Freeze issues with BTRFS and Timeshift

Does anyone know if there are confirmed problems with BTRFS and Timeshift snapshots causing the system to freeze up? I 'm having this problem where the desktop will freeze for long periods (several minutes), without any particular demand neither on the CPU nor on the disk. It will then unfreeze for a short period and then freeze back.

I once managed to fix the issue by running “timeshift --check”, which got rid of corrupted/incomplete snapshots and resumed my system to normal. But this time the situation was so bad that I had to turn-off using the power button in the middle of the checking/fixing procedure, which caused corruption so bad my system does not boot anymore.

I wonder if anyone else has experienced similar problems while using BTRFS and very frequent timeshift snapshots (I was running mine on an hourly basis).

Thanks a lot.

This tends to break btrfs (but also most of othe filesystems as well), you better have an external backup for such cases.

Sure, I was quite concerned when I had to power down in the middle of a checking procedure, but the system was frozen…

I don’t know if this problem is being caused by btrfs or by timeshift, or some kind of conjunction of the two together.

Would anyone know if running snapshots on an hourly basis causes some kind of file system instability?

It is btrfs that causes issues. It sometimes gets corrupted in the extent tree and then you can only format and restore from an external backup.

1 Like

I ended up with a dirty filesystem, with a number of “extent holes” that do not get repaired even with the --repair option. Will try the “–init-extent-tree” from live distro later.

I wonder how btrfs has some major sponsors such as OpenSUSE and Synology, if it is not stable yet even on a simple notebook. I thought to myself: If Synology uses it on their commercial NAS systems, then it must be stable enough for me to run on a notebook…

Maybe they use some more stable version than we have here at Manjaro??

I warn you that it will take very long, several days. And it probably won’t repair the damage anyway. Do it only if you have a different machine to work on. You can run it only from a different OS (Manjaro live USB e.g.)

I think in a professional scenario the admin will set up proper backup, not just rely on btrfs snapshots. But the snapshots are nice (when they work).

Thanks Eugen. Makes me think twice… The system is working now, despite de dirty filesystem. If I could know that the the existing “extent hole” errors will not propagate causing further problems, I think I would leave them as they are…

Hi Eugen. Still having some freeze issues but they seem fewer and farther in between this week, following what seemed a partially successful “btrfsck --repair” from live distro last week. I now managed to get dmesg output right after the computer returned to normal and found this:

[  860.095932] baloo_file_extr D    0  1750   1653 0x00004080
[  860.095934] Call Trace:
[  860.095941]  __schedule+0x2a7/0x7e0
[  860.095944]  schedule+0x43/0xd0
[  860.095971]  btrfs_start_ordered_extent+0x12f/0x160 [btrfs]
[  860.095975]  ? wait_woken+0x80/0x80
[  860.095992]  btrfs_wait_ordered_range+0x92/0x110 [btrfs]
[  860.096007]  btrfs_sync_file+0x217/0x440 [btrfs]
[  860.096012]  __x64_sys_fdatasync+0x47/0x80
[  860.096015]  do_syscall_64+0x49/0x90
[  860.096017]  entry_SYSCALL_64_after_hwframe+0x44/0xa9
[  860.096019] RIP: 0033:0x7fc429328e4b
[  860.096023] Code: Bad RIP value.
[  860.096024] RSP: 002b:00007ffe190c4960 EFLAGS: 00000293 ORIG_RAX: 000000000000004b
[  860.096025] RAX: ffffffffffffffda RBX: 000055f0e01aeee0 RCX: 00007fc429328e4b
[  860.096026] RDX: 0000000000000002 RSI: 0000000000000000 RDI: 000000000000000c
[  860.096027] RBP: 000055f0e27c6788 R08: 0000000000000000 R09: 0000000000001a8e
[  860.096027] R10: 00000000c1a4e000 R11: 0000000000000293 R12: 00007ffe190c4a10
[  860.096028] R13: 000055f0e01b4b80 R14: 0000000000000000 R15: 0000000000000000
[  915.261260] systemd[1]: systemd-tmpfiles-clean.service: Succeeded.
[  915.261611] systemd[1]: Finished Cleanup of Temporary Directories.
[  915.261791] audit: type=1130 audit(1599914155.225:103): pid=1 uid=0 auid=4294967295 ses=4294967295 subj==unconfined msg='unit=systemd-tmpfiles-clean comm="systemd" exe="/usr/lib/systemd/systemd" hostname=? addr=? terminal=? res=success'
[  915.261795] audit: type=1131 audit(1599914155.225:104): pid=1 uid=0 auid=4294967295 ses=4294967295 subj==unconfined msg='unit=systemd-tmpfiles-clean comm="systemd" exe="/usr/lib/systemd/systemd" hostname=? addr=? terminal=? res=success'
[  982.975759] INFO: task kworker/u16:0:7 blocked for more than 122 seconds.
[  982.975761]       Tainted: G           OE     5.4.64-1-MANJARO #1
[  982.975762] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[  982.975763] kworker/u16:0   D    0     7      2 0x80004000
[  982.975797] Workqueue: btrfs-endio-write btrfs_work_helper [btrfs]
[  982.975798] Call Trace:
[  982.975804]  __schedule+0x2a7/0x7e0
[  982.975806]  schedule+0x43/0xd0
[  982.975822]  wait_current_trans+0xdf/0x120 [btrfs]
[  982.975826]  ? wait_woken+0x80/0x80
[  982.975840]  start_transaction+0x331/0x520 [btrfs]
[  982.975857]  btrfs_finish_ordered_io.isra.0+0x339/0x820 [btrfs]
[  982.975876]  btrfs_work_helper+0xde/0x400 [btrfs]
[  982.975880]  process_one_work+0x1e1/0x3d0
[  982.975882]  worker_thread+0x4d/0x3e0
[  982.975884]  ? rescuer_thread+0x3f0/0x3f0
[  982.975885]  kthread+0x13e/0x160
[  982.975887]  ? __kthread_bind_mask+0x60/0x60
[  982.975890]  ret_from_fork+0x1f/0x40
[  982.975905] INFO: task kworker/u16:2:217 blocked for more than 122 seconds.
[  982.975905]       Tainted: G           OE     5.4.64-1-MANJARO #1
[  982.975906] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[  982.975907] kworker/u16:2   D    0   217      2 0x80004000
[  982.975927] Workqueue: btrfs-delalloc btrfs_work_helper [btrfs]
[  982.975928] Call Trace:
[  982.975930]  __schedule+0x2a7/0x7e0
[  982.975932]  schedule+0x43/0xd0
[  982.975946]  wait_current_trans+0xdf/0x120 [btrfs]
[  982.975948]  ? wait_woken+0x80/0x80
[  982.975962]  start_transaction+0x331/0x520 [btrfs]
[  982.975977]  cow_file_range_inline.constprop.0+0xec/0x670 [btrfs]
[  982.975980]  ? _raw_spin_lock_bh+0x13/0x30
[  982.975982]  ? __local_bh_enable_ip+0x33/0x70
[  982.976000]  ? zstd_put_workspace+0x6e/0x120 [btrfs]
[  982.976018]  ? btrfs_compress_pages+0x77/0xa0 [btrfs]
