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=-17.5 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=ham 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 0441AC07E95 for ; Mon, 19 Jul 2021 18:10:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D88EB610F7 for ; Mon, 19 Jul 2021 18:10:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1351633AbhGSR36 (ORCPT ); Mon, 19 Jul 2021 13:29:58 -0400 Received: from mail.kernel.org ([198.145.29.99]:35770 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1355710AbhGSRYD (ORCPT ); Mon, 19 Jul 2021 13:24:03 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id BCE0961006; Mon, 19 Jul 2021 18:04:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1626717881; bh=9as0j8CiNrSuZT5+O13jymSlEI71fFFkRK1kxuK+uek=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=f/UsVwE34gSFoCxfJ/G/w43xOp9PTXdJ4bVR8czoXEqwyc/fJQVp0l7RXRC6adZDk dncCqnR4Z9tJEX7BRpJMrlXSFsvKAqrUoaPK6okOAZneoyMY+zfOOFYC9WnmeK39Y0 QcD48rA6DgD2mTHM9FwqfxTynEl5FeF4cmzKd3J7aOp200pGFijNEjAftYAVwCtHmW LY06mmUeCG9i0UD/gN848Lrw+3p/3RTeRQ7JydB1eCaNPa5UwDj6P6ag5mT8wOCdaH 7wOUXlGnwsvuPcqBwA8ZiPaQwTOlnDch6FVj3HphY/Gsw7uaCaTA6sJ9fe7Iz4fdWq ttj1aB01S84Lw== Date: Mon, 19 Jul 2021 11:04:41 -0700 From: "Darrick J. Wong" To: Roman Gushchin Cc: Andrew Morton , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, Jan Kara , Dave Chinner , Murphy Zhou , Matthew Wilcox Subject: Re: [PATCH] writeback, cgroup: do not reparent dax inodes Message-ID: <20210719180441.GH23236@magnolia> References: <20210719171350.3876830-1-guro@fb.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210719171350.3876830-1-guro@fb.com> Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Mon, Jul 19, 2021 at 10:13:50AM -0700, Roman Gushchin wrote: > The inode switching code is not suited for dax inodes. An attempt > to switch a dax inode to a parent writeback structure (as a part > of a writeback cleanup procedure) results in a panic like this: > > [ 987.071651] run fstests generic/270 at 2021-07-15 05:54:02 > [ 988.704940] XFS (pmem0p2): EXPERIMENTAL big timestamp feature in > use. Use at your own risk! > [ 988.746847] XFS (pmem0p2): DAX enabled. Warning: EXPERIMENTAL, use > at your own risk > [ 988.786070] XFS (pmem0p2): EXPERIMENTAL inode btree counters > feature in use. Use at your own risk! > [ 988.828639] XFS (pmem0p2): Mounting V5 Filesystem > [ 988.854019] XFS (pmem0p2): Ending clean mount > [ 988.874550] XFS (pmem0p2): Quotacheck needed: Please wait. > [ 988.900618] XFS (pmem0p2): Quotacheck: Done. > [ 989.090783] XFS (pmem0p2): xlog_verify_grant_tail: space > BBTOB(tail_blocks) > [ 989.092751] XFS (pmem0p2): xlog_verify_grant_tail: space > BBTOB(tail_blocks) > [ 989.092962] XFS (pmem0p2): xlog_verify_grant_tail: space > BBTOB(tail_blocks) > [ 1010.105586] BUG: unable to handle page fault for address: 0000000005b0f669 > [ 1010.141817] #PF: supervisor read access in kernel mode > [ 1010.167824] #PF: error_code(0x0000) - not-present page > [ 1010.191499] PGD 0 P4D 0 > [ 1010.203346] Oops: 0000 [#1] SMP PTI > [ 1010.219596] CPU: 13 PID: 10479 Comm: kworker/13:16 Not tainted > 5.14.0-rc1-master-8096acd7442e+ #8 > [ 1010.260441] Hardware name: HP ProLiant DL360 Gen9/ProLiant DL360 > Gen9, BIOS P89 09/13/2016 > [ 1010.297792] Workqueue: inode_switch_wbs inode_switch_wbs_work_fn > [ 1010.324832] RIP: 0010:inode_do_switch_wbs+0xaf/0x470 > [ 1010.347261] Code: 00 30 0f 85 c1 03 00 00 0f 1f 44 00 00 31 d2 48 > c7 c6 ff ff ff ff 48 8d 7c 24 08 e8 eb 49 1a 00 48 85 c0 74 4a bb ff > ff ff ff <48> 8b 50 08 48 8d 4a ff 83 e2 01 48 0f 45 c1 48 8b 00 a8 08 > 0f 85 > [ 1010.434307] RSP: 0018:ffff9c66691abdc8 EFLAGS: 00010002 > [ 1010.457795] RAX: 0000000005b0f661 RBX: 00000000ffffffff RCX: ffff89e6a21382b0 > [ 1010.489922] RDX: 0000000000000001 RSI: ffff89e350230248 RDI: ffffffffffffffff > [ 1010.522085] RBP: ffff89e681d19400 R08: 0000000000000000 R09: 0000000000000228 > [ 1010.554234] R10: ffffffffffffffff R11: ffffffffffffffc0 R12: ffff89e6a2138130 > [ 1010.586414] R13: