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 5CDB2C07E9B for ; Mon, 19 Jul 2021 11:59:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 351ED601FD for ; Mon, 19 Jul 2021 11:59:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231161AbhGSLSo (ORCPT ); Mon, 19 Jul 2021 07:18:44 -0400 Received: from vulcan.natalenko.name ([104.207.131.136]:55666 "EHLO vulcan.natalenko.name" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230493AbhGSLSo (ORCPT ); Mon, 19 Jul 2021 07:18:44 -0400 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 29CEDB3F506; Mon, 19 Jul 2021 13:59:22 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=natalenko.name; s=dkim-20170712; t=1626695962; 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=lEKGRenaAPW2gmTFyg57lWPQrt1Vqj2PhxfMAnpoKJU=; b=d7hajsSlNaqrqEWRUG0Ghtkzz+3EOXNYXRxp/oeBEBA+eE99YxWxRpSFDd4jBWG4X6y06I ADrN3O1atnVXbEsIvtzpvg53MakH1UoQjdWBG4LqW5mE+IqKMSz61I1C9XUMMHYeYKgMb3 XFYR7z+zaMV7h2ycTcjo3GdgR1bin+0= From: Oleksandr Natalenko To: Matthew Wilcox , Miaohe Lin Cc: 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 13:59:20 +0200 Message-ID: <2145858.R0O0FObHBN@natalenko.name> In-Reply-To: <8058e175-cec5-c243-6499-c1cd4e3c8605@huawei.com> References: <8058e175-cec5-c243-6499-c1cd4e3c8605@huawei.com> 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 13:50:07 CEST Miaohe Lin 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 serial= ize > >> 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.com >=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! 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= =20 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 ar= e=20 mapping it f13259175e4f mm/huge_memory.c: add missing read-only THP checking in=20 transparent_hugepage_enabled() afafd371e7de mm/huge_memory.c: remove dedicated macro HPAGE_CACHE_INDEX_MASK a533a21b692f mm/shmem: fix shmem_swapin() race with swapoff c3b39134bbd0 swap: fix do_swap_page() race with swapoff Do you suggest reverting "mm/shmem: fix shmem_swapin() race with swapoff" a= s=20 well? =2D-=20 Oleksandr Natalenko (post-factum)