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=-11.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_2 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 4D82FC433E7 for ; Wed, 14 Oct 2020 15:38:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A24AE2222C for ; Wed, 14 Oct 2020 15:38:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730326AbgJNPi1 (ORCPT ); Wed, 14 Oct 2020 11:38:27 -0400 Received: from mail.kernel.org ([198.145.29.99]:45360 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726954AbgJNPi0 (ORCPT ); Wed, 14 Oct 2020 11:38:26 -0400 Received: from gandalf.local.home (cpe-66-24-58-225.stny.res.rr.com [66.24.58.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 96DBE2222A; Wed, 14 Oct 2020 15:38:25 +0000 (UTC) Date: Wed, 14 Oct 2020 11:38:23 -0400 From: Steven Rostedt To: Qiujun Huang Cc: mingo@redhat.com, linux-kernel@vger.kernel.org Subject: Re: [PATCH] ring-buffer: Add rb_check_bpage in __rb_allocate_pages Message-ID: <20201014113823.4296521d@gandalf.local.home> In-Reply-To: <20201014151614.29804-1-hqjagain@gmail.com> References: <20201014151614.29804-1-hqjagain@gmail.com> X-Mailer: Claws Mail 3.17.3 (GTK+ 2.24.32; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 14 Oct 2020 23:16:14 +0800 Qiujun Huang wrote: > It may be better to check each page is aligned by 4 bytes. The 2 > least significant bits of the address will be used as flags. > > Signed-off-by: Qiujun Huang > --- > kernel/trace/ring_buffer.c | 11 +++++++---- > 1 file changed, 7 insertions(+), 4 deletions(-) > > diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c > index 93ef0ab6ea20..9dec7d58b177 100644 > --- a/kernel/trace/ring_buffer.c > +++ b/kernel/trace/ring_buffer.c > @@ -1420,7 +1420,8 @@ static int rb_check_pages(struct ring_buffer_per_cpu *cpu_buffer) > return 0; > } > > -static int __rb_allocate_pages(long nr_pages, struct list_head *pages, int cpu) > +static int __rb_allocate_pages(struct ring_buffer_per_cpu *cpu_buffer, > + long nr_pages, struct list_head *pages, int cpu) > { > struct buffer_page *bpage, *tmp; > bool user_thread = current->mm != NULL; > @@ -1464,6 +1465,8 @@ static int __rb_allocate_pages(long nr_pages, struct list_head *pages, int cpu) > if (!bpage) > goto free_pages; > > + rb_check_bpage(cpu_buffer, bpage); > + > Why add it here, and not just add this check to the scan in rb_check_pages()? -- Steve