On 13.09.2018 11:34, Jürgen Herrmann wrote: > Hello! > > I have a newly installed laptop running a freshly installed (abt. two > months ago) laptop running latest linux mint 19. Root filesystem is on a > 1TB Samsung 860 M.2 SSD with btrfs on top of a LUKS encrypted 900G > partition. Timeshift-btrfs is enabled for root (@) and home (@home) > subvolumes. I want to transfer snapshots to a server with a separated > disk via "btrfs send" and ssh. > > Here's the list of snapshot directories, each containing tow snapshots > for root and home: > > drwxr-xr-x 1 root root 30 Sep 12 22:08 2018-08-16_20-00-01 > drwxr-xr-x 1 root root 30 Aug 17 14:00 2018-08-17_14-00-02 > drwxr-xr-x 1 root root 30 Aug 23 20:00 2018-08-23_20-00-01 > drwxr-xr-x 1 root root 30 Aug 30 20:00 2018-08-30_20-00-01 > drwxr-xr-x 1 root root 30 Sep 6 20:00 2018-09-06_20-00-01 > drwxr-xr-x 1 root root 30 Sep 6 22:00 2018-09-06_22-00-01 > drwxr-xr-x 1 root root 30 Sep 8 16:00 2018-09-08_16-00-01 > drwxr-xr-x 1 root root 30 Sep 10 20:00 2018-09-10_20-00-02 > drwxr-xr-x 1 root root 30 Sep 11 21:00 2018-09-11_21-00-02 > drwxr-xr-x 1 root root 30 Sep 12 21:00 2018-09-12_21-00-01 > > "btrfs send > /mnt/timeshift/backup/timeshift-btrfs/snapshots/2018-08-16_20-00-01/@ >>/dev/null" results in the btrfs task taking 100% cpu time on one cpu > and then all IO is blocked -> only reboot can solve the hang. > > The crash does not happen immediately, as i was on the road using > cellular connection it seemed fine at first. That's how I found out that > it transfers ~140MB of data before hanging. The snapshot is created on > the server and contains data (du shows abt 140MB). > > I am running vanilla kernel 4.18.6 (compiled by myself) and btrfs progs > 4.17.1 compiled from source. > > Here's the btrfs filesystem info: > Label: none uuid: a914c141-72bf-448b-847f-d64ee82d8b7b > Total devices 1 FS bytes used 342.85GiB > devid 1 size 875.44GiB used 357.05GiB path > /dev/mapper/sda3_crypt > > A scrub shows no errors: > scrub status for a914c141-72bf-448b-847f-d64ee82d8b7b > scrub started at Thu Sep 13 10:20:18 2018 and finished after > 00:12:19 > total bytes scrubbed: 342.78GiB with 0 errors > > What can I do to help debugging this issue? You should provide output of echo w > /proc/sysrq-trigger. Also sample the stack of /proc/[pid of btrfs send]/stack to see if it is changing. > > Best regards, > Jürgen
