kernel BUG at /build/linux-H5UzH8/linux-4.10.0/fs/btrfs/extent_io.c:2318

kernel BUG at /build/linux-H5UzH8/linux-4.10.0/fs/btrfs/extent_io.c:2318

[Piotr Pawłow]

Hello,

my btrfs raid1 fs with 4 drives crashed after only one drive developed a
couple of bad blocks.

Seems similar to https://bugzilla.kernel.org/show_bug.cgi?id=196251 but
it happened during normal usage instead of during replace.

As a sidenote, I tried to make the system less noisy during the day,
when it's not doing nightly backups, by setting drives to spin down
after a few minutes. Unfortunately btrfs kept them spinning for no
reason, so I tried systemd's automount to unmount the fs when not in
use. It worked, but it seems it uncovered some kind of umount/mount race
condition, where mount unexpectedly failed with:

sie 06 03:47:39 pps kernel: BTRFS error (device dm-1): super_total_bytes 3855366488064 mismatch with fs_devices total_rw_bytes 7710732976128
sie 06 03:47:39 pps kernel: BTRFS error (device dm-1): failed to read chunk tree: -22
sie 06 03:47:39 pps kernel: BTRFS error (device dm-1): open_ctree failed

...and then the next mount worked properly as if nothing had happened.

Full log: https://pp.siedziba.pl/btrfs_raid1_fail/kernel.log

# uname -a
Linux pps 4.10.0-30-generic #34-Ubuntu SMP Mon Jul 31 19:38:17 UTC 2017 x86_64 x86_64 x86_64 GNU/Linux

# btrfs device usage /backup
/dev/mapper/pps-backup1, ID: 2
   Device size:           465.76GiB
   Device slack:              0.00B
   Data,RAID1:            387.00GiB
   Metadata,RAID1:         16.00GiB
   Unallocated:            62.76GiB

/dev/mapper/pps-backup2, ID: 8
   Device size:             1.81TiB
   Device slack:              0.00B
   Data,RAID1:              1.48TiB
   Metadata,RAID1:         26.00GiB
   System,RAID1:           32.00MiB
   Unallocated:           314.29GiB

/dev/mapper/pps-backup3, ID: 6
   Device size:           334.69GiB
   Device slack:              0.00B
   Data,RAID1:            268.00GiB
   Metadata,RAID1:          5.00GiB
   System,RAID1:           32.00MiB
   Unallocated:            61.66GiB

/dev/mapper/pps-backup4, ID: 7
   Device size:           931.51GiB
   Device slack:              0.00B
   Data,RAID1:            863.00GiB
   Metadata,RAID1:          5.00GiB
   System,RAID1:           64.00MiB
   Unallocated:            63.45GiB

# btrfs device stats /backup
[/dev/mapper/pps-backup1].write_io_errs    0
[/dev/mapper/pps-backup1].read_io_errs     0
[/dev/mapper/pps-backup1].flush_io_errs    0
[/dev/mapper/pps-backup1].corruption_errs  0
[/dev/mapper/pps-backup1].generation_errs  0
[/dev/mapper/pps-backup3].write_io_errs    0
[/dev/mapper/pps-backup3].read_io_errs     0
[/dev/mapper/pps-backup3].flush_io_errs    0
[/dev/mapper/pps-backup3].corruption_errs  0
[/dev/mapper/pps-backup3].generation_errs  0
[/dev/mapper/pps-backup4].write_io_errs    0
[/dev/mapper/pps-backup4].read_io_errs     0
[/dev/mapper/pps-backup4].flush_io_errs    0
[/dev/mapper/pps-backup4].corruption_errs  0
[/dev/mapper/pps-backup4].generation_errs  0
[/dev/mapper/pps-backup2].write_io_errs    1
[/dev/mapper/pps-backup2].read_io_errs     22
[/dev/mapper/pps-backup2].flush_io_errs    0
[/dev/mapper/pps-backup2].corruption_errs  0
[/dev/mapper/pps-backup2].generation_errs  0

