Dear Btrfs Experts, I would like to ask for advice regarding the following problem:
I regularly do incremental backups of snapshots using commands like: btrfs send -p /volumes/root/snapshots/2018-08-02 /volumes/root/snapshots/2018-08-03 | btrfs receive /volumes/sj-backup/root Recently the command started hanging with the following message showing up in dmesg: [136055.426170] INFO: task btrfs-transacti:13368 blocked for more than 120 seconds. [136055.426181] Tainted: P OE 4.15.0-29-generic #31-Ubuntu [136055.426186] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [136055.426192] btrfs-transacti D 0 13368 2 0x80000000 [136055.426199] Call Trace: [136055.426215] __schedule+0x291/0x8a0 [136055.426224] schedule+0x2c/0x80 [136055.426283] btrfs_commit_transaction+0x81d/0x8f0 [btrfs] [136055.426291] ? wait_woken+0x80/0x80 [136055.426342] transaction_kthread+0x18d/0x1b0 [btrfs] [136055.426351] kthread+0x121/0x140 [136055.426395] ? btrfs_cleanup_transaction+0x560/0x560 [btrfs] [136055.426402] ? kthread_create_worker_on_cpu+0x70/0x70 [136055.426409] ret_from_fork+0x35/0x40 This message is repeated 6 times. The first time this happened, I waited a few hours for the command to finish (usually it only takes a few minutes), but finally I gave up waiting and rebooted. When I ran the command again, I got the same result. I have another backup disk stored in a different location and from time to time I swap them. I swapped them just to test whether the problem is on the sending or the receiving side and with the other disk everything works fine. I swapped them back and the problem returned. I have tried scrubbing the disk, it did not find any errors. Interestingly, when I removed a few older snapshots from the target disk, the command started working again, but a few days later, it started hanging again. While it was working, I removed some more older snapshots, which may or may not have been the trigger behind the problem resurfacing. I'm using Ubuntu 18.04, kernel 4.15.0-29-generic. Thanks, Zoltan -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
