185366.213.camel@acm.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Content-Language: en-US X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.31]); Tue, 04 Dec 2018 21:50:37 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/04/2018 04:39 PM, Bart Van Assche wrote: > On Tue, 2018-12-04 at 16:08 -0500, Waiman Long wrote: >> On 12/03/2018 07:28 PM, Bart Van Assche wrote: >>> Cc: Peter Zijlstra >>> Cc: Waiman Long >>> Cc: Johannes Berg >>> Signed-off-by: Bart Van Assche >>> --- >>> kernel/locking/lockdep.c | 9 +++++++++ >>> 1 file changed, 9 insertions(+) >>> >>> diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c >>> index c936fce5b9d7..b4772e5fc176 100644 >>> --- a/kernel/locking/lockdep.c >>> +++ b/kernel/locking/lockdep.c >>> @@ -727,6 +727,15 @@ static bool assign_lock_key(struct lockdep_map *lock) >>> { >>> unsigned long can_addr, addr = (unsigned long)lock; >>> >>> + /* >>> + * lockdep_free_key_range() assumes that struct lock_class_key >>> + * objects do not overlap. Since we use the address of lock >>> + * objects as class key for static objects, check whether the >>> + * size of lock_class_key objects does not exceed the size of >>> + * the smallest lock object. >>> + */ >>> + BUILD_BUG_ON(sizeof(struct lock_class_key) > sizeof(raw_spinlock_t)); >>> + >>> if (__is_kernel_percpu_address(addr, &can_addr)) >>> lock->key = (void *)can_addr; >>> else if (__is_module_percpu_address(addr, &can_addr)) >> I don't understand what this check is for. lock_class_key and spinlock >> are different objects. Their relative size shouldn't matter. > Hi Waiman, > > Peter asked me to add this check. > > Bart. I haven't finished reviewing all your patches yet. Maybe one of the subsequent patches requires this. If that is the case, you should move this patch after that. -Longman