sie 07 04:45:05 pps kernel: ------------[ cut here ]------------
sie 07 04:45:05 pps kernel: BTRFS critical (device dm-1): stripe index math went horribly wrong, got stripe_index=2176876031, num_stripes=2
sie 07 04:45:05 pps kernel: BTRFS critical (device dm-1): stripe index math went horribly wrong, got stripe_index=2176876031, num_stripes=2
sie 07 04:45:05 pps kernel: BTRFS critical (device dm-1): stripe index math went horribly wrong, got stripe_index=2176876031, num_stripes=2
sie 07 04:45:05 pps kernel: BTRFS critical (device dm-1): stripe index math went horribly wrong, got stripe_index=2176876031, num_stripes=2
sie 07 04:45:05 pps kernel: BTRFS critical (device dm-1): stripe index math went horribly wrong, got stripe_index=2176876031, num_stripes=2
sie 07 04:45:05 pps kernel: BTRFS critical (device dm-1): stripe index math went horribly wrong, got stripe_index=2176876031, num_stripes=2
sie 07 04:45:05 pps kernel: BTRFS critical (device dm-1): stripe index math went horribly wrong, got stripe_index=2176876031, num_stripes=2
sie 07 04:45:05 pps kernel: BTRFS critical (device dm-1): stripe index math went horribly wrong, got stripe_index=2176876031, num_stripes=2
sie 07 04:45:05 pps kernel: BTRFS critical (device dm-1): stripe index math went horribly wrong, got stripe_index=2176876031, num_stripes=2
sie 07 04:45:05 pps kernel: BTRFS critical (device dm-1): stripe index math went horribly wrong, got stripe_index=2176876031, num_stripes=2
sie 07 04:45:05 pps kernel: BTRFS critical (device dm-1): stripe index math went horribly wrong, got stripe_index=2176876031, num_stripes=2
sie 07 04:45:05 pps kernel: BTRFS critical (device dm-1): stripe index math went horribly wrong, got stripe_index=2176876031, num_stripes=2
sie 07 04:45:05 pps kernel: BTRFS critical (device dm-1): stripe index math went horribly wrong, got stripe_index=2176876031, num_stripes=2
sie 07 04:45:05 pps kernel: BTRFS critical (device dm-1): stripe index math went horribly wrong, got stripe_index=2176876031, num_stripes=2
sie 07 04:45:05 pps kernel: BTRFS critical (device dm-1): stripe index math went horribly wrong, got stripe_index=2176876031, num_stripes=2
sie 07 04:45:05 pps kernel: BTRFS critical (device dm-1): stripe index math went horribly wrong, got stripe_index=2176876031, num_stripes=2
sie 07 04:45:05 pps kernel: BTRFS critical (device dm-1): stripe index math went horribly wrong, got stripe_index=2176876031, num_stripes=2
sie 07 04:45:05 pps kernel: BTRFS critical (device dm-1): stripe index math went horribly wrong, got stripe_index=2176876031, num_stripes=2
sie 07 04:45:05 pps kernel: BTRFS info (device dm-1): csum failed ino 1340360 extent 5370531217408 csum 4180793733 wanted 722897355 mirror -2118091264
sie 07 04:45:05 pps kernel: BTRFS critical (device dm-1): stripe index math went horribly wrong, got stripe_index=2176876031, num_stripes=2
sie 07 04:45:05 pps kernel: BTRFS critical (device dm-1): stripe index math went horribly wrong, got stripe_index=2176876031, num_stripes=2
sie 07 04:45:05 pps kernel: BTRFS info (device dm-1): csum failed ino 1340360 extent 5370531217408 csum 1247241319 wanted 722897355 mirror -2118091264
sie 07 04:45:05 pps kernel: BTRFS critical (device dm-1): stripe index math went horribly wrong, got stripe_index=2176876031, num_stripes=2
sie 07 04:45:05 pps kernel: BTRFS info (device dm-1): csum failed ino 1340360 extent 5370531217408 csum 2555610504 wanted 722897355 mirror -2118091264
sie 07 04:45:05 pps kernel: BTRFS critical (device dm-1): stripe index math went horribly wrong, got stripe_index=2176876031, num_stripes=2
