Hello! I attempted to run btrfs balance, but it crashed soon after start. Status is stuck on this:
$ sudo btrfs balance status -v /data Balance on '/data' is running 0 out of about 10436 chunks balanced (1 considered), 100% left Dumping filters: flags 0x7, state 0x1, force is off DATA (flags 0x0): balancing METADATA (flags 0x0): balancing SYSTEM (flags 0x0): balancing Logs have the output below. How shall I read it and debug this situation? What are the next steps I could test/debug? kernel: BTRFS info (device dm-9): disk space caching is enabled kernel: BTRFS: has skinny extents kernel: BTRFS: checking UUID tree kernel: BTRFS info (device dm-9): relocating block group 13693423976448 flags 20 kernel: INFO: task btrfs:2918 blocked for more than 120 seconds. kernel: Not tainted 4.4.0-146-generic #172-Ubuntu kernel: "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. kernel: btrfs D ffff88030bd07a98 0 2918 2892 0x00000000 kernel: ffff88030bd07a98 ffffffff81197240 ffffffff81e13500 ffff88033fe44e00 kernel: ffff88030bd08000 ffff88035dc88714 ffff88033fe44e00 00000000ffffffff kernel: ffff88035dc88718 ffff88030bd07ab0 ffffffff8185e0b5 ffff88035dc88710 kernel: Call Trace: kernel: [<ffffffff81197240>] ? printk+0x5a/0x76 kernel: [<ffffffff8185e0b5>] schedule+0x35/0x80 kernel: [<ffffffff8185e40e>] schedule_preempt_disabled+0xe/0x10 kernel: [<ffffffff818602a7>] __mutex_lock_slowpath+0xb7/0x130 kernel: [<ffffffff8186033f>] mutex_lock+0x1f/0x30 kernel: [<ffffffffc047b01b>] btrfs_relocate_block_group+0x1ab/0x290 [btrfs] kernel: [<ffffffffc044fe47>] btrfs_relocate_chunk.isra.39+0x47/0xd0 [btrfs] kernel: [<ffffffffc04512fa>] __btrfs_balance+0x5ba/0xb90 [btrfs] kernel: [<ffffffffc0451b60>] btrfs_balance+0x290/0x5f0 [btrfs] kernel: [<ffffffffc045d031>] btrfs_ioctl_balance+0x381/0x390 [btrfs] kernel: [<ffffffffc045fe30>] btrfs_ioctl+0x550/0x28c0 [btrfs] kernel: [<ffffffff8120f84b>] ? mem_cgroup_try_charge+0x6b/0x1e0 kernel: [<ffffffff811a9ba7>] ? lru_cache_add_active_or_unevictable+0x27/0xa0 kernel: [<ffffffff811cc2ed>] ? handle_mm_fault+0xecd/0x1b80 kernel: [<ffffffff8123016f>] do_vfs_ioctl+0x2af/0x4b0 kernel: [<ffffffff8106dd51>] ? __do_page_fault+0x1c1/0x410 kernel: [<ffffffff812303e9>] SyS_ioctl+0x79/0x90 kernel: [<ffffffff81862a1b>] entry_SYSCALL_64_fastpath+0x22/0xcb kernel: INFO: task btrfs:2918 blocked for more than 120 seconds. kernel: Not tainted 4.4.0-146-generic #172-Ubuntu kernel: "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. kernel: btrfs D ffff88030bd07a98 0 2918 2892 0x00000000 kernel: ffff88030bd07a98 ffffffff81197240 ffffffff81e13500 ffff88033fe44e00 kernel: ffff88030bd08000 ffff88035dc88714 ffff88033fe44e00 00000000ffffffff kernel: ffff88035dc88718 ffff88030bd07ab0 ffffffff8185e0b5 