From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 899DD2DAFB1 for ; Fri, 17 Oct 2025 09:47:46 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1760694466; cv=none; b=AkaL1IELg0ZZIoXEFToS3cx11YgshriXRgIl5F3COBoWroxtcH0sHcjXlaIFWXShgkSS5ijSNTAEtfOusuGbT452uaKMvPTlBegyoMQnIBzz+TvvS30uHqb+iDD+ymJoLovjWt0ExydnWhC6UJ6rfORBJSH1I+La+raztp18eXs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1760694466; c=relaxed/simple; bh=TgohWvrr8PPcueUdJIB8RPjo736OQrsal4Ke867tpaE=; h=Message-ID:Date:MIME-Version:Cc:Subject:To:References:From: In-Reply-To:Content-Type; b=UAjeRVhhxljTMQXv4FqZuywL4nw8dErjQWsYqddzIrnVsxCtujIBYX5yNv69bJKVWtS+8396dsMG+Q3Iph0ky4m5bWFGKomK2NhO1VquNiJZB6Cd9yFvz4116S6pVbcUtNROOgOIGFFO9mCJEHnXIkaGFMymmCkmHaR7FY9ZeUE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=CgzB5jNG; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="CgzB5jNG" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 00624C4CEE7; Fri, 17 Oct 2025 09:47:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1760694466; bh=TgohWvrr8PPcueUdJIB8RPjo736OQrsal4Ke867tpaE=; h=Date:Cc:Subject:To:References:From:In-Reply-To:From; b=CgzB5jNGATGcNf741gRjhmva5S4P6nntGbmy77yPZX+dr3vBP0NmnuNMcYfVEdZXH Qiowd0Y+zH2AWsFNci2ZtP72GBz7qIuaJVw+V0ITGWcCkDtTX56mWwgtIrwcsVNTy/ AsruebVqs8yGKtGZAqNBMdN/6C8UKzPZEd/jizJScSLNJjD+S8BWnIGIejpxYFP4ti ugrK1qX0Yk9sDAePMUd8XzcnyPJSRBRuYDrKaMVw/6dul0LqhuYlwm19vehovyrY1k eNqSStlm+lDqhQSIzRQ1lGS36FBPzZm8G41e8Cxs5Z2f5VA80aWYsJdTOXV2GxU3q4 GRq9SyzjQc/RA== Message-ID: Date: Fri, 17 Oct 2025 17:47:43 +0800 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Cc: chao@kernel.org, linux-kernel@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net Subject: Re: [f2fs-dev] [PATCH] f2fs: ensure node page reads complete before f2fs_put_super() finishes To: Jaegeuk Kim , Jan Prusakowski References: <20251006084615.2585252-1-jprusakowski@google.com> Content-Language: en-US From: Chao Yu In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 10/17/2025 1:47 AM, Jaegeuk Kim wrote: > On 10/11, Chao Yu wrote: >> On 10/11/25 00:02, Jaegeuk Kim wrote: >>> On 10/09, Chao Yu wrote: >>>> On 10/6/2025 4:46 PM, Jan Prusakowski via Linux-f2fs-devel wrote: >>>>> Xfstests generic/335, generic/336 sometimes crash with the following message: >>>>> >>>>> F2FS-fs (dm-0): detect filesystem reference count leak during umount, type: 9, count: 1 >>>>> ------------[ cut here ]------------ >>>>> kernel BUG at fs/f2fs/super.c:1939! >>>>> Oops: invalid opcode: 0000 [#1] SMP NOPTI >>>>> CPU: 1 UID: 0 PID: 609351 Comm: umount Tainted: G W 6.17.0-rc5-xfstests-g9dd1835ecda5 #1 PREEMPT(none) >>>>> Tainted: [W]=WARN >>>>> Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 >>>>> RIP: 0010:f2fs_put_super+0x3b3/0x3c0 >>>>> Call Trace: >>>>> >>>>> generic_shutdown_super+0x7e/0x190 >>>>> kill_block_super+0x1a/0x40 >>>>> kill_f2fs_super+0x9d/0x190 >>>>> deactivate_locked_super+0x30/0xb0 >>>>> cleanup_mnt+0xba/0x150 >>>>> task_work_run+0x5c/0xa0 >>>>> exit_to_user_mode_loop+0xb7/0xc0 >>>>> do_syscall_64+0x1ae/0x1c0 >>>>> entry_SYSCALL_64_after_hwframe+0x76/0x7e >>>>> >>>>> ---[ end trace 0000000000000000 ]--- >>>>> >>>>> It appears that sometimes it is possible that f2fs_put_super() is called before >>>>> all node page reads are completed. >>>>> Adding a call to f2fs_wait_on_all_pages() for F2FS_RD_NODE fixes the problem. >>>>> >>>>> Fixes: bf22c3cc8ce7 ("f2fs: fix the panic in do_checkpoint()") >>>>> >>>>> Signed-off-by: Jan Prusakowski >>>>> --- >>>>> fs/f2fs/super.c | 1 + >>>>> 1 file changed, 1 insertion(+) >>>>> >>>>> diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c >>>>> index 1e0678e37a30..5c94bc42b8a1 100644 >>>>> --- a/fs/f2fs/super.c >>>>> +++ b/fs/f2fs/super.c >>>>> @@ -1976,6 +1976,7 @@ static void f2fs_put_super(struct super_block *sb) >>>>> f2fs_flush_merged_writes(sbi); >>>>> f2fs_wait_on_all_pages(sbi, F2FS_WB_CP_DATA); >>>>> + f2fs_wait_on_all_pages(sbi, F2FS_RD_NODE); >>>> >>>> Jan, >>>> >>>> At this stage, GC and checkpoint are both stopped, why there is still read >>>> IOs on node page? Who is reading node page? Can you please dig more details >>>> for this issue? >>> >>> We don't actually wait for completing read IOs. So, I think it doesn't matter >>> the threads are stopped? >> >> Read on node page should be synchronous? so if the threads are stopped, there >> should be no node IOs? Oh, Or there is still pending asynchronous readahead IO >> on node page after all threads are stopped? > > I remember we submit IOs and wait for its completion when we need by lock_page. We also support readahead on page from meta_inode and common inode, so how about waiting for all potential inflight read IOs? In addtion, f2fs_wait_on_all_pages() is used for write path, how about simplifying as below? diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c index 4c7da160ca27..ea731f8bf19c 100644 --- a/fs/f2fs/super.c +++ b/fs/f2fs/super.c @@ -1983,6 +1983,12 @@ static void f2fs_put_super(struct super_block *sb) f2fs_wait_on_all_pages(sbi, F2FS_WB_CP_DATA); + /* wait for potential inflight readahead IOs */ + for (i = F2FS_RD_DATA; i <= F2FS_RD_META; i++) { + while (get_pages(sbi, i)) + io_schedule_timeout(DEFAULT_IO_TIMEOUT); + } + if (err || f2fs_cp_error(sbi)) { truncate_inode_pages_final(NODE_MAPPING(sbi)); truncate_inode_pages_final(META_MAPPING(sbi)); -- 2.40.1 Thanks, > >> >> Thanks, >> >>> >>>> >>>> Thanks, >>>> >>>>> if (err || f2fs_cp_error(sbi)) { >>>>> truncate_inode_pages_final(NODE_MAPPING(sbi));