sie 07 04:45:05 pps kernel: BTRFS info (device dm-1): csum failed ino 1340360 extent 5370531217408 csum 2566472073 wanted 722897355 mirror -2118091264
sie 07 04:45:05 pps kernel: BTRFS critical (device dm-1): stripe index math went horribly wrong, got stripe_index=2176876031, num_stripes=2
sie 07 04:45:05 pps kernel: BTRFS info (device dm-1): csum failed ino 1340360 extent 5370531217408 csum 2377887016 wanted 722897355 mirror -2118091264
sie 07 04:45:05 pps kernel: BTRFS critical (device dm-1): stripe index math went horribly wrong, got stripe_index=2176876031, num_stripes=2
sie 07 04:45:05 pps kernel: BTRFS info (device dm-1): csum failed ino 1340360 extent 5370531217408 csum 1742047832 wanted 722897355 mirror -2118091264
sie 07 04:45:05 pps kernel: BTRFS critical (device dm-1): stripe index math went horribly wrong, got stripe_index=2176876031, num_stripes=2
sie 07 04:45:05 pps kernel: BTRFS info (device dm-1): csum failed ino 1340360 extent 5370531217408 csum 3196580372 wanted 722897355 mirror -2118091264
sie 07 04:45:05 pps kernel: BTRFS critical (device dm-1): stripe index math went horribly wrong, got stripe_index=2176876031, num_stripes=2
sie 07 04:45:05 pps kernel: BTRFS info (device dm-1): csum failed ino 1340360 extent 5370531217408 csum 1719006478 wanted 722897355 mirror -2118091264
sie 07 04:45:05 pps kernel: BTRFS info (device dm-1): csum failed ino 1340360 extent 5370531217408 csum 1459008984 wanted 722897355 mirror -2118091264
sie 07 04:45:05 pps kernel: BTRFS critical (device dm-1): stripe index math went horribly wrong, got stripe_index=2176876031, num_stripes=2
sie 07 04:45:05 pps kernel: BTRFS critical (device dm-1): stripe index math went horribly wrong, got stripe_index=2176876031, num_stripes=2
sie 07 04:45:05 pps kernel: BTRFS critical (device dm-1): stripe index math went horribly wrong, got stripe_index=2176876031, num_stripes=2
sie 07 04:45:05 pps kernel: BTRFS critical (device dm-1): stripe index math went horribly wrong, got stripe_index=2176876031, num_stripes=2
sie 07 04:45:05 pps kernel: BTRFS critical (device dm-1): stripe index math went horribly wrong, got stripe_index=2176876031, num_stripes=2
sie 07 04:45:05 pps kernel: BTRFS critical (device dm-1): stripe index math went horribly wrong, got stripe_index=2176876031, num_stripes=2
sie 07 04:45:05 pps kernel: BTRFS critical (device dm-1): stripe index math went horribly wrong, got stripe_index=2176876031, num_stripes=2
sie 07 04:45:05 pps kernel: BTRFS critical (device dm-1): stripe index math went horribly wrong, got stripe_index=2176876031, num_stripes=2
sie 07 04:45:05 pps kernel: BTRFS critical (device dm-1): stripe index math went horribly wrong, got stripe_index=2176876031, num_stripes=2
sie 07 04:45:06 pps kernel: BTRFS critical (device dm-1): stripe index math went horribly wrong, got stripe_index=2176876031, num_stripes=2
sie 07 04:45:06 pps kernel: BTRFS critical (device dm-1): stripe index math went horribly wrong, got stripe_index=2176876031, num_stripes=2
sie 07 04:45:06 pps kernel: BTRFS critical (device dm-1): stripe index math went horribly wrong, got stripe_index=2176876031, num_stripes=2
sie 07 04:45:06 pps kernel: BTRFS critical (device dm-1): stripe index math went horribly wrong, got stripe_index=2176876031, num_stripes=2
sie 07 04:45:06 pps kernel: BTRFS critical (device dm-1): stripe index math went horribly wrong, got stripe_index=2176876031, num_stripes=2
sie 07 04:45:06 pps kernel: BTRFS critical (device dm-1): stripe index math went horribly wrong, got stripe_index=2176876031, num_stripes=2