ffff88035dc88710 kernel: Call Trace: kernel: [<ffffffff81197240>] ? printk+0x5a/0x76 kernel: [<ffffffff8185e0b5>] schedule+0x35/0x80 kernel: [<ffffffff8185e40e>] schedule_preempt_disabled+0xe/0x10 kernel: [<ffffffff818602a7>] __mutex_lock_slowpath+0xb7/0x130 kernel: [<ffffffff8186033f>] mutex_lock+0x1f/0x30 kernel: [<ffffffffc047b01b>] btrfs_relocate_block_group+0x1ab/0x290 [btrfs] kernel: [<ffffffffc044fe47>] btrfs_relocate_chunk.isra.39+0x47/0xd0 [btrfs] kernel: [<ffffffffc04512fa>] __btrfs_balance+0x5ba/0xb90 [btrfs] kernel: [<ffffffffc0451b60>] btrfs_balance+0x290/0x5f0 [btrfs] kernel: [<ffffffffc045d031>] btrfs_ioctl_balance+0x381/0x390 [btrfs] kernel: [<ffffffffc045fe30>] btrfs_ioctl+0x550/0x28c0 [btrfs] kernel: [<ffffffff8120f84b>] ? mem_cgroup_try_charge+0x6b/0x1e0 kernel: [<ffffffff811a9ba7>] ? lru_cache_add_active_or_unevictable+0x27/0xa0 kernel: [<ffffffff811cc2ed>] ? handle_mm_fault+0xecd/0x1b80 kernel: [<ffffffff8123016f>] do_vfs_ioctl+0x2af/0x4b0 kernel: [<ffffffff8106dd51>] ? __do_page_fault+0x1c1/0x410 kernel: [<ffffffff812303e9>] SyS_ioctl+0x79/0x90 kernel: [<ffffffff81862a1b>] entry_SYSCALL_64_fastpath+0x22/0xcb kernel: INFO: task btrfs:2918 blocked for more than 120 seconds. kernel: Not tainted 4.4.0-146-generic #172-Ubuntu kernel: "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. kernel: btrfs D ffff88030bd07a98 0 2918 2892 0x00000000 kernel: ffff88030bd07a98 ffffffff81197240 ffffffff81e13500 ffff88033fe44e00 kernel: ffff88030bd08000 ffff88035dc88714 ffff88033fe44e00 00000000ffffffff kernel: ffff88035dc88718 ffff88030bd07ab0 ffffffff8185e0b5 ffff88035dc88710 kernel: Call Trace: kernel: [<ffffffff81197240>] ? printk+0x5a/0x76 kernel: [<ffffffff8185e0b5>] schedule+0x35/0x80 kernel: [<ffffffff8185e40e>] schedule_preempt_disabled+0xe/0x10 kernel: [<ffffffff818602a7>] __mutex_lock_slowpath+0xb7/0x130 kernel: [<ffffffff8186033f>] mutex_lock+0x1f/0x30 kernel: [<ffffffffc047b01b>] btrfs_relocate_block_group+0x1ab/0x290 [btrfs] kernel: [<ffffffffc044fe47>] btrfs_relocate_chunk.isra.39+0x47/0xd0 [btrfs] kernel: [<ffffffffc04512fa>] __btrfs_balance+0x5ba/0xb90 [btrfs] kernel: [<ffffffffc0451b60>] btrfs_balance+0x290/0x5f0 [btrfs] kernel: [<ffffffffc045d031>] btrfs_ioctl_balance+0x381/0x390 [btrfs] kernel: [<ffffffffc045fe30>] btrfs_ioctl+0x550/0x28c0 [btrfs] kernel: [<ffffffff8120f84b>] ? mem_cgroup_try_charge+0x6b/0x1e0 kernel: [<ffffffff811a9ba7>] ? lru_cache_add_active_or_unevictable+0x27/0xa0 kernel: [<ffffffff811cc2ed>] ? handle_mm_fault+0xecd/0x1b80 kernel: [<ffffffff8123016f>] do_vfs_ioctl+0x2af/0x4b0 kernel: [<ffffffff8106dd51>] ? __do_page_fault+0x1c1/0x410 kernel: [<ffffffff812303e9>] SyS_ioctl+0x79/0x90 kernel: [<ffffffff81862a1b>] entry_SYSCALL_64_fastpath+0x22/0xcb
