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 82C50C433EF for ; Thu, 5 May 2022 11:33:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1355396AbiEELhX (ORCPT ); Thu, 5 May 2022 07:37:23 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37878 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235500AbiEELhV (ORCPT ); Thu, 5 May 2022 07:37:21 -0400 Received: from mail-pj1-x1031.google.com (mail-pj1-x1031.google.com [IPv6:2607:f8b0:4864:20::1031]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B2C5C25C44 for ; Thu, 5 May 2022 04:33:42 -0700 (PDT) Received: by mail-pj1-x1031.google.com with SMTP id r9so3940096pjo.5 for ; Thu, 05 May 2022 04:33:42 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=kmuFsmMbScXqNpJKevjdoCTx8wEqO5EzwJvGHLtPy5Y=; b=TYH0Dyz10TR6mI8byBxOTAE/d4FWaSoLnmjYYE6gNf9TxRn0/7YsDYgoWircT5IP0N 7Jf4G/6xEWIRlwurNKxK9t7OvbXgxtX6PdCEwWWffrjqnMDX7rdHpb4uUf1P3ybF2Wpt ZuWxdOOpvE2Uf8+aUUUl2SGqzsQP3bocH20H5GBdfHwrZlpqHpy6GklQ5jidn2hsZ10h 76Dov4K3HIN94fEKUEOqxsmQw2KL0OGlSS/Z/umWKEw8tinz3f+4xPxKYLyTksG2H8y8 IlrZ6vwlR92OTSIeR56kWXSn8v88BaNrFCoHOfnTmlBiD2IeIEWjPU06TxuZLh4IRLOg KgbQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=kmuFsmMbScXqNpJKevjdoCTx8wEqO5EzwJvGHLtPy5Y=; b=tiQqo4WgtehgAhuQZTgshM7I+ocfOi29Cny4HP/8RMxesU+lYyQhZGwcz+0OCz6Puj nLDkwxpt1MtaLGOHfTvNxNXu0MItwsuk60jB/i0AlFpyoRpAfPeTA/mFS7N+oHMPCCjj WcEZdMwW03tjDpFQfhz6iEGBb5JISPkMtD66VepqEy98aev/dWbfjGpRlqXzNpXxMKFs EaGU9mWsVl4pDjO9O8iNfCUuiT3nUdaiXlHwDc72E9NRWXzYGsvmJLcfLl1cP0c1poCM 6HMG8S+RtAeh+VdtEttyaTHKe2bX0hQEyGyhjgVlkIqI/4tqBfkkJ+LBe8BGp8qiWwEC ihFw== X-Gm-Message-State: AOAM530Pl6aS+9FCywblz34waOPOLsxKT5+Pig9ljV89riDkI8chzwG0 SjaN5R5KsobeH4EKJNSPGQsJQXp5jbM= X-Google-Smtp-Source: ABdhPJzmigFknhavmOH0RXnf30nGm1L9Uv6+t0G3al3oC8qiPS2XWcxMg3ZRyAUvfOD5N/M15+5wXQ== X-Received: by 2002:a17:903:2d0:b0:14d:8a8d:cb1 with SMTP id s16-20020a17090302d000b0014d8a8d0cb1mr26801364plk.50.1651750422195; Thu, 05 May 2022 04:33:42 -0700 (PDT) Received: from hyeyoo ([114.29.24.243]) by smtp.gmail.com with ESMTPSA id 7-20020a17090a1a0700b001dbf2aac185sm1257143pjk.1.2022.05.05.04.33.39 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 05 May 2022 04:33:41 -0700 (PDT) Date: Thu, 5 May 2022 20:33:36 +0900 From: Hyeonggon Yoo <42.hyeyoo@gmail.com> To: Muchun Song Cc: Alexander Potapenko , Marco Elver , Dmitry Vyukov , Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v3] mm/kfence: reset PG_slab and memcg_data before freeing __kfence_pool Message-ID: References: <20220505073920.1880661-1-42.hyeyoo@gmail.com> <20220505101337.1997819-1-42.hyeyoo@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, May 05, 2022 at 06:54:18PM +0800, Muchun Song wrote: > On Thu, May 05, 2022 at 07:13:37PM +0900, Hyeonggon Yoo wrote: > > When kfence fails to initialize kfence pool, it frees the pool. > > But it does not reset PG_slab flag and memcg_data of struct page. > > > > Below is a BUG because of this. Let's fix it by resetting PG_slab > > and memcg_data before