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 7E3E7C433EF for ; Thu, 5 May 2022 13:00:31 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id A720C6B0071; Thu, 5 May 2022 09:00:30 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id A218B6B0073; Thu, 5 May 2022 09:00:30 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 8E8356B0074; Thu, 5 May 2022 09:00:30 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0011.hostedemail.com [216.40.44.11]) by kanga.kvack.org (Postfix) with ESMTP id 7C8EC6B0071 for ; Thu, 5 May 2022 09:00:30 -0400 (EDT) Received: from smtpin03.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay06.hostedemail.com (Postfix) with ESMTP id 45A1F2EF8A for ; Thu, 5 May 2022 13:00:30 +0000 (UTC) X-FDA: 79431698220.03.81DDADD Received: from mail-wr1-f42.google.com (mail-wr1-f42.google.com [209.85.221.42]) by imf19.hostedemail.com (Postfix) with ESMTP id 768171A00A7 for ; Thu, 5 May 2022 13:00:19 +0000 (UTC) Received: by mail-wr1-f42.google.com with SMTP id e24so6007323wrc.9 for ; Thu, 05 May 2022 06:00:25 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=EGukWjN41YXunuHxiJ6v8MoB3BMhKLGHT/yPujsOYE4=; b=Di4KSmN2FEodAD7lFMKM//ME8zqBRzDiFN9JSNNrXpGoZkzZRpwH7FzfEjSRcmbcfx lJtdemxD5INqyiVcGQ3nySkkngToLYeD3EHhvaVkl67QSkcnUwRzZ2kLQ1rycYIpenLE yqOx8R1S1HwvPK+keCmqRnR56l4fnqrndEFj+Sq2FUfNato0sftXAokYLucDAoKtvOxW Gco8rfwH7ieNa8ChBxegXLa4K0QixoM1FpAT0jgyC3slx3yQJ1KlVWNGklmMnWurMhyP KP8GFgQ+TWcoNuG7xShEeeiYVI5rfQrWx2uFNvlEO+rVxXd9E7jqC+9xWGLcvbzoe9L3 ilEw== 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:user-agent; bh=EGukWjN41YXunuHxiJ6v8MoB3BMhKLGHT/yPujsOYE4=; b=Wgb3BS/wI6H4hIRq6esAubQJTv/0TLFIhMjlz4QFaWv3GO19+cl4rkumvGTdNzgzJ9 SnAZrU18AgsPYyjjE2NQfTaCpqBJMmgFpmxFg0DxFZaFt+YuSuRGQya7LpSMQHOlA0iz qKaSutd7tQrmOTA5qHKri/G16iTSyI6rRA9Vf7UtzzzNPQ8k2mxWm1KMeYr5j+aRjA6n PT/e7jTSg01SJmKhjUIAX53kMFBLsRmChPhyxhRAjeAKwTmqpdNpXLQIQ7fSSXe9emvw 7QjUrcLoe/hQr5FIbEM1uoNkOAWwTrpYpD46NKI0pGpdHr9vWQP7fyP8QydjgueSYHwc tlkw== X-Gm-Message-State: AOAM531AAn6Q/ucb9ZJiT44h1Nae5tL+RwjmuDImQ9xa5poYTiv31GnS LbDHpShmwYqaVL0dxLCKuoobGg== X-Google-Smtp-Source: ABdhPJxjtASToxRPCpk4uJFbbWje3gNccF30PaUNbYTd7HVydvY5Fa4RgqOnAT2p8ElPqwb22oVDAQ== X-Received: by 2002:adf:ecc7:0:b0:20a:dba3:a516 with SMTP id s7-20020adfecc7000000b0020adba3a516mr20355168wro.143.1651755624061; Thu, 05 May 2022 06:00:24 -0700 (PDT) Received: from elver.google.com ([2a00:79e0:15:13:786b:6d06:626e:af02]) by smtp.gmail.com with ESMTPSA id k9-20020adfe3c9000000b0020c5253d8eesm1209895wrm.58.2022.05.05.06.00.23 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 05 May 2022 06:00:23 -0700 (PDT) Date: Thu, 5 May 2022 15:00:18 +0200 From: Marco Elver To: Hyeonggon Yoo <42.hyeyoo@gmail.com> Cc: Muchun Song , Alexander Potapenko , Dmitry Vyukov , Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v4] mm/kfence: reset PG_slab and memcg_data before freeing __kfence_pool Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/2.1.4 (2021-12-11) Authentication-Results: imf19.hostedemail.com; dkim=pass header.d=google.com header.s=20210112 header.b=Di4KSmN2; dmarc=pass (policy=reject) header.from=google.com; spf=pass (imf19.hostedemail.com: domain of elver@google.com designates 209.85.221.42 as permitted sender) smtp.mailfrom=elver@google.com X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 768171A00A7 X-Rspam-User: X-Stat-Signature: 46umhti55sd5yr9xcxpoop4nmbwuo76c X-HE-Tag: 1651755619-255660 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 09:45PM +0900, Hyeonggon Yoo wrote: > When kfence fails to initialize kfence pool, it frees the pool. > But it does not reset memcg_data and PG_slab flag. > > Below is a BUG because of this. Let's fix it by resetting memcg_data > and PG_slab flag 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 Thank you both. > --- > > v3 -> v4: > - Use struct slab instead of folio and reset memcg_data and > clear PG_slab only if PG_slab flag is set (virt_to_slab() != NULL). > > Thanks Muchun. Now it looks much better and still works. > > - Remove Reviewed-by: tags as the code changed. Please add new > one if the patch still looks good to you. > > mm/kfence/core.c | 10 ++++++++++ > 1 file changed, 10 insertions(+) > > diff --git a/mm/kfence/core.c b/mm/kfence/core.c > index a203747ad2c0..58dfac1828ce 100644 > --- a/mm/kfence/core.c > +++ b/mm/kfence/core.c > @@ -642,6 +642,16 @@ 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 slab *slab = virt_to_slab(p); > + > + if (!slab) > + continue; > +#ifdef CONFIG_MEMCG > + slab->memcg_data = 0; > +#endif > + __folio_clear_slab(slab_folio(slab)); > + } > memblock_free_late(__pa(addr), KFENCE_POOL_SIZE - (addr - (unsigned long)__kfence_pool)); > __kfence_pool = NULL; > return false; > -- > 2.32.0