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 B41F9C433EF for ; Thu, 5 May 2022 07:12:53 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id C99216B0071; Thu, 5 May 2022 03:12:52 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id C49D76B0073; Thu, 5 May 2022 03:12:52 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id B11F16B0074; Thu, 5 May 2022 03:12:52 -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 9D8996B0071 for ; Thu, 5 May 2022 03:12:52 -0400 (EDT) Received: from smtpin19.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay06.hostedemail.com (Postfix) with ESMTP id 7025C2CEE8 for ; Thu, 5 May 2022 07:12:52 +0000 (UTC) X-FDA: 79430822184.19.C2BFA80 Received: from mail-yb1-f172.google.com (mail-yb1-f172.google.com [209.85.219.172]) by imf06.hostedemail.com (Postfix) with ESMTP id 1AAA1180095 for ; Thu, 5 May 2022 07:12:49 +0000 (UTC) Received: by mail-yb1-f172.google.com with SMTP id m128so6155558ybm.5 for ; Thu, 05 May 2022 00:12:51 -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=lfIOkRZ6twwlsVq7LPAuc7rDKCIGPs8QeABSEQr/fQs=; b=H7H2f3q0+qqzRnTvoXnZweOxqGU80TTLxMshqe+rVobEvVXkJPNQwH88IjPYhPFAZW qCfLwAwNjNN1nmJZTJ1rBtogddVOqLPeq8LVBHwpJEJyOspd0H/SV3ihJ09fmr5hNd8V NiIjZ2kTydUQN+1xM5zo8rH+aXlPEq0lh8daLYLq+YoS1eHkHCZQvg+PYZk/dLDheGML 2sk9dlTD2cfGuxMayM9Z7i6eR2mvxqLxsmX8/4cZuNbdFw/uc6u2D9cJs1UmL2M493FA C7PKU6FUoP2KUGXzhMshB3a4YNITUloo25lV0OTA0Ps/83WM+7Ph+xEAsY9hl+rVPV1l ykMg== 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=lfIOkRZ6twwlsVq7LPAuc7rDKCIGPs8QeABSEQr/fQs=; b=LmTJClPmo/mi3MCXkU7EiCGyEWOpqEGBd1sVPDuGTlUnBEQIFImReit9qz4Pk4bYa/ Kue9n5hQUv0sEacGsPSpKpxyKXiz7ROVW4xQvhInoT0KBMlQFKZyHU91TuLPYnl13zOZ KdCu5svfwcCLEdNn0NfZ5xmdLEsrt3mrZ2xCYR4gFYBuL/PAzr3mHZHYCVYt4C0mwZqk 7R0XqrsL9EEX8bnAiCSExaiiabd/aVGSEc+/Din2MMT+f6hqw3pTDK1plzEFdfWiPQI8 udJi0MWwfvPnxnqdnEzwH+Ly6Ah3oX70C3E2JJmpGAUgDIuI69D1k6eynNJ7kX6o7DiR EDcQ== X-Gm-Message-State: AOAM532djSxEwKrpoUgkOhjiFXt8fPE910PUxEXJCXDJQP7FS5eGv/m/ 0Vg2/3CLSybYaxDhbDxjmREvSn2oRKEhQT3iaXuOqg== X-Google-Smtp-Source: ABdhPJxjJOcBPijJ+UuYDZbSy+0Q+ExeJS8fHz1umGyJQhtJVG0eLOe7bhN2Zp5Oeiew6kT5WeRnFin143BDpNcOwew= X-Received: by 2002:a25:3623:0:b0:649:e6fd:2b54 with SMTP id d35-20020a253623000000b00649e6fd2b54mr8839710yba.625.1651734771001; Thu, 05 May 2022 00:12:51 -0700 (PDT) MIME-Version: 1.0 References: <20220505070105.1835745-1-42.hyeyoo@gmail.com> In-Reply-To: <20220505070105.1835745-1-42.hyeyoo@gmail.com> From: Marco Elver Date: Thu, 5 May 2022 09:12:14 +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" X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 1AAA1180095 X-Stat-Signature: iuwoabdwc5wtaxpdzgj6qh6uwointbic X-Rspam-User: Authentication-Results: imf06.hostedemail.com; dkim=pass header.d=google.com header.s=20210112 header.b=H7H2f3q0; spf=pass (imf06.hostedemail.com: domain of elver@google.com designates 209.85.219.172 as permitted sender) smtp.mailfrom=elver@google.com; dmarc=pass (policy=reject) header.from=google.com X-HE-Tag: 1651734769-385543 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, 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") > 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 >