On Fri, 16 Sep 2016, Matthias Ferdinand wrote: > [sorry if you get this twice - I haven't seen this message appear on the > list] > > On Tue, Jul 12, 2016 at 07:18:58PM -0700, Eric Wheeler wrote: > > since 4.3 related to bio splitting/large bios? I've been collecting a > > list, none of which appear have landed yet as of 4.7-rc7 (but correct me > > if I'm wrong): > > > > A. [PATCH v2] block: make sure big bio is splitted into at most 256 bvecs > > by Ming Lei: https://patchwork.kernel.org/patch/9169483/ > > > > B. block: don't make BLK_DEF_MAX_SECTORS too big > > by Shaohua Li: http://www.spinics.net/lists/linux-bcache/msg03525.html > > > > C. [1/3] block: flush queued bios when process blocks to avoid deadlock > > by Mikulas Patocka: https://patchwork.kernel.org/patch/9204125/ > > (was https://patchwork.kernel.org/patch/7398411/) > > > > D. dm-crypt: Fix error with too large bios > > by Mikulas Patocka: https://patchwork.kernel.org/patch/9138595/ > > > Hi, > > trying to run some qemu-kvm benchmarks over LVM+bcache+mdraid5(4 disks), What is your SSD stack for the bcache cachedev? > on Ubuntu 14.04 x86_64 with various kernels. > Especially with VMs on writeable snapshots, I either get > "bcache_writeback blocked" or "kernel BUG" rather quickly, even with > most recent 4.8.0 kernel. In my benchmark setup, I use 4 VMs each > running on a writeable snapshot from the same (not written to) base LV. > They are Ubuntu 12.04 images doing dist-upgrade including > Kernel-Updates. They also do quite a bit of swapping, as they have only > 208MB RAM. > > Other (non-KVM) benchmarks directly on /dev/bcache0 ran for more than a > week (kernel 4.4.0) before eventually producing a "blocked for more than > 120 seconds" message and stalling I/O on it. > > > Tried patches A, B, C, E, but only E does still apply to 4.8 (with some > hand-work). > > Any other patches I should try? > > > Regards > Matthias > > ----------------------------------------------------------------------- > > unmodified 4.8.0-rc6: after some time, I/O completely stops: > > [ 1571.880480] INFO: task bcache_writebac:5469 blocked for more than 120 seconds. > [ 1571.916217] Not tainted 4.8.0-rc6 #1 > [ 1571.934039] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. > [ 1571.971060] INFO: task qemu-system-x86:6499 blocked for more than 120 seconds. > [ 1572.009144] Not tainted 4.8.0-rc6 #1 > [ 1572.028125] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. Please cat /proc/pid/stack for each hanging pid. I wonder, just where are those tasks stuck? > 4.8.0-rc5 + LGE's patch (E, > v2-1-1-block-fix-blk_queue_split-resource-exhaustion.patch from > https://patchwork.kernel.org/patch/9223697/ ): > runs longer than without that patch, but sometimes runs into a > BUG_ON. By calling "lvremove", I can reliably provoke that BUG. > > [ 1930.459062] kernel BUG at block/bio.c:1789! > [ 1930.459648] invalid opcode: 0000 [#1] SMP > [ 1930.460208] Modules linked in: dm_snapshot dm_bufio bcache ipt_MASQUERADE nf_nat_masquerade_ipv4 iptable_nat nf_nat_ipv4 nf_nat