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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id B0784C433F5 for ; Sat, 12 Mar 2022 02:10:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229992AbiCLCLQ (ORCPT ); Fri, 11 Mar 2022 21:11:16 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44350 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229447AbiCLCLP (ORCPT ); Fri, 11 Mar 2022 21:11:15 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4AF4F4FC7F; Fri, 11 Mar 2022 18:10:11 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id DB21AB82C0F; Sat, 12 Mar 2022 02:10:09 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 45F6EC340E9; Sat, 12 Mar 2022 02:10:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1647051008; bh=bp069JGN4ocK6yuNHpcDkHggg5EUw4G/koG2EZ6uGZw=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=WHcMISdP/M7cIEW7D6QoAw8quonpsAfRVpqaRZBmAv397rAdx1X+wHl570R8VKrEX UW+98a/5yJAImtgEfXqqhZ5IDrPSVYfji9B7fLD0/TkF2XUcBsw0J/vilNlz8zAAHl oBR3cHjp5zHzrx4YZIe+Z7vwvmuuGMUdl6RrsaRA6WXTI3WJh7NQLGLm5EoJy0OTAi AUFFzXEtUqIRb5VUjKedWir4xliYOECFrn+psx+cs+dG/naS76omeJFqIa0vUUoF88 wfe5Tj5191F2WV4JKjgJDhYxSrHcs/C8TbXBSkhrxjyvI5EZAxmS6vKdj+vN1v1JAL T0VyjeuBXdpnA== Date: Sat, 12 Mar 2022 11:10:04 +0900 From: Masami Hiramatsu To: Steven Rostedt Cc: LKML , Beau Belgrave , Anders Roxell , Masami Hiramatsu , Linux Trace Devel Subject: Re: [PATCH] tracing/user_events: Use alloc_pages instead of kzalloc() for register pages Message-Id: <20220312111004.a199b41e036fe79da05b84f6@kernel.org> In-Reply-To: <20220311190457.0345eeb2@gandalf.local.home> References: <20220311190457.0345eeb2@gandalf.local.home> X-Mailer: Sylpheed 3.7.0 (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-trace-devel@vger.kernel.org On Fri, 11 Mar 2022 19:04:57 -0500 Steven Rostedt wrote: > From: "Steven Rostedt (Google)" > > kzalloc virtual addresses do not work with SetPageReserved, use the actual > page virtual addresses instead via alloc_pages. Indeed. kzalloc allocates a slab object, we need a page. Acked-by: Masami Hiramatsu Thank you, > > The issue is reported when booting with user_events and > DEBUG_VM_PGFLAGS=y. > > Also make the number of events based on the ORDER. > > Link: https://lore.kernel.org/all/CADYN=9+xY5Vku3Ws5E9S60SM5dCFfeGeRBkmDFbcxX0ZMoFing@mail.gmail.com/ > Link: https://lore.kernel.org/all/20220311223028.1865-1-beaub@linux.microsoft.com/ > > Cc: Beau Belgrave > Reported-by: Anders Roxell > Signed-off-by: Steven Rostedt (Google) > --- > kernel/trace/trace_events_user.c | 14 ++++++++------ > 1 file changed, 8 insertions(+), 6 deletions(-) > > diff --git a/kernel/trace/trace_events_user.c b/kernel/trace/trace_events_user.c > index 4febc1d6ae72..e10ad057e797 100644 > --- a/kernel/trace/trace_events_user.c > +++ b/kernel/trace/trace_events_user.c > @@ -30,9 +30,10 @@ > > /* > * Limits how many trace_event calls user processes can create: > - * Must be multiple of PAGE_SIZE. > + * Must be a power of two of PAGE_SIZE. > */ > -#define MAX_PAGES 1 > +#define MAX_PAGE_ORDER 0 > +#define MAX_PAGES (1 << MAX_PAGE_ORDER) > #define MAX_EVENTS (MAX_PAGES * PAGE_SIZE) > > /* Limit how long of an event name plus args within the subsystem. */ > @@ -1622,16 +1623,17 @@ static void set_page_reservations(bool set) > > static int __init trace_events_user_init(void) > { > + struct page *pages; > int ret; > > /* Zero all bits beside 0 (which is reserved for failures) */ > bitmap_zero(page_bitmap, MAX_EVENTS); > set_bit(0, page_bitmap); > > - register_page_data = kzalloc(MAX_EVENTS, GFP_KERNEL); > - > - if (!register_page_data) > + pages = alloc_pages(GFP_KERNEL | __GFP_ZERO, MAX_PAGE_ORDER); > + if (!pages) > return -ENOMEM; > + register_page_data = page_address(pages); > > set_page_reservations(true); > > @@ -1640,7 +1642,7 @@ static int __init trace_events_user_init(void) > if (ret) { > pr_warn("user_events could not register with tracefs\n"); > set_page_reservations(false); > - kfree(register_page_data); > + __free_pages(pages, MAX_PAGE_ORDER); > return ret; > } > > -- > 2.34.1 > -- Masami Hiramatsu