free. > > > > [ 0.089149] BUG: Bad page state in process swapper/0 pfn:3d8e06 > > [ 0.089149] page:ffffea46cf638180 refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x3d8e06 > > [ 0.089150] memcg:ffffffff94a475d1 > > [ 0.089150] flags: 0x17ffffc0000200(slab|node=0|zone=2|lastcpupid=0x1fffff) > > [ 0.089151] raw: 0017ffffc0000200 ffffea46cf638188 ffffea46cf638188 0000000000000000 > > [ 0.089152] raw: 0000000000000000 0000000000000000 00000000ffffffff ffffffff94a475d1 > > [ 0.089152] page dumped because: page still charged to cgroup > > [ 0.089153] Modules linked in: > > [ 0.089153] CPU: 0 PID: 0 Comm: swapper/0 Tainted: G B W 5.18.0-rc1+ #965 > > [ 0.089154] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.14.0-2 04/01/2014 > > [ 0.089154] Call Trace: > > [ 0.089155] > > [ 0.089155] dump_stack_lvl+0x49/0x5f > > [ 0.089157] dump_stack+0x10/0x12 > > [ 0.089158] bad_page.cold+0x63/0x94 > > [ 0.089159] check_free_page_bad+0x66/0x70 > > [ 0.089160] __free_pages_ok+0x423/0x530 > > [ 0.089161] __free_pages_core+0x8e/0xa0 > > [ 0.089162] memblock_free_pages+0x10/0x12 > > [ 0.089164] memblock_free_late+0x8f/0xb9 > > [ 0.089165] kfence_init+0x68/0x92 > > [ 0.089166] start_kernel+0x789/0x992 > > [ 0.089167] x86_64_start_reservations+0x24/0x26 > > [ 0.089168] x86_64_start_kernel+0xa9/0xaf > > [ 0.089170] secondary_startup_64_no_verify+0xd5/0xdb > > [ 0.089171] > > > > Fixes: 0ce20dd84089 ("mm: add Kernel Electric-Fence infrastructure") > > Fixes: 8f0b36497303 ("mm: kfence: fix objcgs vector allocation") > > Signed-off-by: Hyeonggon Yoo <42.hyeyoo@gmail.com> > > Reviewed-by: Marco Elver > > Reviewed-by: Muchun Song > > --- > > > > v2 -> v3: > > - Add Reviewed-by: tags from Marco and Muchun. Thanks! > > - Initialize folio where it is defined. > > > > mm/kfence/core.c | 8 ++++++++ > > 1 file changed, 8 insertions(+) > > > > diff --git a/mm/kfence/core.c b/mm/kfence/core.c > > index a203747ad2c0..b7d3a9667f00 100644 > > --- a/mm/kfence/core.c > > +++ b/mm/kfence/core.c > > @@ -642,6 +642,14 @@ static bool __init kfence_init_pool_early(void) > > * fails for the first page, and therefore expect addr==__kfence_pool in > > * most failure cases. > > */ > > + for (char *p = (char *)addr; p < __kfence_pool + KFENCE_POOL_SIZE; p += PAGE_SIZE) { > > + struct folio *folio = virt_to_folio(p); > > + > > After more thinking, I think it is better to use 'struct slab *' > to define a local variable since we already use this struct > throughout slab core. What do you think? > I think that may not be better. In the code we're freeing folios (so not going to reuse it again in slab/kfence). And it may not be Slab depending on why kfence_init_pool() failed. > Thanks. > > > + __folio_clear_slab(folio); > > +#ifdef CONFIG_MEMCG > > + folio->memcg_data = 0; > > +#endif > > + } > > memblock_free_late(__pa(addr), KFENCE_POOL_SIZE - (addr - (unsigned long)__kfence_pool)); > > __kfence_pool = NULL; > > return false; > > -- > > 2.32.0 > > > > -- Thanks, Hyeonggon