nf_conntrack_ipv4 nf_defrag_ipv4 xt_conntrack nf_conntrack ipt_REJECT nf_reject_ipv4 xt_CHECKSUM iptable_mangle xt_tcpudp bridge stp llc ip6table_filter ip6_tables iptable_filter ip_tables ebtable_nat ebtables x_tables intel_rapl x86_pkg_temp_thermal intel_powerclamp coretemp gpio_ich ipmi_ssif kvm_intel kvm irqbypass crct10dif_pclmul crc32_pclmul ghash_clmulni_intel cryptd dm_multipath serio_raw ipmi_si input_leds ie31200_edac ipmi_msghandler acpi_power_meter lp hpilo edac_core lpc_ich parport btrfs raid10 raid456 async_raid6_recov async_memcpy async_pq async_xor async_tx xor uas usb_storage hid_generic raid6_pq libcrc32c usbhid hid raid1 tg3 raid0 ptp pps_core psmouse ahci libahci multipath linear [last unloaded: bcache] > [ 1930.520004] CPU: 0 PID: 12673 Comm: lvremove Not tainted 4.8.0-rc5 #2 > [ 1930.545645] Hardware name: HP ProLiant MicroServer Gen8, BIOS J06 07/16/2015 > [ 1930.571245] task: ffff8ce733702580 task.stack: ffff8ce727900000 > [ 1930.596750] RIP: 0010:[<ffffffff96386e2a>] [<ffffffff96386e2a>] bio_split+0x8a/0x90 > [ 1930.647161] RSP: 0018:ffff8ce727903b78 EFLAGS: 00010246 > [ 1930.672259] RAX: 00000000000000a8 RBX: 000000000001f000 RCX: ffff8ce724974d00 > [ 1930.697289] RDX: 0000000002400000 RSI: 0000000000000000 RDI: ffff8ce7296ef120 > [ 1930.722309] RBP: ffff8ce727903b90 R08: 0000000000000000 R09: ffff8ce7296ef120 > [ 1930.746862] R10: 00058000ffffffff R11: 0000000000000000 R12: 0000000000000000 > [ 1930.771080] R13: 0000000000000000 R14: 0000000000000000 R15: 00000000000000a8 > [ 1930.794656] FS: 00007fd3c64d5840(0000) GS:ffff8ce73a200000(0000) knlGS:0000000000000000 > [ 1930.840550] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > [ 1930.863312] CR2: 00007f8e88bb2000 CR3: 00000002e16f8000 CR4: 00000000001406f0 > [ 1930.886799] Stack: > [ 1930.909851] 000000000001f000 0000000000000000 0000000000000000 ffff8ce727903c30 > [ 1930.957581] ffffffff96393aad ffff8ce7281eb890 ffff8ce727903bf0 ffff8ce724974d00 > [ 1931.006067] 0000000000000000 ffff8ce725b62c60 ffff8ce727903c40 00000058281eb890 > [ 1931.054370] Call Trace: > [ 1931.077608] [<ffffffff96393aad>] blk_queue_split+0x47d/0x640 > [ 1931.101157] [<ffffffff9638f3a4>] blk_queue_bio+0x44/0x390 > [ 1931.124083] [<ffffffff9638d8c4>] generic_make_request+0x104/0x1b0 > [ 1931.146371] [<ffffffff9638d9dd>] submit_bio+0x6d/0x150 > [ 1931.168393] [<ffffffff96385649>] ? bio_alloc_bioset+0x169/0x2b0 > [ 1931.189853] [<ffffffff96395e68>] next_bio+0x38/0x40 > [ 1931.210743] [<ffffffff96395f93>] __blkdev_issue_discard+0x123/0x1c0 > [ 1931.231522] [<ffffffff963961c2>] blkdev_issue_discard+0x52/0xa0 > [ 1931.251942] [<ffffffff9639c360>] blk_ioctl_discard+0x80/0xa0 Looks discard related. If you get a good way to reproduce reliabily, then please report a new BUG thread and Cc linux-block. Try turning off discard and see if the issue goes away. > [ 1931.272067] [<ffffffff9639cfb6>] blkdev_ioctl+0x716/0x8c0 > [ 1931.291454] [<ffffffff9621db04>] ? mntput+0x24/0x40 > [ 1931.310551] [<ffffffff96237231>] block_ioctl+0x41/0x50 > [ 