[  982.976033]  compress_file_range+0x414/0x810 [btrfs]
[  982.976048]  ? submit_compressed_extents+0x410/0x410 [btrfs]
[  982.976065]  async_cow_start+0x12/0x30 [btrfs]
[  982.976088]  btrfs_work_helper+0xde/0x400 [btrfs]
[  982.976091]  process_one_work+0x1e1/0x3d0
[  982.976093]  worker_thread+0x4d/0x3e0
[  982.976095]  ? rescuer_thread+0x3f0/0x3f0
[  982.976096]  kthread+0x13e/0x160
[  982.976098]  ? __kthread_bind_mask+0x60/0x60
[  982.976100]  ret_from_fork+0x1f/0x40
[  982.976107] INFO: task kworker/u16:6:267 blocked for more than 122 seconds.
[  982.976108]       Tainted: G           OE     5.4.64-1-MANJARO #1
[  982.976108] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[  982.976109] kworker/u16:6   D    0   267      2 0x80004000
[  982.976127] Workqueue: btrfs-endio-write btrfs_work_helper [btrfs]
[  982.976128] Call Trace:
[  982.976130]  __schedule+0x2a7/0x7e0
[  982.976132]  schedule+0x43/0xd0
[  982.976146]  wait_current_trans+0xdf/0x120 [btrfs]
[  982.976148]  ? wait_woken+0x80/0x80
[  982.976161]  start_transaction+0x331/0x520 [btrfs]
[  982.976176]  btrfs_finish_ordered_io.isra.0+0x339/0x820 [btrfs]
[  982.976193]  btrfs_work_helper+0xde/0x400 [btrfs]
[  982.976196]  process_one_work+0x1e1/0x3d0
[  982.976198]  worker_thread+0x4d/0x3e0
[  982.976200]  ? rescuer_thread+0x3f0/0x3f0
[  982.976201]  kthread+0x13e/0x160
[  982.976203]  ? __kthread_bind_mask+0x60/0x60
[  982.976205]  ret_from_fork+0x1f/0x40
[  982.976207] INFO: task kworker/u16:7:268 blocked for more than 122 seconds.
[  982.976208]       Tainted: G           OE     5.4.64-1-MANJARO #1
[  982.976209] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[  982.976209] kworker/u16:7   D    0   268      2 0x80004000
[  982.976227] Workqueue: btrfs-delalloc btrfs_work_helper [btrfs]
[  982.976228] Call Trace:
[  982.976230]  __schedule+0x2a7/0x7e0
[  982.976232]  schedule+0x43/0xd0
[  982.976245]  wait_current_trans+0xdf/0x120 [btrfs]
[  982.976247]  ? wait_woken+0x80/0x80
[  982.976260]  start_transaction+0x331/0x520 [btrfs]
[  982.976274]  cow_file_range_inline.constprop.0+0xec/0x670 [btrfs]
[  982.976276]  ? _raw_spin_lock_bh+0x13/0x30
[  982.976278]  ? __local_bh_enable_ip+0x33/0x70
[  982.976296]  ? zstd_put_workspace+0x6e/0x120 [btrfs]
[  982.976313]  ? btrfs_compress_pages+0x77/0xa0 [btrfs]
[  982.976327]  compress_file_range+0x414/0x810 [btrfs]
[  982.976342]  ? submit_compressed_extents+0x410/0x410 [btrfs]
[  982.976355]  async_cow_start+0x12/0x30 [btrfs]
[  982.976372]  btrfs_work_helper+0xde/0x400 [btrfs]
[  982.976375]  process_one_work+0x1e1/0x3d0
[  982.976377]  worker_thread+0x4d/0x3e0
[  982.976379]  ? rescuer_thread+0x3f0/0x3f0
[  982.976380]  kthread+0x13e/0x160
[  982.976381]  ? __kthread_bind_mask+0x60/0x60
[  982.976384]  ret_from_fork+0x1f/0x40
[  982.976386] INFO: task kworker/u16:8:269 blocked for more than 122 seconds.
[  982.976387]       Tainted: G           OE     5.4.64-1-MANJARO #1
[  982.976387] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[  982.976388] kworker/u16:8   D    0   269      2 0x80004000
[  982.976405] Workqueue: btrfs-endio-write btrfs_work_helper [btrfs]
[  982.976406] Call Trace:
[  982.976408]  __schedule+0x2a7/0x7e0
[  982.976410]  schedule+0x43/0xd0
[  982.976423]  wait_current_trans+0xdf/0x120 [btrfs]
[  982.976425]  ? wait_woken+0x80/0x80
[  982.976438]  start_transaction+0x331/0x520 [btrfs]
[  982.976453]  btrfs_finish_ordered_io.isra.0+0x339/0x820 [btrfs]
[  982.976470]  btrfs_work_helper+0xde/0x400 [btrfs]
