From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752140AbYLRMsc (ORCPT ); Thu, 18 Dec 2008 07:48:32 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751364AbYLRMsV (ORCPT ); Thu, 18 Dec 2008 07:48:21 -0500 Received: from mx2.mail.elte.hu ([157.181.151.9]:45056 "EHLO mx2.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751361AbYLRMsV (ORCPT ); Thu, 18 Dec 2008 07:48:21 -0500 Date: Thu, 18 Dec 2008 13:48:03 +0100 From: Ingo Molnar To: Lai Jiangshan Cc: Steven Rostedt , Linux Kernel Mailing List Subject: Re: [PATCH] ring_bufer: fix BUF_PAGE_SIZE Message-ID: <20081218124803.GA31763@elte.hu> References: <4948CADF.6050205@cn.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4948CADF.6050205@cn.fujitsu.com> User-Agent: Mutt/1.5.18 (2008-05-17) X-ELTE-VirusStatus: clean X-ELTE-SpamScore: -1.5 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-1.5 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.2.3 -1.5 BAYES_00 BODY: Bayesian spam probability is 0 to 1% [score: 0.0000] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Lai Jiangshan wrote: > > impact: make BUF_PAGE_SIZE changeable. > > Except allocating/freeing page and the code using PAGE_MASK, > all code expect buffer_page's length is BUF_PAGE_SIZE. > > This patch make this behavior more concordant. > > Signed-off-by: Lai Jiangshan > --- > diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c > index 668bbb5..0cf6caf 100644 > --- a/kernel/trace/ring_buffer.c > +++ b/kernel/trace/ring_buffer.c > @@ -158,6 +158,10 @@ struct buffer_page { > void *page; /* Actual data page */ > }; > > +#define BUF_PAGE_ORDER 0 > +#define BUF_PAGE_SIZE (PAGE_SIZE << BUF_PAGE_ORDER) > +#define BUF_PAGE_MASK (~(BUF_PAGE_SIZE - 1)) > + > /* > * Also stolen from mm/slob.c. Thanks to Mathieu Desnoyers for pointing > * this issue out. > @@ -165,7 +169,7 @@ struct buffer_page { > static inline void free_buffer_page(struct buffer_page *bpage) > { > if (bpage->page) > - free_page((unsigned long)bpage->page); > + free_pages((unsigned long)bpage->page, BUF_PAGE_ORDER); hm, why? Non-order-0 allocations are pretty evil - why would we ever want to do them? Ingo