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 C3557C433EF for ; Thu, 5 May 2022 08:25:57 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 14B086B0071; Thu, 5 May 2022 04:25:57 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 0FA7A6B0073; Thu, 5 May 2022 04:25:57 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id F03B36B0074; Thu, 5 May 2022 04:25:56 -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 DF07D6B0071 for ; Thu, 5 May 2022 04:25:56 -0400 (EDT) Received: from smtpin29.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay08.hostedemail.com (Postfix) with ESMTP id AE54F20982 for ; Thu, 5 May 2022 08:25:56 +0000 (UTC) X-FDA: 79431006312.29.499E077 Received: from mail-yb1-f179.google.com (mail-yb1-f179.google.com [209.85.219.179]) by imf07.hostedemail.com (Postfix) with ESMTP id CEA6540083 for ; Thu, 5 May 2022 08:25:51 +0000 (UTC) Received: by mail-yb1-f179.google.com with SMTP id w17so6377213ybh.9 for ; Thu, 05 May 2022 01:25:56 -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=BKvsgWQUg0gMqeUR3q7cJz8EBr7iOI0sJ8d081w4vJA=; b=kGfS3bGeiu6lveuQ4kdgVfruOGv7LsufFzgu9lf9V0T2ClNwGvDnrvaQkeK2PA23E0 KC3TG3PugQIuIhH2FBbL+CwiX86nuxjvCbp2+P+wCG4BJKqIfdUiTkHwKn/cEbPh+5e3 9BPMW39rsRGeQ4Wp1Uxad6wfVYCYa+zFEdPOQSfS6IcrGt1fq/UQLdqTBXqyPQ/RirrW E14o7WY4KgkgPIPb8o+xighdKDYzbwQsabrDkFahK5prFANSmmuOO8oqXcn+nT/e5yHC VNVkuCWImM+/0ZfzczOUxVYm1ynprxg8TtFGrUpQ8X/mBc4zM8Em4doz3Q+JKXglsxHJ TnBQ== 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=BKvsgWQUg0gMqeUR3q7cJz8EBr7iOI0sJ8d081w4vJA=; b=oZxqtJ9APwiI9I5r4ogv+r1Jfov+UrF6A6mBxAYcKyCQ2XvVMw8fr7T1MjVTkp3k0o 5bVVFMiFgByuPcZg0/2YuzwXZ+rosVdsuNGj+EfzS6gKwwq/JMn29wFIT9QFwsaNDvFH qm22sFyU8SNbTpmdQTdxvP47M0T87FdBQjCSQqCwDB6ImmXGr1Vpa6BEHTbgq5aziOOf NqbEKOHnYLMKKTY5Gd5ER60Q0PFtn3gXwzWsC4tOO0e4NXYDmp9EEfWM8Q0JX2qawTpz MZB0OutkwSSHqEam1az5pFNnYagzSU+H/HBnvVXpfVsbNivANk2f3AkhaX/7xixWhu+S oKlg== X-Gm-Message-State: AOAM530TCwwet5xSiGzJwrD+4zn8N2rdOcs9micl/a6+ZV0/jK7Zr3Gk IrwMwoKFOfolu0qINgeKgKIbPaxyO3o4ijsaQQYxNQ== X-Google-Smtp-Source: ABdhPJxqgWPxdPhlMUn8kNuFyUpKwS8p9b4ea4HxMHa89K1lYxYllNEbIlUwBXh6PYFp3d5EDBwvUyhY9/TKJS1OH5I= X-Received: by 2002:a05:6902:1342:b0:648:a4d2:ff43 with SMTP id g2-20020a056902134200b00648a4d2ff43mr19964190ybu.425.1651739155360; Thu, 05 May 2022 01:25:55 -0700 (PDT) MIME-Version: 1.0 References: <20220505070105.1835745-1-42.hyeyoo@gmail.com> <20220505073920.1880661-1-42.hyeyoo@gmail.com> In-Reply-To: <20220505073920.1880661-1-42.hyeyoo@gmail.com> From: Marco Elver Date: Thu, 5 May 2022 10:25:18 +0200 Message-ID: Subject: Re: [PATCH v2] mm/kfence: reset PG_slab and memcg_data before freeing __kfence_pool To: Hyeonggon Yoo <42.hyeyoo@gmail.com> 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: CEA6540083 X-Stat-Signature: ptkhnkniijd5339hdanw1suuq4n9b8tt X-Rspam-User: Authentication-Results: imf07.hostedemail.com; dkim=pass header.d=google.com header.s=20210112 header.b=kGfS3bGe; spf=pass (imf07.hostedemail.com: domain of elver@google.com designates 209.85.219.179 as permitted sender) smtp.mailfrom=elver@google.com; dmarc=pass (policy=reject) header.from=google.com X-HE-Tag: 1651739151-623618 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 09:40, 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] > > 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 , with small comment below. > --- > > v1 -> v2: > - Use folio instead of page > - Add Fixes: tags > - Wrap #ifdef ~ #endif around folio->memcg_data = 0; > > mm/kfence/core.c | 9 +++++++++ > 1 file changed, 9 insertions(+) > > diff --git a/mm/kfence/core.c b/mm/kfence/core.c > index a203747ad2c0..bb1c6c489d0a 100644 > --- a/mm/kfence/core.c > +++ b/mm/kfence/core.c > @@ -642,6 +642,15 @@ 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; > + > + folio = virt_to_folio(p); Assign folio where it is defined above. Better to always initialize and guard against accidental uninit use in future. Thanks, -- Marco