ffff89e316af7400 R14: ffff89e316af6e78 R15: ffff89e6a21382b0 > [ 1010.619394] FS: 0000000000000000(0000) GS:ffff89ee5fb40000(0000) > knlGS:0000000000000000 > [ 1010.658874] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > [ 1010.688085] CR2: 0000000005b0f669 CR3: 0000000cb2410004 CR4: 00000000001706e0 > [ 1010.722129] Call Trace: > [ 1010.733132] inode_switch_wbs_work_fn+0xb6/0x2a0 > [ 1010.754121] process_one_work+0x1e6/0x380 > [ 1010.772512] worker_thread+0x53/0x3d0 > [ 1010.789221] ? process_one_work+0x380/0x380 > [ 1010.807964] kthread+0x10f/0x130 > [ 1010.822043] ? set_kthread_struct+0x40/0x40 > [ 1010.840818] ret_from_fork+0x22/0x30 > [ 1010.856851] Modules linked in: xt_CHECKSUM xt_MASQUERADE > xt_conntrack ipt_REJECT nf_reject_ipv4 nft_compat nft_chain_nat nf_nat > nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 nft_counter nf_tables > nfnetlink bridge stp llc rfkill sunrpc intel_rapl_msr > intel_rapl_common sb_edac x86_pkg_temp_thermal intel_powerclamp > coretemp kvm_intel ipmi_ssif kvm mgag200 i2c_algo_bit iTCO_wdt > irqbypass drm_kms_helper iTCO_vendor_support acpi_ipmi rapl > syscopyarea sysfillrect intel_cstate ipmi_si sysimgblt ioatdma > dax_pmem_compat fb_sys_fops ipmi_devintf device_dax i2c_i801 pcspkr > intel_uncore hpilo nd_pmem cec dax_pmem_core dca i2c_smbus acpi_tad > lpc_ich ipmi_msghandler acpi_power_meter drm fuse xfs libcrc32c sd_mod > t10_pi crct10dif_pclmul crc32_pclmul crc32c_intel tg3 > ghash_clmulni_intel serio_raw hpsa hpwdt scsi_transport_sas wmi > dm_mirror dm_region_hash dm_log dm_mod > [ 1011.200864] CR2: 0000000005b0f669 > [ 1011.215700] ---[ end trace ed2105faff8384f3 ]--- > [ 1011.241727] RIP: 0010:inode_do_switch_wbs+0xaf/0x470 > [ 1011.264306] Code: 00 30 0f 85 c1 03 00 00 0f 1f 44 00 00 31 d2 48 > c7 c6 ff ff ff ff 48 8d 7c 24 08 e8 eb 49 1a 00 48 85 c0 74 4a bb ff > ff ff ff <48> 8b 50 08 48 8d 4a ff 83 e2 01 48 0f 45 c1 48 8b 00 a8 08 > 0f 85 > [ 1011.348821] RSP: 0018:ffff9c66691abdc8 EFLAGS: 00010002 > [ 1011.372734] RAX: 0000000005b0f661 RBX: 00000000ffffffff RCX: ffff89e6a21382b0 > [ 1011.405826] RDX: 0000000000000001 RSI: ffff89e350230248 RDI: ffffffffffffffff > [ 1011.437852] RBP: ffff89e681d19400 R08: 0000000000000000 R09: 0000000000000228 > [ 1011.469926] R10: ffffffffffffffff R11: ffffffffffffffc0 R12: ffff89e6a2138130 > [ 1011.502179] R13: ffff89e316af7400 R14: ffff89e316af6e78 R15: ffff89e6a21382b0 > [ 1011.534233] FS: 0000000000000000(0000) GS:ffff89ee5fb40000(0000) > knlGS:0000000000000000 > [ 1011.571247] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > [ 1011.597063] CR2: 0000000005b0f669 CR3: 0000000cb2410004 CR4: 00000000001706e0 > [ 1011.629160] Kernel panic - not syncing: Fatal exception > [ 1011.653802] Kernel Offset: 0x15200000 from 0xffffffff81000000 > (relocation range: 0xffffffff80000000-0xffffffffbfffffff) > [ 1011.713723] ---[ end Kernel panic - not syncing: Fatal exception ]--- > > The crash happens on an attempt to iterate over attached pagecache > pages and check the dirty flag: a dax inode's xarray contains pfn's > instead of generic struct page pointers. > > Fix the problem by bailing out (with the false return value) of > inode_prepare_sbs_switch() if a dax inode is passed. > > Fixes: c22d70a162d3 ("writeback, cgroup: release dying cgwbs by switching attached inodes") > Signed-off-by: Roman Gushchin > Reported-by: Murphy Zhou > Reported-by: Darrick J. Wong > Tested-by: Murphy Zhou > Cc: Matthew Wilcox Seems to fix the problem here too, so: Tested-by: Darrick J. Wong --D > --- > fs/fs-writeback.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c > index 06d04a74ab6c..4c3370548982 100644 > --- a/fs/fs-writeback.c > +++ b/fs/fs-writeback.c > @@ -521,6 +521,9 @@ static bool inode_prepare_wbs_switch(struct inode *inode, > */ > smp_mb(); > > + if (IS_DAX(inode)) > + return false; > + > /* while holding I_WB_SWITCH, no one else can update the association */ > spin_lock(&inode->i_lock); > if (!(inode->i_sb->s_flags & SB_ACTIVE) || > -- > 2.31.1 >