sie 07 04:45:06 pps kernel: BTRFS critical (device dm-1): stripe index math went horribly wrong, got stripe_index=2176876031, num_stripes=2
sie 07 04:45:06 pps kernel: BTRFS critical (device dm-1): stripe index math went horribly wrong, got stripe_index=2176876031, num_stripes=2
sie 07 04:45:06 pps kernel: BTRFS critical (device dm-1): stripe index math went horribly wrong, got stripe_index=2176876031, num_stripes=2
sie 07 04:45:06 pps kernel: BTRFS critical (device dm-1): stripe index math went horribly wrong, got stripe_index=2176876031, num_stripes=2
sie 07 04:45:06 pps kernel: BTRFS critical (device dm-1): stripe index math went horribly wrong, got stripe_index=2176876031, num_stripes=2
sie 07 04:45:06 pps kernel: BTRFS critical (device dm-1): stripe index math went horribly wrong, got stripe_index=2176876031, num_stripes=2
sie 07 04:45:06 pps kernel: BTRFS critical (device dm-1): stripe index math went horribly wrong, got stripe_index=2176876031, num_stripes=2
sie 07 04:45:06 pps kernel: BTRFS critical (device dm-1): stripe index math went horribly wrong, got stripe_index=2176876031, num_stripes=2
sie 07 04:45:06 pps kernel: BTRFS critical (device dm-1): stripe index math went horribly wrong, got stripe_index=2176876031, num_stripes=2
sie 07 04:45:06 pps kernel: BTRFS critical (device dm-1): stripe index math went horribly wrong, got stripe_index=2176876031, num_stripes=2
sie 07 04:45:06 pps kernel: BTRFS critical (device dm-1): stripe index math went horribly wrong, got stripe_index=2176876031, num_stripes=2
sie 07 04:45:06 pps kernel: BTRFS critical (device dm-1): stripe index math went horribly wrong, got stripe_index=2176876031, num_stripes=2
sie 07 04:45:06 pps kernel: BTRFS critical (device dm-1): stripe index math went horribly wrong, got stripe_index=2176876031, num_stripes=2
sie 07 04:45:06 pps kernel: BTRFS critical (device dm-1): stripe index math went horribly wrong, got stripe_index=2176876031, num_stripes=2
sie 07 04:45:06 pps kernel: BTRFS critical (device dm-1): stripe index math went horribly wrong, got stripe_index=2176876031, num_stripes=2
sie 07 04:45:06 pps kernel: BTRFS critical (device dm-1): stripe index math went horribly wrong, got stripe_index=2176876031, num_stripes=2
sie 07 04:45:06 pps kernel: BTRFS critical (device dm-1): stripe index math went horribly wrong, got stripe_index=2176876031, num_stripes=2
sie 07 04:45:06 pps kernel: BTRFS critical (device dm-1): stripe index math went horribly wrong, got stripe_index=2176876031, num_stripes=2
sie 07 04:45:06 pps kernel: BTRFS critical (device dm-1): stripe index math went horribly wrong, got stripe_index=2176876031, num_stripes=2
sie 07 04:45:06 pps kernel: BTRFS critical (device dm-1): stripe index math went horribly wrong, got stripe_index=2176876031, num_stripes=2
sie 07 04:45:06 pps kernel: BTRFS critical (device dm-1): stripe index math went horribly wrong, got stripe_index=2176876031, num_stripes=2
sie 07 04:45:06 pps kernel: BTRFS info (device dm-1): csum failed ino 1340360 extent 5370531217408 csum 716315696 wanted 722897355 mirror -2118091264
sie 07 04:45:06 pps kernel: kernel BUG at /build/linux-H5UzH8/linux-4.10.0/fs/btrfs/extent_io.c:2318!
sie 07 04:45:06 pps kernel: invalid opcode: 0000 [#1] SMP
