Hi, This happens systematically these days, while trying to backup using rsync two of my laptops on an external HD - BTRFS formatted. First at mount : juil. 19 09:08:32 zafu kernel: BTRFS info (device dm-3): disk space caching is enabled juil. 19 09:08:38 zafu kernel: pool[7215]: segfault at 58252fd0 ip 00007fd06e466ac7 sp 00007fd062ffbf90 error 4 in libc-2.19.so[7fd06e41e000+1a4000] Happening on 2 different machines (both Arch Linux with latest kernel), I suspected the external HD, but it spent the night passing all long SMART tests plus a "btrfs scrub", all with flying colors... After the following error, all accesses to the external HD lock until a forced power off of the whole system... juil. 19 09:12:57 zafu kernel: INFO: task kworker/u4:7:6677 blocked for more than 120 seconds. juil. 19 09:12:57 zafu kernel: Tainted: G O 3.15.5-2-ARCH #1 juil. 19 09:12:57 zafu kernel: "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. juil. 19 09:12:57 zafu kernel: kworker/u4:7 D 0000000000000000 0 6677 2 0x00000000 juil. 19 09:12:57 zafu kernel: Workqueue: btrfs-flush_delalloc normal_work_helper [btrfs] juil. 19 09:12:57 zafu kernel: ffff88001e9dfb48 0000000000000046 ffff8800879f1460 0000000000014700 juil. 19 09:12:57 zafu kernel: ffff88001e9dffd8 0000000000014700 ffff8800879f1460 ffffffffa0262692 juil. 19 09:12:57 zafu kernel: 0000000000000000 ffffffff00000050 ffff88001e9dfbc4 ffff88001e9dfac8 juil. 19 09:12:57 zafu kernel: Call Trace: juil. 19 09:12:57 zafu kernel: [<ffffffffa0262692>] ? run_delalloc_range+0x192/0x350 [btrfs] juil. 19 09:12:57 zafu kernel: [<ffffffff8113f880>] ? filemap_fdatawait+0x30/0x30 juil. 19 09:12:57 zafu kernel: [<ffffffff81509fa9>] schedule+0x29/0x70 juil. 19 09:12:57 zafu kernel: [<ffffffff8150a294>] io_schedule+0x94/0xf0 juil. 19 09:12:57 zafu kernel: [<ffffffff8113f88e>] sleep_on_page+0xe/0x20 juil. 19 09:12:57 zafu kernel: [<ffffffff8150a788>] __wait_on_bit_lock+0x48/0xb0 juil. 19 09:12:57 zafu kernel: [<ffffffff8113f9e8>] __lock_page+0x78/0x90 juil. 19 09:12:57 zafu kernel: [<ffffffff810b1c80>] ? autoremove_wake_function+0x40/0x40 juil. 19 09:12:57 zafu kernel: [<ffffffffa027ac98>] extent_write_cache_pages.isra.28.constprop.45+0x258/0x3a0 [btrfs] juil. 19 09:12:57 zafu kernel: [<ffffffff810a714c>] ? update_curr+0xec/0x1b0 juil. 19 09:12:57 zafu kernel: [<ffffffff810a3068>] ? __enqueue_entity+0x78/0x80 juil. 19 09:12:57 zafu kernel: [<ffffffff810a902e>] ? enqueue_entity+0x24e/0xaa0 juil. 19 09:12:57 zafu kernel: [<ffffffffa027c20c>] extent_writepages+0x5c/0x90 [btrfs] juil. 19 09:12:57 zafu kernel: [<ffffffffa025e9d0>] ? __btrfs_submit_bio_start_direct_io+0x40/0x40 [btrfs] juil. 19 09:12:57 zafu kernel: [<ffffffffa025d6e8>] btrfs_writepages+0x28/0x30 [btrfs] juil. 19 09:12:57 zafu kernel: [<ffffffff8114d1de>] do_writepages+0x1e/0x30 juil. 19 09:12:57 zafu kernel: [<ffffffff8114139d>] __filemap_fdatawrite_range+0x5d/0x80 juil. 19 09:12:57 zafu kernel: [<ffffffff8114140c>] filemap_flush+0x1c/0x20 juil. 19 09:12:57 zafu kernel: [<ffffffffa026046a>] btrfs_run_delalloc_work+0x5a/0xa0 [btrfs] juil. 19 09:12:57 zafu kernel: [<ffffffffa028aa77>] normal_work_helper+0x77/0x350 [btrfs] juil. 19 09:12:57 zafu kernel: [<ffffffff810861d8>] process_one_work+0x168/0x450 juil. 19 09:12:57 zafu kernel: [<ffffffff81086c32>] worker_thread+0x132/0x3e0 juil. 19 09:12:57 zafu kernel: [<ffffffff81086b00>] ? manage_workers.isra.23+0x2d0/0x2d0 juil. 19 09:12:57 zafu kernel: [<ffffffff8108d43a>] kthread+0xea/0x100 juil. 19 09:12:57 zafu kernel: [<ffffffff8108d350>] ? kthread_create_on_node+0x1b0/0x1b0 juil. 19 09:12:57 zafu kernel: [<ffffffff81515efc>] ret_from_fork+0x7c/0xb0 juil. 19 09:12:57 zafu kernel: [<ffffffff8108d350>] ? kthread_create_on_node+0x1b0/0x1b0 -- Swâmi Petaramesh <swami@petaramesh.org> http://petaramesh.org PGP 9076E32E -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html