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 F27A9C433F5 for ; Thu, 5 May 2022 07:20:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1343656AbiEEHXs (ORCPT ); Thu, 5 May 2022 03:23:48 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59778 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236406AbiEEHXr (ORCPT ); Thu, 5 May 2022 03:23:47 -0400 Received: from mail-yw1-x1130.google.com (mail-yw1-x1130.google.com [IPv6:2607:f8b0:4864:20::1130]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 81A5F3D1FF for ; Thu, 5 May 2022 00:20:08 -0700 (PDT) Received: by mail-yw1-x1130.google.com with SMTP id 00721157ae682-2f16645872fso39161047b3.4 for ; Thu, 05 May 2022 00:20:08 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=+4pwyCdtrN8skjkL3vLrOUo2V3SJhrVEC+DpJFR51tI=; b=h8tmaFlRX8/Tss0bkURxHOUEOLsbjRHmcdCam7Byv5CvV5wpZ8uc0/lEegLvga7O9T srDENjfNKgZ2j+yUIyopyryfabK6A5EfpnumfHgGXN2Z7qldNA2Vl3ZeqC4SJwMAraWY QSycz28a/w7qlp20rcCFYmvS74J+z+uLzrmgvqEjPWmX/IfC58WXclVsIKpuz+p+lDWf U8Lx1iTi1GmC90VgOK3OGxXimXP6OpuPDsbjHiDbvD5lCjPiNxMK/kvMCEkqPg2o+Liz Ab57k+HBhCQKsaE9ESVF3Fl51tN2qsNlJMeq91Tw8XPIH4eQMNMa6nNSIghe7vmT+C+B /cbg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=+4pwyCdtrN8skjkL3vLrOUo2V3SJhrVEC+DpJFR51tI=; b=hPTT07vuaiYU1uQACcFbUulmM6QYPQsP0IwgaTZGoA1yNxawoOOxAK3EVB1SJdKFtV sS7z1sxDLmaJFTfNU0lCBMAx7CDM+InhN36BDx4AJi/Xcg8UPd2p67oZp0m2KaUnZqVs VRq8gcqJw288I2tXALUB0jYulfFJi+eqAwuCE13YN2ib4HpCHDXvwKSBhJfEJDqf6koo svbHTU4t588j9aODRe+/eZ2QsSGFvyaH71HFkCbVQZqxJ9W2p/ANfSurpSuLkheiRYRd 4xBLcSNn0MRBkJHQHla22DIf2TcOlI/DuU9UOea539XzMJc/2g5cP4DhDhyjsArPSZjf AuSQ== X-Gm-Message-State: AOAM5311BmogBTpdl2Kh1TLxUtr2EcSrTETuUaIrtfBdW2hirZ9aI4hN VLRVtCLJ5z/Rkcwvu5OISG8mnsDveakMtL70yRbkTA== X-Google-Smtp-Source: ABdhPJywLXQgFtVLlJSm6LvNWhnseLHqOe2Yo9wmkm5Fl9mdjiJiLCR/gHb1szDME1GXMKPYqZArn7fCDBMHSqsjjXY= X-Received: by 2002:a81:4e83:0:b0:2f8:f7d3:2c71 with SMTP id c125-20020a814e83000000b002f8f7d32c71mr18383971ywb.264.1651735207601; Thu, 05 May 2022 00:20:07 -0700 (PDT) MIME-Version: 1.0 References: <20220505070105.1835745-1-42.hyeyoo@gmail.com> In-Reply-To: From: Marco Elver Date: Thu, 5 May 2022 09:19:31 +0200 Message-ID: Subject: Re: [PATCH] mm/kfence: reset PG_slab and memcg_data before freeing __kfence_pool To: Hyeonggon Yoo <42.hyeyoo@gmail.com>, Muchun Song Cc: Alexander Potapenko , Dmitry Vyukov , Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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") ? > > 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); > > We're now using __folio_set_slab(), so I'm guessing this should be > __folio_clear_slab()? > > > + } > > memblock_free_late(__pa(addr), KFENCE_POOL_SIZE - (addr - (unsigned long)__kfence_pool)); > > __kfence_pool = NULL; > > return false; > > -- > > 2.32.0 > >