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=-21.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING, SPF_HELO_NONE,SPF_PASS 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 0CA28C433DB for ; Tue, 30 Mar 2021 03:56:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DB75561954 for ; Tue, 30 Mar 2021 03:56:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231622AbhC3D4O (ORCPT ); Mon, 29 Mar 2021 23:56:14 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:28783 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231424AbhC3Dzt (ORCPT ); Mon, 29 Mar 2021 23:55:49 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1617076548; 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: in-reply-to:in-reply-to:references:references; bh=WgugrUzLoQTlg1TeffveEjnxJmaQPE4uFnKyCgzgdIQ=; b=H/ZyOPiAF9Oi73UcH9LQuPuFd5rUVxIwC/17zYTYumONldeEXmhj54THv2PKjZs56tSXyV HFxA8+5cH+J8sSVzhCmZIAVpuxPGHlOCTWZNymZouBTSt6azytMSpQrTc0vEukFrDRLQIn pkG/4uFIeWOkz77DvLZa/xEX1inq9Ck= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-415-AUXuHJP0PrmDFoBBTGnclA-1; Mon, 29 Mar 2021 23:55:45 -0400 X-MC-Unique: AUXuHJP0PrmDFoBBTGnclA-1 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 mimecast-mx01.redhat.com (Postfix) with ESMTPS id AD226501FB; Tue, 30 Mar 2021 03:55:43 +0000 (UTC) Received: from T590 (ovpn-12-129.pek2.redhat.com [10.72.12.129]) by smtp.corp.redhat.com (Postfix) with ESMTPS id E45095D6D3; Tue, 30 Mar 2021 03:55:36 +0000 (UTC) Date: Tue, 30 Mar 2021 11:55:31 +0800 From: Ming Lei To: Su Yue Cc: Jens Axboe , linux-block@vger.kernel.org, Christoph Hellwig , linux-kernel@vger.kernel.org Subject: Re: [PATCH 2/2] blktrace: limit allowed total trace buffer size Message-ID: References: <20210323081440.81343-1-ming.lei@redhat.com> <20210323081440.81343-3-ming.lei@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On Tue, Mar 30, 2021 at 10:57:04AM +0800, Su Yue wrote: > > On Tue 23 Mar 2021 at 16:14, Ming Lei wrote: > > > On some ARCHs, such as aarch64, page size may be 64K, meantime there may > > be lots of CPU cores. relay_open() needs to allocate pages on each CPU > > blktrace, so easily too many pages are taken by blktrace. For example, > > on one ARM64 server: 224 CPU cores, 16G RAM, blktrace finally got > > allocated 7GB in case of 'blktrace -b 8192' which is used by > > device-mapper > > test suite[1]. This way could cause OOM easily. > > > > Fix the issue by limiting max allowed pages to be 1/8 of > > totalram_pages(). > > > > [1] https://github.com/jthornber/device-mapper-test-suite.git > > > > Signed-off-by: Ming Lei > > --- > > kernel/trace/blktrace.c | 32 ++++++++++++++++++++++++++++++++ > > 1 file changed, 32 insertions(+) > > > > diff --git a/kernel/trace/blktrace.c b/kernel/trace/blktrace.c > > index c221e4c3f625..8403ff19d533 100644 > > --- a/kernel/trace/blktrace.c > > +++ b/kernel/trace/blktrace.c > > @@ -466,6 +466,35 @@ static void blk_trace_setup_lba(struct blk_trace > > *bt, > > } > > } > > > > +/* limit total allocated buffer size is <= 1/8 of total pages */ > > +static void validate_and_adjust_buf(struct blk_user_trace_setup *buts) > > +{ > > + unsigned buf_size = buts->buf_size; > > + unsigned buf_nr = buts->buf_nr; > > + unsigned long max_allowed_pages = totalram_pages() >> 3; > > + unsigned long req_pages = PAGE_ALIGN(buf_size * buf_nr) >> PAGE_SHIFT; > > + > > + if (req_pages * num_online_cpus() <= max_allowed_pages) > > + return; > > + > > + req_pages = DIV_ROUND_UP(max_allowed_pages, num_online_cpus()); > > + > > + if (req_pages == 0) { > > + buf_size = PAGE_SIZE; > > + buf_nr = 1; > > + } else { > > + buf_size = req_pages << PAGE_SHIFT / buf_nr; > > > Should it be: > buf_size = (req_pages << PAGE_SHIFT) / buf_nr; > ? > The priority of '<<' is lower than '/', right? :) Good catch, thanks! -- Ming