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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B72FCC433EF for ; Thu, 21 Oct 2021 12:11:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9701B61221 for ; Thu, 21 Oct 2021 12:11:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231156AbhJUMNl (ORCPT ); Thu, 21 Oct 2021 08:13:41 -0400 Received: from mail.kernel.org ([198.145.29.99]:56122 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229765AbhJUMNj (ORCPT ); Thu, 21 Oct 2021 08:13:39 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id BA95D6120C; Thu, 21 Oct 2021 12:11:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1634818284; bh=l6RlEt0NEP+wUUaiwunsNXw+CERWuWBXIp8i5TT1qUs=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=heKUUSPIqGR8MdLQKSk32+oNXXHyTM5L0UO/E4WKrptRN3zaROJS5aY1SDlt7V14h HNH1+t4Hv9S8Nof+xJtQUmhKICWZ2yANGNI6CDI86RxrxnZMmNCnLWN3mLMMPphXsX 916vECaeqmliZjpbu05MOq4xAZMtsSmmGL1Li6c7LaxOHA+zW9RLpSCvDRsL51fzYw BvAOELBGozQND8uxb2IhG18Fc6JjYuhMD4beAr0rrpPGzSYkiiq9uxlqinG5HWnaSK KMwTUPcEcdQpQG5dVZ2LsQgZ9MtTR9xD5K+OxYDtP8gpYcKZ6Hh3+GsqbOumSLRoLs JdDI5Ar3sggHg== Message-ID: Date: Thu, 21 Oct 2021 20:11:20 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:91.0) Gecko/20100101 Thunderbird/91.2.0 Subject: Re: [f2fs-dev] [PATCH] f2fs: remove circular locking between sb_internal and fs_reclaim Content-Language: en-US To: Daeho Jeong , linux-kernel@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, kernel-team@android.com Cc: Daeho Jeong References: <20211014190503.717830-1-daeho43@gmail.com> From: Chao Yu In-Reply-To: <20211014190503.717830-1-daeho43@gmail.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2021/10/15 3:05, Daeho Jeong wrote: > From: Daeho Jeong > > We detected the below circular locking dependency between sb_internal > and fs_reclaim. So, removed it by calling dquot_initialize() before > sb_start_intwrite(). > > ====================================================== > WARNING: possible circular locking dependency detected > ------------------------------------------------------ > kswapd0/133 is trying to acquire lock: > ffffff80d5fb9680 (sb_internal#2){.+.+}-{0:0}, at: evict+0xd4/0x2f8 > > but task is already holding lock: > ffffffda597c93a8 (fs_reclaim){+.+.}-{0:0}, at: > __fs_reclaim_acquire+0x4/0x50 > > which lock already depends on the new lock. > ... > other info that might help us debug this: > > Chain exists of: > > sb_internal#2 --> &s->s_dquot.dqio_sem --> fs_reclaim > > Possible unsafe locking scenario: > > CPU0 CPU1 > ---- ---- > lock(fs_reclaim); > lock(&s->s_dquot.dqio_sem); > lock(fs_reclaim); > lock(sb_internal#2); Sorry, I still didn't get the root cause of this deadlock issue, could you please explain more about this? And why calling dquot_initialize() in drop_inode() could break the circular locking dependency? Thanks, > > Signed-off-by: Daeho Jeong > --- > fs/f2fs/super.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c > index 86eeb019cc52..a133932333c5 100644 > --- a/fs/f2fs/super.c > +++ b/fs/f2fs/super.c > @@ -1370,6 +1370,8 @@ static int f2fs_drop_inode(struct inode *inode) > /* should remain fi->extent_tree for writepage */ > f2fs_destroy_extent_node(inode); > > + dquot_initialize(inode); > + > sb_start_intwrite(inode->i_sb); > f2fs_i_size_write(inode, 0); > >