sie 07 04:45:06 pps kernel: Modules linked in: xt_CHECKSUM ipt_MASQUERADE nf_nat_masquerade_ipv4 xt_tcpudp bridge stp llc ip6table_filter ip6table_nat nf_conntrack_ipv6 nf_defrag_ipv6 nf_nat_ipv6 ip6table_mangle ip6_tables iptable_filter iptable_nat nf_conntrack_ipv4 nf_defrag_ipv4 nf_nat_ipv4 nf_nat nf_conntrack libcrc32c iptable_mangle binfmt_misc intel_rapl intel_soc_dts_iosf intel_powerclamp ppdev coretemp kvm_intel snd_soc_rt5670 snd_intel_sst_acpi snd_soc_rt5645 kvm snd_intel_sst_core snd_soc_sst_mfld_platform snd_hda_codec_hdmi irqbypass snd_hda_codec_realtek snd_hda_codec_generic snd_soc_rt5640 punit_atom_debug snd_soc_sst_match crct10dif_pclmul crc32_pclmul snd_soc_rl6231 ghash_clmulni_intel snd_soc_core snd_hda_intel cryptd snd_hda_codec snd_compress snd_hda_core ac97_bus intel_cstate snd_pcm_dmaengine
sie 07 04:45:06 pps kernel:  snd_hwdep hci_uart btbcm btqca btintel snd_pcm lpc_ich dw_dmac bluetooth rfkill_gpio 8250_dw dw_dmac_core spi_pxa2xx_platform parport_pc snd_timer snd pwm_lpss_platform mac_hid parport mei_txe mei soundcore i2c_designware_platform i2c_designware_core pwm_lpss shpchp sunrpc w83627ehf hwmon_vid ip_tables x_tables autofs4 btrfs xor raid6_pq 9pnet_virtio 9p 9pnet fscache uas usb_storage i915 i2c_algo_bit drm_kms_helper syscopyarea sysfillrect sysimgblt fb_sys_fops r8169 drm mii ahci libahci video fjes i2c_hid hid sdhci_acpi sdhci
sie 07 04:45:06 pps kernel: CPU: 3 PID: 7259 Comm: kworker/u8:6 Not tainted 4.10.0-30-generic #34-Ubuntu
sie 07 04:45:06 pps kernel: Hardware name: To Be Filled By O.E.M. To Be Filled By O.E.M./Q1900DC-ITX, BIOS P1.20 07/08/2014
sie 07 04:45:06 pps kernel: Workqueue: btrfs-endio btrfs_endio_helper [btrfs]
sie 07 04:45:06 pps kernel: task: ffff883849279540 task.stack: ffffa4f6c212c000
sie 07 04:45:06 pps kernel: RIP: 0010:btrfs_check_repairable+0xf2/0x100 [btrfs]
sie 07 04:45:06 pps kernel: RSP: 0018:ffffa4f6c212fcf0 EFLAGS: 00010a83
sie 07 04:45:06 pps kernel: RAX: 0000000000000001 RBX: ffff8839437de580 RCX: 0000000000000002
sie 07 04:45:06 pps kernel: RDX: 0000000000000002 RSI: 0000000000000000 RDI: ffff8839745fae58
sie 07 04:45:06 pps kernel: RBP: ffffa4f6c212fd10 R08: 000004e243b00000 R09: 000004e283b00000
sie 07 04:45:06 pps kernel: R10: ffff8837957c4360 R11: 000000004e980780 R12: 000000004e980780
sie 07 04:45:06 pps kernel: R13: ffff8839745fa000 R14: ffff88394e981328 R15: ffff8837533c2ff0
sie 07 04:45:06 pps kernel: FS:  0000000000000000(0000) GS:ffff88397fd80000(0000) knlGS:0000000000000000
sie 07 04:45:06 pps kernel: CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
sie 07 04:45:06 pps kernel: CR2: 00007f035058e3a0 CR3: 0000000008c09000 CR4: 00000000001006e0
sie 07 04:45:06 pps kernel: Call Trace:
sie 07 04:45:06 pps kernel:  end_bio_extent_readpage+0x419/0x5b0 [btrfs]
sie 07 04:45:06 pps kernel:  bio_endio+0x56/0x60
sie 07 04:45:06 pps kernel:  end_workqueue_fn+0x3c/0x40 [btrfs]
sie 07 04:45:06 pps kernel:  btrfs_scrubparity_helper+0xc8/0x2e0 [btrfs]
sie 07 04:45:06 pps kernel:  btrfs_endio_helper+0xe/0x10 [btrfs]
sie 07 04:45:06 pps kernel:  process_one_work+0x1fc/0x4b0
sie 07 04:45:06 pps kernel:  worker_thread+0x4b/0x500
sie 07 04:45:06 pps kernel:  kthread+0x109/0x140
sie 07 04:45:06 pps kernel:  ? process_one_work+0x4b0/0x4b0
sie 07 04:45:06 pps kernel:  ? kthread_create_on_node+0x60/0x60
sie 07 04:45:06 pps kernel:  ret_from_fork+0x2c/0x40
sie 07 04:45:06 pps kernel: Code: 43 28 00 00 00 00 b9 01 00 00 00 31 c0 eb d5 8d 48 02 eb d9 45 89 e0 48 c7 c6 90 74 73 c0 4c 89 ef e8 93 a7 fa ff e9 78 ff ff ff <0f> 0b 66 90 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 55 48 
sie 07 04:45:06 pps kernel: RIP: btrfs_check_repairable+0xf2/0x100 [btrfs] RSP: ffffa4f6c212fcf0
sie 07 04:45:06 pps kernel: ------------[ cut here ]------------

