From patchwork Sun Jan 21 19:08:58 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Zygo Blaxell X-Patchwork-Id: 10177055 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 726E8604D4 for ; Sun, 21 Jan 2018 19:14:40 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 56E332022C for ; Sun, 21 Jan 2018 19:14:40 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 495BD26E55; Sun, 21 Jan 2018 19:14:40 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=2.0 tests=BAYES_00,RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 92EBB2022C for ; Sun, 21 Jan 2018 19:14:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750919AbeAUTOT (ORCPT ); Sun, 21 Jan 2018 14:14:19 -0500 Received: from james.kirk.hungrycats.org ([174.142.39.145]:47206 "EHLO james.kirk.hungrycats.org" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1750853AbeAUTOS (ORCPT ); Sun, 21 Jan 2018 14:14:18 -0500 X-Greylist: delayed 317 seconds by postgrey-1.27 at vger.kernel.org; Sun, 21 Jan 2018 14:14:17 EST Received: by james.kirk.hungrycats.org (Postfix, from userid 1002) id 5034C9B7A80; Sun, 21 Jan 2018 14:08:58 -0500 (EST) Date: Sun, 21 Jan 2018 14:08:58 -0500 From: Zygo Blaxell To: linux-btrfs@vger.kernel.org Subject: [PATCH] btrfs: remove spurious WARN_ON(ref->count) in find_parent_nodes Message-ID: <20180121190848.7wmps6q5ng6b42ki@hungrycats.org> MIME-Version: 1.0 Content-Disposition: inline User-Agent: NeoMutt/20170113 (1.7.2) Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP This warning appears during execution of the LOGICAL_INO ioctl and appears to be spurious: ------------[ cut here ]------------ WARNING: CPU: 3 PID: 18172 at fs/btrfs/backref.c:1391 find_parent_nodes+0xc41/0x14e0 Modules linked in: ib_iser rdma_cm iw_cm ib_cm ib_core configfs iscsi_tcp libiscsi_tcp libiscsi scsi_transport_iscsi overlay r8169 ufs qnx4 hfsplus hfs minix ntfs vfat msdos fat jfs xfs cpuid rpcsec_gss_krb5 nfsv4 nfsv3 nfs fscache algif_skcipher af_alg softdog nfsd auth_rpcgss nfs_acl lockd grace sunrpc bnep cpufreq_userspace cpufreq_powersave cpufreq_conservative nfnetlink_queue nfnetlink_log nfnetlink bluetooth rfkill snd_seq_dummy snd_hrtimer snd_seq_midi snd_seq_oss snd_seq_midi_event snd_rawmidi snd_seq snd_seq_device binfmt_misc fuse nbd xt_REDIRECT nf_nat_redirect ipt_REJECT nf_reject_ipv4 xt_nat xt_conntrack xt_tcpudp nf_log_ipv4 nf_log_common xt_LOG ip6table_nat nf_conntrack_ipv6 nf_defrag_ipv6 nf_nat_ipv6 iptable_nat nf_conntrack_ipv4 nf_defrag_ipv4 nf_nat_ipv4 nf_nat nf_conntrack ip6table_mangle iptable_mangle ip6table_filter ip6_tables iptable_filter ip_tables x_tables tcp_cubic dummy lp dm_crypt edac_mce_amd edac_core snd_hda_codec_hdmi ppdev kvm_amd kvm irqbypass crct10dif_pclmul crc32_pclmul ghash_clmulni_intel snd_hda_codec_via pcbc amdkfd snd_hda_codec_generic amd_iommu_v2 aesni_intel snd_hda_intel radeon snd_hda_codec aes_x86_64 snd_hda_core snd_hwdep crypto_simd glue_helper sg snd_pcm_oss cryptd input_leds joydev pcspkr serio_raw snd_mixer_oss rtc_cmos snd_pcm parport_pc parport shpchp wmi acpi_cpufreq evdev snd_timer asus_atk0110 k10temp fam15h_power snd soundcore sp5100_tco hid_generic ipv6 af_packet crc_ccitt raid10 raid456 async_raid6_recov async_memcpy async_pq async_xor async_tx libcrc32c raid0 multipath linear dm_mod raid1 md_mod ohci_pci ide_pci_generic sr_mod cdrom pdc202xx_new ohci_hcd crc32c_intel atiixp ehci_pci psmouse ide_core i2c_piix4 ehci_hcd xhci_pci mii xhci_hcd [last unloaded: r8169] CPU: 3 PID: 18172 Comm: bees Tainted: G D W L 4.11.9-zb64+ #1 Hardware name: System manufacturer System Product Name/M5A78L-M/USB3, BIOS 2101 12/02/2014 Call Trace: dump_stack+0x85/0xc2 __warn+0xd1/0xf0 warn_slowpath_null+0x1d/0x20 find_parent_nodes+0xc41/0x14e0 __btrfs_find_all_roots+0xad/0x120 ? extent_same_check_offsets+0x70/0x70 iterate_extent_inodes+0x168/0x300 iterate_inodes_from_logical+0x87/0xb0 ? iterate_inodes_from_logical+0x87/0xb0 ? extent_same_check_offsets+0x70/0x70 btrfs_ioctl+0x8ac/0x2820 ? lock_acquire+0xc2/0x200 do_vfs_ioctl+0x91/0x700 ? __fget+0x112/0x200 SyS_ioctl+0x79/0x90 entry_SYSCALL_64_fastpath+0x23/0xc6 RIP: 0033:0x7f727b20be07 RSP: 002b:00007f7279f1e018 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: ffffffff9c0f4d7f RCX: 00007f727b20be07 RDX: 00007f7279f1e118 RSI: 00000000c0389424 RDI: 0000000000000003 RBP: 0000000000000035 R08: 00007f72581bf340 R09: 0000000000000000 R10: 0000000000000020 R11: 0000000000000246 R12: 0000000000000040 R13: 00007f725818d230 R14: 00007f7279f1b640 R15: 00007f7258000020 ? trace_hardirqs_off_caller+0x1f/0x140 ---[ end trace 5de243350f6762c6 ]--- ------------[ cut here ]------------ ref->count can be below zero under normal conditions (for delayed refs), so there is no need to spam dmesg when it happens. On kernel v4.14 this warning occurs 100-1000 times more frequently than on kernels v4.2..v4.12. In the worst case, one test machine had 59020 warnings in 24 hours on v4.14.14 compared to 55 on v4.12.14. Signed-off-by: Zygo Blaxell Reviewed-by: Edmund Nadolski --- fs/btrfs/backref.c | 1 - 1 file changed, 1 deletion(-) diff --git a/fs/btrfs/backref.c b/fs/btrfs/backref.c index 7d0dc100a09a..57e8d2562ed5 100644 --- a/fs/btrfs/backref.c +++ b/fs/btrfs/backref.c @@ -1263,7 +1263,6 @@ static int find_parent_nodes(struct btrfs_trans_handle *trans, while (node) { ref = rb_entry(node, struct prelim_ref, rbnode); node = rb_next(&ref->rbnode); - WARN_ON(ref->count < 0); if (roots && ref->count && ref->root_id && ref->parent == 0) { if (sc && sc->root_objectid && ref->root_id != sc->root_objectid) {