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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 09E4AC433F5 for ; Thu, 5 May 2022 11:33:44 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 3F6186B0071; Thu, 5 May 2022 07:33:44 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 3A4B16B0073; Thu, 5 May 2022 07:33:44 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 2453C6B0074; Thu, 5 May 2022 07:33:44 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0012.hostedemail.com [216.40.44.12]) by kanga.kvack.org (Postfix) with ESMTP id 158F56B0071 for ; Thu, 5 May 2022 07:33:44 -0400 (EDT) Received: from smtpin22.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay02.hostedemail.com (Postfix) with ESMTP id B80F02D71F for ; Thu, 5 May 2022 11:33:43 +0000 (UTC) X-FDA: 79431479526.22.B64036F Received: from mail-pl1-f178.google.com (mail-pl1-f178.google.com [209.85.214.178]) by imf21.hostedemail.com (Postfix) with ESMTP id 85F011C009D for ; Thu, 5 May 2022 11:33:37 +0000 (UTC) Received: by mail-pl1-f178.google.com with SMTP id i1so4112750plg.7 for ; Thu, 05 May 2022 04:33:43 -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=US10Y1NibXVEb4jS3Ck3/pIJFBPRHSpDH61plR85NTG80mI9AIOh4jSz2A2VaD71sY xRWd+rjgyGcz+3uCZfDgxk4IHasubu7HPrZ+k7PPmZq5nO8BJ7w4fUTIEQb5ePx3K6Tt DP3W0WGhjvjC9EdMJUPCZXylwfd0nd+ipdDszQlK1U86eVUPc/EfIQ+8ys4sEtJAFEcA PTJUbaL1YeHFRXPOuGrMUSR++Dzgq9SaninRm64ep6qXSE0kI88HfU2TINxivSBbPpXB Bj7jT065UMEcSgOZGphfSkvFmAfvvn6PCu0HVYckl+0EboqolHiYlMZyP8UGUGrR0lAf LaKg== X-Gm-Message-State: AOAM5307YpvTCqD1f97HoiL00vy71JRnwjuaA4NAiXj96r2gYdf9M+5Z y2bMwGsPpZtOcKUGTp9G8Bc= 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: X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: 85F011C009D X-Stat-Signature: zu5niiabyqbip5jcuttpaqag1d5ffca6 Authentication-Results: imf21.hostedemail.com; dkim=pass header.d=gmail.com header.s=20210112 header.b=TYH0Dyz1; dmarc=pass (policy=none) header.from=gmail.com; spf=pass (imf21.hostedemail.com: domain of 42.hyeyoo@gmail.com designates 209.85.214.178 as permitted sender) smtp.mailfrom=42.hyeyoo@gmail.com X-Rspam-User: X-HE-Tag: 1651750417-483012 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: 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