[  982.976473]  process_one_work+0x1e1/0x3d0
[  982.976475]  ? rescuer_thread+0x3f0/0x3f0
[  982.976476]  worker_thread+0x4d/0x3e0
[  982.976478]  ? rescuer_thread+0x3f0/0x3f0
[  982.976479]  kthread+0x13e/0x160
[  982.976480]  ? __kthread_bind_mask+0x60/0x60
[  982.976483]  ret_from_fork+0x1f/0x40
[  982.976485] INFO: task kworker/u16:9:288 blocked for more than 122 seconds.
[  982.976486]       Tainted: G           OE     5.4.64-1-MANJARO #1
[  982.976486] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[  982.976487] kworker/u16:9   D    0   288      2 0x80004000
[  982.976504] Workqueue: btrfs-endio-write btrfs_work_helper [btrfs]
[  982.976505] Call Trace:
[  982.976507]  __schedule+0x2a7/0x7e0
[  982.976509]  schedule+0x43/0xd0
[  982.976522]  wait_current_trans+0xdf/0x120 [btrfs]
[  982.976524]  ? wait_woken+0x80/0x80
[  982.976537]  start_transaction+0x331/0x520 [btrfs]
[  982.976552]  btrfs_finish_ordered_io.isra.0+0x339/0x820 [btrfs]
[  982.976569]  btrfs_work_helper+0xde/0x400 [btrfs]
[  982.976571]  process_one_work+0x1e1/0x3d0
[  982.976573]  ? rescuer_thread+0x3f0/0x3f0
[  982.976574]  worker_thread+0x4d/0x3e0
[  982.976576]  ? rescuer_thread+0x3f0/0x3f0
[  982.976577]  kthread+0x13e/0x160
[  982.976579]  ? __kthread_bind_mask+0x60/0x60
[  982.976581]  ret_from_fork+0x1f/0x40
[  982.976583] INFO: task systemd-journal:298 blocked for more than 122 seconds.
[  982.976584]       Tainted: G           OE     5.4.64-1-MANJARO #1
[  982.976584] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[  982.976585] systemd-journal D    0   298      1 0x00000324
[  982.976586] Call Trace:
[  982.976588]  __schedule+0x2a7/0x7e0
[  982.976590]  schedule+0x43/0xd0
[  982.976603]  wait_current_trans+0xdf/0x120 [btrfs]
[  982.976605]  ? wait_woken+0x80/0x80
[  982.976618]  start_transaction+0x480/0x520 [btrfs]
[  982.976632]  btrfs_setattr+0x14a/0x5e0 [btrfs]
[  982.976636]  notify_change+0x33b/0x4a0
[  982.976638]  ? cap_inode_need_killpriv+0x1a/0x30
[  982.976641]  do_truncate+0x88/0xe0
[  982.976644]  do_sys_ftruncate+0xfd/0x110
[  982.976647]  do_syscall_64+0x49/0x90
[  982.976650]  entry_SYSCALL_64_after_hwframe+0x44/0xa9
[  982.976651] RIP: 0033:0x7fd279e9556b
[  982.976655] Code: Bad RIP value.
[  982.976656] RSP: 002b:00007ffc43026008 EFLAGS: 00000206 ORIG_RAX: 000000000000004d
[  982.976657] RAX: ffffffffffffffda RBX: 00007ffc43026040 RCX: 00007fd279e9556b
[  982.976658] RDX: 00005617ac94c310 RSI: 0000000008000000 RDI: 0000000000000017
[  982.976659] RBP: 00005617ac94c500 R08: 0000000000000001 R09: 00005617ac94c584
[  982.976660] R10: 0000000000000000 R11: 0000000000000206 R12: 00007ffc43026038
[  982.976660] R13: 0000000000000003 R14: 0000000000000000 R15: 0000000000000000
[  982.976664] INFO: task kworker/u16:10:420 blocked for more than 122 seconds.
[  982.976665]       Tainted: G           OE     5.4.64-1-MANJARO #1
[  982.976665] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[  982.976666] kworker/u16:10  D    0   420      2 0x80004080
[  982.976684] Workqueue: btrfs-endio-write btrfs_work_helper [btrfs]
[  982.976684] Call Trace:
[  982.976687]  __schedule+0x2a7/0x7e0
[  982.976689]  schedule+0x43/0xd0
[  982.976702]  wait_current_trans+0xdf/0x120 [btrfs]
[  982.976704]  ? wait_woken+0x80/0x80
[  982.976717]  start_transaction+0x331/0x520 [btrfs]
[  982.976731]  btrfs_finish_ordered_io.isra.0+0x339/0x820 [btrfs]
[  982.976748]  btrfs_work_helper+0xde/0x400 [btrfs]
[  982.976751]  process_one_work+0x1e1/0x3d0
[  982.976753]  ? rescuer_thread+0x3f0/0x3f0
