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 49589C76196 for ; Tue, 28 Mar 2023 13:04:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232507AbjC1NEk (ORCPT ); Tue, 28 Mar 2023 09:04:40 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41900 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232241AbjC1NEh (ORCPT ); Tue, 28 Mar 2023 09:04:37 -0400 X-Greylist: delayed 556 seconds by postgrey-1.37 at lindbergh.monkeyblade.net; Tue, 28 Mar 2023 06:03:52 PDT Received: from out-23.mta0.migadu.com (out-23.mta0.migadu.com [91.218.175.23]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 93C921BF9 for ; Tue, 28 Mar 2023 06:03:52 -0700 (PDT) Content-Type: text/plain; charset=utf-8 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1680008630; 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: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=V66ylQ1ow/PtGbySiIbSuU+rKhrjYB2OH7bPvmS2Z5E=; b=RAvirNNuQ9YV/tMSABybGE9T5wJP7bxOy8eucUIZyDsT23tztNKQn+3ARREhqry5rQ4vcy cApKQXt6Jk+1JMIQPXXCFSrqKKq2KtR0Kz1aAWeuIxSG/imLNTg9IrOLdLFcsNE1zVxgd9 oomNSscNdoujDV45gLBoC7aXPaSLe/E= MIME-Version: 1.0 Subject: Re: [PATCH 2/6] mm: kfence: check kfence pool size at building time X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Muchun Song In-Reply-To: Date: Tue, 28 Mar 2023 21:03:15 +0800 Cc: Muchun Song , glider@google.com, dvyukov@google.com, akpm@linux-foundation.org, jannh@google.com, sjpark@amazon.de, kasan-dev@googlegroups.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable Message-Id: References: <20230328095807.7014-1-songmuchun@bytedance.com> <20230328095807.7014-3-songmuchun@bytedance.com> To: Marco Elver X-Migadu-Flow: FLOW_OUT Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > On Mar 28, 2023, at 18:14, Marco Elver wrote: >=20 > On Tue, 28 Mar 2023 at 11:58, 'Muchun Song' via kasan-dev > wrote: >>=20 >> Check kfence pool size at building time to expose problem ASAP. >>=20 >> Signed-off-by: Muchun Song >> --- >> mm/kfence/core.c | 7 +++---- >> 1 file changed, 3 insertions(+), 4 deletions(-) >>=20 >> diff --git a/mm/kfence/core.c b/mm/kfence/core.c >> index de62a84d4830..6781af1dfa66 100644 >> --- a/mm/kfence/core.c >> +++ b/mm/kfence/core.c >> @@ -841,10 +841,9 @@ static int kfence_init_late(void) >> return -ENOMEM; >> __kfence_pool =3D page_to_virt(pages); >> #else >> - if (nr_pages > MAX_ORDER_NR_PAGES) { >> - pr_warn("KFENCE_NUM_OBJECTS too large for buddy = allocator\n"); >> - return -EINVAL; >> - } >> + BUILD_BUG_ON_MSG(get_order(KFENCE_POOL_SIZE) > MAX_ORDER, >> + "CONFIG_KFENCE_NUM_OBJECTS is too large for = buddy allocator"); >> + >=20 > It's perfectly valid to want to use KFENCE with a very large pool that > is initialized on boot, and simply sacrifice the ability to initialize > late. You are right. I didn=E2=80=99t realize this. Thanks=20 >=20 > Nack.