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 X-Spam-Level: X-Spam-Status: No, score=-5.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id EBC62C07E9B for ; Mon, 19 Jul 2021 12:24:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id CD0876115B for ; Mon, 19 Jul 2021 12:24:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236571AbhGSLnV (ORCPT ); Mon, 19 Jul 2021 07:43:21 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49798 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231290AbhGSLnU (ORCPT ); Mon, 19 Jul 2021 07:43:20 -0400 Received: from vulcan.natalenko.name (vulcan.natalenko.name [IPv6:2001:19f0:6c00:8846:5400:ff:fe0c:dfa0]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BC1E7C061574; Mon, 19 Jul 2021 04:39:55 -0700 (PDT) Received: from spock.localnet (unknown [151.237.229.131]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by vulcan.natalenko.name (Postfix) with ESMTPSA id E3F9CB3F5CE; Mon, 19 Jul 2021 14:23:56 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=natalenko.name; s=dkim-20170712; t=1626697437; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=K5psd6Gyst7jbmkEY35fCzySbAqC76tMvxDPI72IBLU=; b=cQTeim98LKn7CJbBdHfrCSWS7Gz5gbDejjwVrzQDQtHVIIhUvNWfN/pUwkdLmFNc0qLRSq XNvt1ZgCZ9ZRF3Abv0BoYfh0kaLDqY4ylhReu8cF9PxgYOfJwGQ0JQbelnzYns9x1wJUp2 SRhuOZDLzgWOuQUS6G0xqoXx+t4oJ/8= From: Oleksandr Natalenko To: Matthew Wilcox Cc: Miaohe Lin , Boqun Feng , Zhouyi Zhou , paulmck@kernel.org, linux-kernel , stable@vger.kernel.org, Chris Clayton , Chris Rankin , Josh Triplett , Steven Rostedt , Mathieu Desnoyers , Lai Jiangshan , Joel Fernandes , rcu , Andrew Morton , Linux-MM , "Huang, Ying" , gregkh@linuxfoundation.org Subject: Re: linux-5.13.2: warning from kernel/rcu/tree_plugin.h:359 Date: Mon, 19 Jul 2021 14:23:55 +0200 Message-ID: <2237123.PRLUojbHBq@natalenko.name> In-Reply-To: References: <5812280.fcLxn8YiTP@natalenko.name> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: rcu@vger.kernel.org On pond=C4=9Bl=C3=AD 19. =C4=8Dervence 2021 14:16:04 CEST Matthew Wilcox wr= ote: > On Mon, Jul 19, 2021 at 02:12:15PM +0200, Oleksandr Natalenko wrote: > > On pond=C4=9Bl=C3=AD 19. =C4=8Dervence 2021 14:08:37 CEST Miaohe Lin wr= ote: > > > On 2021/7/19 19:59, Oleksandr Natalenko wrote: > > > > On pond=C4=9Bl=C3=AD 19. =C4=8Dervence 2021 13:50:07 CEST Miaohe Li= n wrote: > > > >> On 2021/7/19 19:22, Matthew Wilcox wrote: > > > >>> On Mon, Jul 19, 2021 at 07:12:58PM +0800, Miaohe Lin wrote: > > > >>>> When in the commit 2799e77529c2a, we're using the percpu_ref to > > > >>>> serialize > > > >>>> against concurrent swapoff, i.e. there's percpu_ref inside > > > >>>> get_swap_device() instead of rcu_read_lock(). Please see commit > > > >>>> 63d8620ecf93 ("mm/swapfile: use percpu_ref to serialize against > > > >>>> concurrent swapoff") for detail. > > > >>>=20 > > > >>> Oh, so this is a backport problem. 2799e77529c2 was backported > > > >>> without > > > >>> its prerequisite 63d8620ecf93. Greg, probably best to just drop > > > >>=20 > > > >> Yes, they're posted as a patch set: > > > >>=20 > > > >> https://lkml.kernel.org/r/20210426123316.806267-1-linmiaohe@huawei= =2Eco > > > >> m > > > >>=20 > > > >>> 2799e77529c2 from all stable trees; the race described is not very > > > >>> important (swapoff vs reading a page back from that swap device). > > > >>> . > > > >>=20 > > > >> The swapoff races with reading a page back from that swap device > > > >> should > > > >> be > > > >> really uncommon as most users only do swapoff when the system is > > > >> going to > > > >> shutdown. > > > >>=20 > > > >> Sorry for the trouble! > > > >=20 > > > > git log --oneline v5.13..v5.13.3 --author=3D"Miaohe Lin" > > > > 11ebc09e50dc mm/zswap.c: fix two bugs in zswap_writeback_entry() > > > > 95d192da198d mm/z3fold: use release_z3fold_page_locked() to release > > > > locked > > > > z3fold page > > > > ccb7848e2344 mm/z3fold: fix potential memory leak in > > > > z3fold_destroy_pool() > > > > 9f7229c901c1 mm/huge_memory.c: don't discard hugepage if other > > > > processes > > > > are mapping it > > > > f13259175e4f mm/huge_memory.c: add missing read-only THP checking in > > > > transparent_hugepage_enabled() > > > > afafd371e7de mm/huge_memory.c: remove dedicated macro > > > > HPAGE_CACHE_INDEX_MASK a533a21b692f mm/shmem: fix shmem_swapin() ra= ce > > > > with swapoff > > > > c3b39134bbd0 swap: fix do_swap_page() race with swapoff > > > >=20 > > > > Do you suggest reverting "mm/shmem: fix shmem_swapin() race with > > > > swapoff" > > > > as well? > > >=20 > > > This patch also rely on its prerequisite 63d8620ecf93. I think we sho= uld > > > either revert any commit in this series or just backport the entire > > > series. > >=20 > > Then why not just pick up 2 more patches instead of dropping 2 patches. > > Greg, could you please make sure the whole series from [1] gets pulled? >=20 > Because none of these patches should have been backported in the first > place. It's just not worth the destabilisation. What about the rest then? git log --oneline v5.13..v5.13.3 -- mm/ | wc -l 18 Those look to be fixes, these ones too. =2D-=20 Oleksandr Natalenko (post-factum)