[  982.976754]  worker_thread+0x4d/0x3e0
[  982.976756]  ? rescuer_thread+0x3f0/0x3f0
[  982.976757]  kthread+0x13e/0x160
[  982.976759]  ? __kthread_bind_mask+0x60/0x60
[  982.976761]  ret_from_fork+0x1f/0x40
[  982.976784] INFO: task kwin_x11:1441 blocked for more than 122 seconds.
[  982.976784]       Tainted: G           OE     5.4.64-1-MANJARO #1
[  982.976785] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[  982.976785] kwin_x11        D    0  1441      1 0x00000080
[  982.976787] Call Trace:
[  982.976789]  __schedule+0x2a7/0x7e0
[  982.976791]  schedule+0x43/0xd0
[  982.976804]  wait_current_trans+0xdf/0x120 [btrfs]
[  982.976806]  ? wait_woken+0x80/0x80
[  982.976819]  start_transaction+0x331/0x520 [btrfs]
[  982.976834]  btrfs_dirty_inode+0x44/0xd0 [btrfs]
[  982.976836]  file_update_time+0x105/0x150
[  982.976851]  btrfs_page_mkwrite+0xfe/0x4e0 [btrfs]
[  982.976855]  do_page_mkwrite+0x56/0xb0
[  982.976857]  do_wp_page+0x3ee/0x550
[  982.976859]  __handle_mm_fault+0xd7f/0x16c0
[  982.976862]  handle_mm_fault+0xca/0x1f0
[  982.976864]  do_user_addr_fault+0x1ef/0x470
[  982.976867]  ? syscall_slow_exit_work+0x134/0x160
[  982.976868]  page_fault+0x34/0x40
[  982.976870] RIP: 0033:0x7f667900ffe5
[  982.976872] Code: Bad RIP value.
[  982.976873] RSP: 002b:00007ffe9afba000 EFLAGS: 00010246
[  982.976874] RAX: 0000000000000000 RBX: 00000000000005a1 RCX: 0000000000000000
[  982.976874] RDX: 0000000000000001 RSI: 0000000000000000 RDI: 00007f65b778e008
[  982.976875] RBP: 00007f65b778e008 R08: 000055a547b009f0 R09: 00007ffe9afba198
[  982.976876] R10: 00007ffe9afba130 R11: 00007ffe9afba120 R12: 00007ffe9afba070
[  982.976876] R13: 0000000000000000 R14: 00007f65b778e018 R15: 00007ffe9afba300
[  995.009335] audit: type=1701 audit(1599914234.975:105): auid=4294967295 uid=0 gid=0 ses=4294967295 subj==unconfined pid=298 comm="systemd-journal" exe="/usr/lib/systemd/systemd-journald" sig=6 res=1
[  995.053215] systemd[1]: systemd-journald.service: Main process exited, code=dumped, status=6/ABRT
[  995.053295] systemd[1]: systemd-journald.service: Failed with result 'watchdog'.
[  995.053946] audit: type=1131 audit(1599914235.019:106): pid=1 uid=0 auid=4294967295 ses=4294967295 subj==unconfined msg='unit=systemd-journald comm="systemd" exe="/usr/lib/systemd/systemd" hostname=? addr=? terminal=? res=failed'
[  995.054991] systemd[1]: systemd-journald.service: Scheduled restart job, restart counter is at 1.
[  995.056582] systemd[1]: Stopping Flush Journal to Persistent Storage...
[  995.062197] systemd[1]: systemd-journal-flush.service: Succeeded.
[  995.062706] systemd[1]: Stopped Flush Journal to Persistent Storage.
[  995.062769] audit: type=1131 audit(1599914235.029:107): pid=1 uid=0 auid=4294967295 ses=4294967295 subj==unconfined msg='unit=systemd-journal-flush comm="systemd" exe="/usr/lib/systemd/systemd" hostname=? addr=? terminal=? res=success'
[  995.063151] systemd[1]: Stopped Journal Service.
[  995.063221] audit: type=1130 audit(1599914235.029:108): pid=1 uid=0 auid=4294967295 ses=4294967295 subj==unconfined msg='unit=systemd-journald comm="systemd" exe="/usr/lib/systemd/systemd" hostname=? addr=? terminal=? res=success'
[  995.063224] audit: type=1131 audit(1599914235.029:109): pid=1 uid=0 auid=4294967295 ses=4294967295 subj==unconfined msg='unit=systemd-journald comm="systemd" exe="/usr/lib/systemd/systemd" hostname=? addr=? terminal=? res=success'
[  995.065505] systemd[1]: Starting Journal Service...
