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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 35994C433FE for ; Mon, 27 Sep 2021 07:54:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 113946113A for ; Mon, 27 Sep 2021 07:54:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233313AbhI0Hzk (ORCPT ); Mon, 27 Sep 2021 03:55:40 -0400 Received: from szxga02-in.huawei.com ([45.249.212.188]:21356 "EHLO szxga02-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233223AbhI0Hzh (ORCPT ); Mon, 27 Sep 2021 03:55:37 -0400 Received: from dggemv704-chm.china.huawei.com (unknown [172.30.72.56]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4HHvtG4Pw1zRG6N; Mon, 27 Sep 2021 15:49:42 +0800 (CST) Received: from dggpemm500001.china.huawei.com (7.185.36.107) by dggemv704-chm.china.huawei.com (10.3.19.47) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2308.8; Mon, 27 Sep 2021 15:53:48 +0800 Received: from [10.174.177.243] (10.174.177.243) by dggpemm500001.china.huawei.com (7.185.36.107) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2308.8; Mon, 27 Sep 2021 15:53:47 +0800 Subject: Re: [PATCH resend] slub: Add back check for free nonslab objects To: Vlastimil Babka , , Christoph Lameter , Pekka Enberg , David Rientjes , Joonsoo Kim , Andrew Morton , , References: <20210927021538.155991-1-wangkefeng.wang@huawei.com> <566f2009-6acf-4fb9-f7c0-edc1d6ce6561@suse.cz> From: Kefeng Wang Message-ID: <73b662cc-ab1f-b3bf-468a-4cd744e92d71@huawei.com> Date: Mon, 27 Sep 2021 15:53:47 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.7.0 MIME-Version: 1.0 In-Reply-To: <566f2009-6acf-4fb9-f7c0-edc1d6ce6561@suse.cz> Content-Type: text/plain; charset="utf-8"; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US X-Originating-IP: [10.174.177.243] X-ClientProxiedBy: dggems704-chm.china.huawei.com (10.3.19.181) To dggpemm500001.china.huawei.com (7.185.36.107) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2021/9/27 15:22, Vlastimil Babka wrote: > On 9/27/21 04:15, Kefeng Wang wrote: >> After commit ("f227f0faf63b slub: fix unreclaimable slab stat for bulk >> free"), the check for free nonslab page is replaced by VM_BUG_ON_PAGE, >> which only check with CONFIG_DEBUG_VM enabled, but this config may >> impact performance, so it only for debug. >> >> Commit ("0937502af7c9 slub: Add check for kfree() of non slab objects.") >> add the ability, which should be needed in any configs to catch the >> invalid free, they even could be potential issue, eg, memory corruption, >> use after free and double-free, so replace VM_BUG_ON_PAGE to WARN_ON, and >> add dump_page() to help use to debug the issue. > There are other situations in SLUB (such as with smaller allocations that > don't go directly to page allocator) where use after free and double-free > are undetected in non-debug configs, and it's expected that anyone debugging > them will enable slub_debug or even DEBUG_VM. Why should this special case > with nonslab pages be different? I want the check back in kfree, this one is used  widely in driver, and the probability of problem occurred is bigger in driver, especially in some out of tree drivers. > >> Signed-off-by: Kefeng Wang >> --- >> mm/slub.c | 3 ++- >> 1 file changed, 2 insertions(+), 1 deletion(-) >> >> diff --git a/mm/slub.c b/mm/slub.c >> index 3095b889fab4..555c2e6ccfca 100644 >> --- a/mm/slub.c >> +++ b/mm/slub.c >> @@ -3522,7 +3522,8 @@ static inline void free_nonslab_page(struct page *page, void *object) >> { >> unsigned int order = compound_order(page); >> >> - VM_BUG_ON_PAGE(!PageCompound(page), page); >> + if (WARN_ON(!PageCompound(page))) >> + dump_page(page, "invalid free nonslab page"); >> kfree_hook(object); >> mod_lruvec_page_state(page, NR_SLAB_UNRECLAIMABLE_B, -(PAGE_SIZE << order)); >> __free_pages(page, order); >> > . >