Hi all,
I'm running Fedora 25 with kernel 4.8.15 (also tested 4.8.14), and when I go to mount my USB BTRFS filesystem, the PC freezes completely.
I have managed to get a kernel crash once out of the number of freezes - and I have attached that log. I have also posted a copy here: https://paste.fedoraproject.org/520173/36148521/raw/
I don't believe there is anything physically wrong with the USB drive, as I can read at least the first 120Gb with dd via: dd if=/dev/sdc1 of=/dev/null bs=1M
I can successfully run btrfsck - and no read errors or messages are logged: $ btrfsck /dev/sdc1 Checking filesystem on /dev/sdc1 UUID: dba49c2d-5362-47ae-b25a-3c3e3aa1b66f checking extents checking free space cache checking fs roots checking csums checking root refs found 161932349440 bytes used err is 0 total csum bytes: 156784812 total tree bytes: 1338654720 total fs tree bytes: 1091043328 total extent tree bytes: 76120064 btree space waste bytes: 219938988 file data blocks allocated: 160593731584 referenced 160593694720
Even though the tool mentions the 'repair is considered dangerous', I ran it anyway, and got the following: $ btrfsck --repair -p /dev/sdc1 enabling repair mode Checking filesystem on /dev/sdc1 UUID: dba49c2d-5362-47ae-b25a-3c3e3aa1b66f checking extents [O] Fixed 0 roots. cache and super generation don't match, space cache will be invalidated checking fs roots [.] checking csums checking root refs found 161932349440 bytes used err is 0 total csum bytes: 156784812 total tree bytes: 1338654720 total fs tree bytes: 1091043328 total extent tree bytes: 76120064 btree space waste bytes: 219938988 file data blocks allocated: 160593731584 referenced 160593694720
I tried to mount the filesystem again - and while the system doesn't hard freeze, I get the following crash: kernel: BTRFS info (device sdc1): disk space caching is enabled kernel: BTRFS info (device sdc1): has skinny extents kernel: BUG: unable to handle kernel NULL pointer dereference at 000000000000035c kernel: IP: [<ffffffffc14eec0d>] flush_space+0x2ed/0x620 [btrfs] kernel: PGD 0 kernel: Oops: 0000 [#1] SMP kernel: Modules linked in: btrfs xor raid6_pq uas usb_storage rfcomm ip6t_rpfilter ip6t_REJECT nf_reject_ipv6 xt_conntrack ip_set nfnetlink ebtable_nat ebtable_broute bridge stp llc ip6table_raw ip6table_security ip6table_nat nf_conntrack_ipv6 nf_defrag_ipv6 nf_nat_ipv6 ip6table_mangle iptable_raw iptable_security iptable_nat nf_conntrack_ipv4 nf_defrag_ipv4 nf_nat_ipv4 nf_nat nf_conntrack iptable_mangle ebtable_filter ebtables ip6table_filter ip6_tables bnep hwmon_vid snd_hda_codec_hdmi intel_powerclamp coretemp kvm_intel kvm irqbypass nvidia_drm(POE) ir_lirc_codec intel_cstate nvidia_modeset(POE) lirc_dev intel_uncore iTCO_wdt nvidia(POE) iTCO_vendor_support snd_hda_codec_realtek r820t snd_hda_codec_generic rtl2832 i2c_mux snd_hda_intel snd_hda_codec snd_hda_core snd_hwdep snd_seq btusb btrtl kernel: snd_seq_device btbcm btintel snd_pcm bluetooth dvb_usb_rtl28xxu r8169 dvb_usb_v2 joydev drm_kms_helper dvb_core i2c_i801 rc_core rfkill drm i2c_smbus snd_timer mii lpc_ich snd soundcore i7core_edac i5500_temp edac_core acpi_cpufreq tpm_tis tpm_tis_core asus_atk0110 shpchp tpm nfsd auth_rpcgss nfs_acl lockd grace sunrpc xfs libcrc32c mxm_wmi crc32c_intel serio_raw hid_microsoft fjes wmi kernel: CPU: 6 PID: 2910 Comm: mount Tainted: P IOE 4.8.15-300.fc25.x86_64 #1 kernel: Hardware name: System manufacturer System Product Name/P6X58D-E, BIOS 0803 08/06/2012 kernel: task: ffffa2456d639d40 task.stack: ffffa245afd28000 kernel: RIP: 0010:[<ffffffffc14eec0d>] [<ffffffffc14eec0d>] flush_space+0x2ed/0x620 [btrfs] kernel: RSP: 0018:ffffa245afd2b760 EFLAGS: 00010246 kernel: RAX: 0000000000000001 RBX: 00000000ffffffff RCX: 0000000000020000 kernel: RDX: 0000000000020000 RSI: ffffa24584e9f800 RDI: 0000000000000000 kernel: RBP: ffffa245afd2b818 R08: 0000000000000001 R09: 0000000000000000 kernel: R10: 00000000ffffffe4 R11: 0000000000000100 R12: 0000000000000000 kernel: R13: 0000000000020000 R14: 0000000000000001 R15: 0000000000000002 kernel: FS: 00007f1f55eaf340(0000) GS:ffffa245f9380000(0000) knlGS:0000000000000000 kernel: CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 kernel: CR2: 000000000000035c CR3: 0000000124578000 CR4: 00000000000006e0 kernel: Stack: kernel: ffffa24561c09cc0 0000000000000000 0000000000000000 ffffa24561c09b40 kernel: ffffa24584e9f800 00000000e2c595b9 ffffa245afd2b7f8 ffffa24561c09cb8 kernel: 0007ffffffffffff ffffa245afd2b7d0 0000000000020000 0000000000020000 kernel: Call Trace: kernel: [<ffffffffc14e1e3a>] ? can_overcommit.part.70+0x6a/0x100 [btrfs] kernel: [<ffffffffc14ef5c4>] reserve_metadata_bytes+0x1c4/0xb60 [btrfs] kernel: [<ffffffffc14f0825>] btrfs_block_rsv_refill+0x75/0xa0 [btrfs] kernel: [<ffffffffc15113b8>] btrfs_evict_inode+0x3e8/0x5c0 [btrfs] kernel: [<ffffffffb30e4e10>] ? wake_atomic_t_function+0x60/0x60 kernel: [<ffffffffb326d4f3>] evict+0xb3/0x180 kernel: [<ffffffffb326d7d0>] iput+0x1b0/0x230 kernel: [<ffffffffc1512032>] btrfs_orphan_cleanup+0x1f2/0x430 [btrfs] kernel: [<ffffffffc155f761>] btrfs_recover_relocation+0x351/0x460 [btrfs] kernel: [<ffffffffc14fcd9c>] ? btrfs_cleanup_fs_roots+0x14c/0x180 [btrfs] kernel: [<ffffffffc1501065>] open_ctree+0x2045/0x2520 [btrfs] kernel: [<ffffffffc14d44b2>] btrfs_mount+0xda2/0xef0 [btrfs] kernel: [<ffffffffb33fbb9d>] ? find_next_zero_bit+0x1d/0x20 kernel: [<ffffffffb33fbb78>] ? find_next_bit+0x18/0x20 kernel: [<ffffffffb3254bb8>] mount_fs+0x38/0x150 kernel: [<ffffffffb31e39a5>] ? __alloc_percpu+0x15/0x20 kernel: [<ffffffffb3271d97>] vfs_kern_mount+0x67/0x100 kernel: [<ffffffffc14d38b3>] btrfs_mount+0x1a3/0xef0 [btrfs] kernel: [<ffffffffb33fbb9d>] ? find_next_zero_bit+0x1d/0x20 kernel: [<ffffffffb3254bb8>] mount_fs+0x38/0x150 kernel: [<ffffffffb31e39a5>] ? __alloc_percpu+0x15/0x20 kernel: [<ffffffffb3271d97>] vfs_kern_mount+0x67/0x100 kernel: [<ffffffffb327424d>] do_mount+0x1dd/0xc50 kernel: [<ffffffffb324c0b5>] ? __check_object_size+0x105/0x1dc kernel: [<ffffffffb31ddccf>] ? memdup_user+0x4f/0x70 kernel: [<ffffffffb3274fc3>] SyS_mount+0x83/0xd0 kernel: [<ffffffffb3803b72>] entry_SYSCALL_64_fastpath+0x1a/0xa4 kernel: Code: 48 8b 4d 98 4c 89 e2 4c 89 ee ff d0 49 8b 06 48 85 c0 75 da e9 78 ff ff ff 48 98 48 c1 e0 12 48 89 85 78 ff ff ff e9 d6 fe ff ff <8b> 8f 5c 03 00 00 48 8b 45 98 31 d2 c1 e1 04 48 f7 f1 8d 1c 00 kernel: RIP [<ffffffffc14eec0d>] flush_space+0x2ed/0x620 [btrfs] kernel: RSP <ffffa245afd2b760> kernel: CR2: 000000000000035c kernel: ---[ end trace c49186b736aa143c ]---
Has anyone seen this recently or have any ideas on how to fix this problem?
I originally posted this to the linux-btrfs mailing list, and the #btrfs irc channel on freenode - but have had zero response from anyone :(