[  995.412503] audit: type=1305 audit(1599914235.379:110): op=set audit_enabled=1 old=1 auid=4294967295 ses=4294967295 subj==unconfined res=1
[ 1011.274805] systemd-coredump[4966]: Process 298 (systemd-journal) of user 0 dumped core.
[ 1011.274811] systemd-coredump[4966]: Coredump diverted to /var/lib/systemd/coredump/core.systemd-journal.0.64087648dba94698a6e063a6ed522277.298.1599914234000000.zst
[ 1011.274813] systemd-coredump[4966]: Stack trace of thread 298:
[ 1011.274815] systemd-coredump[4966]: #0  0x00007fd279e9556b ftruncate64 (libc.so.6 + 0xf956b)
[ 1011.274817] systemd-coredump[4966]: #1  0x00007fd27a14965e journal_file_post_change (libsystemd-shared-246.so + 0x1ae65e)
[ 1011.274819] systemd-coredump[4966]: #2  0x00007fd27a1496e2 n/a (libsystemd-shared-246.so + 0x1ae6e2)
[ 1011.274821] systemd-coredump[4966]: #3  0x00007fd27a14237e n/a (libsystemd-shared-246.so + 0x1a737e)
[ 1011.274823] systemd-coredump[4966]: #4  0x00007fd27a14271b sd_event_dispatch (libsystemd-shared-246.so + 0x1a771b)
[ 1011.274825] systemd-coredump[4966]: #5  0x00007fd27a143a61 sd_event_run (libsystemd-shared-246.so + 0x1a8a61)
[ 1011.274827] systemd-coredump[4966]: #6  0x00005617ac20c1f6 n/a (systemd-journald + 0x61f6)
[ 1011.274829] systemd-coredump[4966]: #7  0x00007fd279dc4152 __libc_start_main (libc.so.6 + 0x28152)
[ 1011.274831] systemd-coredump[4966]: #8  0x00005617ac20c91e n/a (systemd-journald + 0x691e)
[ 1033.343298] audit: type=1100 audit(1599914273.309:111): pid=5093 uid=1000 auid=1000 ses=2 subj==unconfined msg='op=PAM:authentication grantors=pam_faillock,pam_permit,pam_faillock acct="gustavo" exe="/usr/bin/sudo" hostname=? addr=? terminal=/dev/pts/1 res=success'
[ 1033.344593] audit: type=1101 audit(1599914273.309:112): pid=5093 uid=1000 auid=1000 ses=2 subj==unconfined msg='op=PAM:accounting grantors=pam_permit,pam_time acct="gustavo" exe="/usr/bin/sudo" hostname=? addr=? terminal=/dev/pts/1 res=success'
[ 1033.344775] audit: type=1110 audit(1599914273.309:113): pid=5093 uid=0 auid=1000 ses=2 subj==unconfined msg='op=PAM:setcred grantors=pam_faillock,pam_permit,pam_faillock acct="root" exe="/usr/bin/sudo" hostname=? addr=? terminal=/dev/pts/1 res=success'
[ 1033.347897] audit: type=1105 audit(1599914273.312:114): pid=5093 uid=0 auid=1000 ses=2 subj==unconfined msg='op=PAM:session_open grantors=pam_limits,pam_unix,pam_permit acct="root" exe="/usr/bin/sudo" hostname=? addr=? terminal=/dev/pts/1 res=success'

Interestingly, while the computer was frozen, I noticed hardly no disk activity at all (this notebook has a LED that flashes on disk access), so it did not look as if btrfs was doing any house cleaning either. It just completely froze…

Do you understand what this log talks about? (pretty much all of it is marked red in the original output). Thank you so much.

Another weekend toiling with this issue. It is now clear that the freezes relate to the snapshot creation process with Timeshift and btrfs

Hourly snapshots were bringing my computer to a total freeze. I reduced to only at boot, but even that causes the notebook to freeze for like 20 minutes, with a few short hiccups in the meantime, but mostly frozen all the way.

Disk activity remains very low during the freeze and CPU usage also seems to remain low. On some other forums (mostly SuSE) I found users having the exact same problem, but they tend to report high CPU usage with btrfs-transacti and btrfs-cleaner, none of which seem to be installed on Manjaro (I might be wrong).

This seems to be a relatively prevalent matter. I see numerous posts on google but none with a clear solution.