Re: kernel BUG at /build/linux-H5UzH8/linux-4.10.0/fs/btrfs/extent_io.c:2318

[Duncan]

Piotr Pawłow posted on Mon, 07 Aug 2017 15:26:16 +0200 as excerpted:

> # uname -a
> Linux pps 4.10.0-30-generic #34-Ubuntu SMP
> Mon Jul 31 19:38:17 UTC 2017 x86_64 x86_64 x86_64 GNU/Linux

This is a general principles reply and chances are wouldn't help with 
your issue since the spread isn't /too/ large yet and I've no knowledge 
of a specific fix for your issue in newer kernels, but FWIW...

This being the btrfs development list and btrfs, while stabilizing (but 
not yet to be considered fully stable) still being under rather intense 
development, with significant changes every kernel cycle, list focus 
tends to be quite forward looking, with most interest and the best chance 
of fixes on relatively current kernels.

What we try to support, in addition to development kernels, is the latest 
two release kernel series in two tracks, (mainline/Linus) current and LTS.

On the current track, 4.12 is the newest release so 4.12 and 4.11 are 
best supported, tho the 4.11 series is already listed as EOL on 
kernel.org.  On the LTS track, 4.9 and 4.4 are the latest LTS releases, 
with 4.1 the previous one but already well out of btrfs focus range.

That puts 4.10 out of the list's best-supported focus range, with 4.11 
still in focus but EOL.  Beyond that we still try, but you're not as 
likely to get interest from the developers themselves, and for the other 
btrfs-user-regulars here, as the spread gets wider, the support gets more 
difficult as it's harder to remember where things were back then.

So the recommendation would be to either upgrade to 4.12 current if you 
want to stay on current track, or downgrade to the latest 4.9 release if 
you prefer stable track.

Other alternatives would include getting support from your distro if 
you're running a distro kernel (as seems to be your case), since they 
know what they've backported and what they haven't, and are thus in a 
better position to support it, and of course, simply sticking with what 
you have and accepting that you won't get quite the support or interest 
on your list posts since you're out of primary focus range.

Of course you can also keep a current kernel available and boot to it to 
try to duplicate any issues before reporting, while otherwise sticking to 
your older kernel, but unless you have a specific reason to do that, it 
would seem more trouble than simply running the current kernel by default.

So 4.10 isn't /too/ far out of range yet, but I'd strongly consider 
upgrading (or downgrading to 4.9 LTS) as soon as it's reasonably 
convenient, before 4.13 in any case.  Unless you prefer to go the distro 
support route, of course.

-- 
Duncan - List replies preferred.   No HTML msgs.
"Every nonfree program has a lord, a master --
and if you use the program, he is your master."  Richard Stallman

Re: kernel BUG at /build/linux-H5UzH8/linux-4.10.0/fs/btrfs/extent_io.c:2318

[Piotr Pawłow]

Hello,
> So 4.10 isn't /too/ far out of range yet, but I'd strongly consider 
> upgrading (or downgrading to 4.9 LTS) as soon as it's reasonably 
> convenient, before 4.13 in any case.  Unless you prefer to go the 
> distro support route, of course.

I used to stick to latest kernels back when btrfs wasn't as stable and
there were frequently important bug fixes. Nowadays I had no problems
since such a long time, that I forgot to change the kernel after
upgrading the distro. Besides, I thought RAID-1 was stable years ago
(except the degraded mount issue).

Anyway, after I took care of bad blocks by remapping them, scrub fixed
all corruptions without any problems. Fsck comes out clean and
everything seems fine.

Re: kernel BUG at /build/linux-H5UzH8/linux-4.10.0/fs/btrfs/extent_io.c:2318

[Austin S. Hemmelgarn]

On 2017-08-11 05:57, Piotr Pawłow wrote:
> Hello,
>> So 4.10 isn't /too/ far out of range yet, but I'd strongly consider
>> upgrading (or downgrading to 4.9 LTS) as soon as it's reasonably
>> convenient, before 4.13 in any case.  Unless you prefer to go the
>> distro support route, of course.
> 
> I used to stick to latest kernels back when btrfs wasn't as stable and
> there were frequently important bug fixes. Nowadays I had no problems
> since such a long time, that I forgot to change the kernel after
> upgrading the distro. Besides, I thought RAID-1 was stable years ago
> (except the degraded mount issue).
So, just my thoughts on this in particular.  Either you are staying 
absolutely up to date (which I would still recommend if possible, there 
are new fixes going in regularly still, and we've been seing some 
performance improvements recently too), or you're not.  If you're not, 
you should either:
1. Stick to upstream (kernel.org) LTS releases (and still ideally stay 
up to date within that release) and get reasonably reliable help from 
the ML.
2. Stick to your distribution's kernels, and get help from your 
distribution's usual support channels.

As far as raid1 mode, it generally is reasonably stable, but there are 
still edge cases we with bugs that haven't been found (as you found out 
here).
> 
> Anyway, after I took care of bad blocks by remapping them, scrub fixed
> all corruptions without any problems. Fsck comes out clean and
> everything seems fine.
Glad to hear everything is working now!