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 759C7C433F5 for ; Thu, 5 May 2022 07:27:46 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id DE8466B0071; Thu, 5 May 2022 03:27:45 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id D97966B0073; Thu, 5 May 2022 03:27:45 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id C38CF6B0074; Thu, 5 May 2022 03:27:45 -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 AE7B16B0071 for ; Thu, 5 May 2022 03:27:45 -0400 (EDT) Received: from smtpin21.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay07.hostedemail.com (Postfix) with ESMTP id 8A90120D79 for ; Thu, 5 May 2022 07:27:45 +0000 (UTC) X-FDA: 79430859690.21.6B73F7A Received: from mail-pl1-f173.google.com (mail-pl1-f173.google.com [209.85.214.173]) by imf15.hostedemail.com (Postfix) with ESMTP id 08237A0088 for ; Thu, 5 May 2022 07:27:35 +0000 (UTC) Received: by mail-pl1-f173.google.com with SMTP id i17so3610122pla.10 for ; Thu, 05 May 2022 00:27:44 -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=sdOJy9rnvDwfzvmnn6j6QC2/k4SprY6poljrhU6ERjM=; b=SH+mtnZULvwnaVfPcfukAFArBjFxn8qIN4CcPYpxa1rw8oKK8U+0XIaOdSv2j6hYHC ftdxMRAe9gn5EY8pm78hwxj4VnTgtIxV7vF1i/43NACuOxMpTX+Lyw3Ub/9otfAaT6d6 ayycK2sX8Z3NtK/A2ojQJVDhdvaNxP2Rlqsv989d52Qz+6R4l7odEGo62PDZB/YHAEvu dgj+OVHpkhQ5nzfMZ9i5be+A2UYiDxUCvJWT50h8eYLBRxKrUWdqX1rV52s5iMAps9Hm JXj0DHN+A4UpL8lASRHH29tzWBnMDUtPpAFVoD3elKHy5pA504Gpv1XcQuhCFMj6th7h NKqg== 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=sdOJy9rnvDwfzvmnn6j6QC2/k4SprY6poljrhU6ERjM=; b=DgZQptiOAq8gjXTBrHjQOQP29vnP1DOtZxrw6XSBOiIDpzlMBr1f/fm9zubJ+2egHD UGCZnPfSGBUlS8ddwyQYVqekFA3ABXmj9Leo8A0C71bH8MMwhAXxhF+BaIxTRdrMWO2p 6/tBV4FP5jPGLm6MV3WOGjDr0JD8l5sr2ujjY0NJlWZ0vLqWkFwT2mdarRVCMZXww0YQ 2JOj2BJfx7RkM+U5mEa/TjkRH56KTEZQeBFETR18Y5BS5/DwrrvYFwWj40ByqRFxceAP PAouldlNHYlDgHgTmoWK+jBVOSUukt/1JLuGi/k22QU5Aem/DxXFES364syj8X8p9A3r DE6g== X-Gm-Message-State: AOAM531bFqk4m1FME9ypShg9BM/7nFoF5sIauICvBmL+c3b/MLbfAmcA 8XZcUhbSc/X8b91DgF2wQlE= X-Google-Smtp-Source: ABdhPJx2PdxKwhBCD9gwdowDoR4lY3wzuXoyTmjGt6aTBhywjGErWD0KWXZwLPS4uSwt/24scXuo8w== X-Received: by 2002:a17:902:7c8c:b0:156:5651:1d51 with SMTP id y12-20020a1709027c8c00b0015656511d51mr25890593pll.107.1651735664051; Thu, 05 May 2022 00:27:44 -0700 (PDT) Received: from hyeyoo ([114.29.24.243]) by smtp.gmail.com with ESMTPSA id w10-20020a170902c78a00b0015e8d4eb223sm737930pla.109.2022.05.05.00.27.41 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 05 May 2022 00:27:43 -0700 (PDT) Date: Thu, 5 May 2022 16:27:38 +0900 From: Hyeonggon Yoo <42.hyeyoo@gmail.com> To: Marco Elver Cc: Muchun Song , Alexander Potapenko , Dmitry Vyukov , Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] mm/kfence: reset PG_slab and memcg_data before freeing __kfence_pool Message-ID: References: <20220505070105.1835745-1-42.hyeyoo@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Authentication-Results: imf15.hostedemail.com; dkim=pass header.d=gmail.com header.s=20210112 header.b=SH+mtnZU; spf=pass (imf15.hostedemail.com: domain of 42.hyeyoo@gmail.com designates 209.85.214.173 as permitted sender) smtp.mailfrom=42.hyeyoo@gmail.com; dmarc=pass (policy=none) header.from=gmail.com X-Rspam-User: X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 08237A0088 X-Stat-Signature: 74cuueccdaqw5i9gdym3h4i18r5e1fpr X-HE-Tag: 1651735655-960359 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 09:19:31AM +0200, Marco Elver wrote: > On Thu, 5 May 2022 at 09:12, Marco Elver wrote: > > > > On Thu, 5 May 2022 at 09:01, Hyeonggon Yoo <42.hyeyoo@gmail.com> 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] > > > > This is probably: > > > > Fixes: 0ce20dd84089 ("mm: add Kernel Electric-Fence infrastructure") > > Hmm, looking closer at the above BUG, I think it's > > Fixes: 8f0b36497303 ("mm: kfence: fix objcgs vector allocation") > > ? Marco, Thanks for comments. I think it fixes both because not clearing PG_slab also invokes a BUG. > > > > Signed-off-by: Hyeonggon Yoo <42.hyeyoo@gmail.com> > > > --- > > > mm/kfence/core.c | 7 +++++++ > > > 1 file changed, 7 insertions(+) > > > > > > diff --git a/mm/kfence/core.c b/mm/kfence/core.c > > > index a203747ad2c0..2ab3d473321e 100644 > > > --- a/mm/kfence/core.c > > > +++ b/mm/kfence/core.c > > > @@ -642,6 +642,13 @@ 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 page *page; > > > + > > > + page = virt_to_page(p); > > > > #ifdef CONFIG_MEMCG > > > > > + page->memcg_data = 0; > > > > #endif > > > > > + __ClearPageSlab(page); > > Ah, thanks! Will do in v2. > > We're now using __folio_set_slab(), so I'm guessing this should be > > __folio_clear_slab()? Right. Will do in v2. > > > > > + } > > > memblock_free_late(__pa(addr), KFENCE_POOL_SIZE - (addr - (unsigned long)__kfence_pool)); > > > __kfence_pool = NULL; > > > return false; > > > -- > > > 2.32.0 > > > -- Thanks, Hyeonggon