1931.329247] [<ffffffff96210676>] do_vfs_ioctl+0x96/0x5a0 > [ 1931.347634] [<ffffffff961bb7d8>] ? do_munmap+0x298/0x390 > [ 1931.366132] [<ffffffff96210bf9>] SyS_ioctl+0x79/0x90 > [ 1931.384667] [<ffffffff967b49b6>] entry_SYSCALL_64_fastpath+0x1e/0xa8 > > > > 4.4.0 (Ubuntu backport kernel from Ubuntu 16.04 "xenial"): > [ 960.092547] INFO: task bcache_writebac:5260 blocked for more than 120 seconds. > [ 960.093584] Not tainted 4.4.0-31-generic #50~14.04.1 > [ 960.094377] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. > [ 960.095553] INFO: task qemu-system-x86:6179 blocked for more than 120 seconds. > [ 960.096593] Not tainted 4.4.0-31-generic #50~14.04.1 > [ 960.097364] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. > > > 4.2.0 (Ubuntu backport kernel from Ubuntu 15.10 "wily") There was a lot of churn from v4.2 to v4.3 in the block layer. Please test with v4.1.31 or newer. If you find a working version, then a bisect would be useful. -- Eric Wheeler > > [ 4557.761416] INFO: task bcache_writebac:11995 blocked for more than 120 seconds. > [ 4557.762454] Not tainted 4.2.0-36-generic #41~14.04.1-Ubuntu > [ 4557.763309] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. > [ 4557.764413] bcache_writebac D 0000000000000000 0 11995 2 0x00000000 > [ 4557.764418] ffff8803e901bd08 0000000000000046 ffff8803f5992640 ffff8803f5994c80 > [ 4557.764420] ffff8803e901bd28 ffff8803e901c000 ffff8800a7e80b00 ffff8800a7e80ae8 > [ 4557.764422] ffffffff00000000 ffffffff00000003 ffff8803e901bd28 ffffffff817bfca7 > [ 4557.764425] Call Trace: > [ 4557.764433] [<ffffffff817bfca7>] schedule+0x37/0x80 > [ 4557.764435] [<ffffffff817c21b0>] rwsem_down_write_failed+0x1d0/0x320 > [ 4557.764447] [<ffffffffc04c45d3>] ? closure_sync+0x23/0x90 [bcache] > [ 4557.764452] [<ffffffff813b8f33>] call_rwsem_down_write_failed+0x13/0x20 > [ 4557.764454] [<ffffffff817c1a81>] ? down_write+0x31/0x50 > [ 4557.764463] [<ffffffffc04d960c>] bch_writeback_thread+0x4c/0x480 [bcache] > [ 4557.764470] [<ffffffffc04d95c0>] ? read_dirty+0x3f0/0x3f0 [bcache] > [ 4557.764473] [<ffffffff81097c62>] kthread+0xd2/0xf0 > [ 4557.764476] [<ffffffff81097b90>] ? kthread_create_on_node+0x1c0/0x1c0 > [ 4557.764478] [<ffffffff817c399f>] ret_from_fork+0x3f/0x70 > [ 4557.764480] [<ffffffff81097b90>] ? kthread_create_on_node+0x1c0/0x1c0 > [ 4557.764484] INFO: task kworker/0:17:13958 blocked for more than 120 seconds. > [ 4557.765494] Not tainted 4.2.0-36-generic #41~14.04.1-Ubuntu > [ 4557.766363] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. > [ 4557.767467] kworker/0:17 D ffff8803fa216640 0 13958 2 0x00000000 > [ 4557.767476] Workqueue: events update_writeback_rate [bcache] > [ 4557.767477] ffff880324dfbcc0 0000000000000046 ffffffff81c14500 ffff8800a894bfc0 > [ 4557.767479] ffffffff810e3678 ffff880324dfc000 ffff8800a7e80ae8 ffff8800a7e80b00 > [ 4557.767482] 0000000000000000 ffff8800a7e80b28 ffff880324dfbce0 ffffffff817bfca7 > [ 4557.767484] Call Trace: > [ 4557.767487] [<ffffffff810e3678>] ? add_timer_on+0xb8/0x120 > [ 4557.767490] [<ffffffff817bfca7>] schedule+0x37/0x80 > [ 4557.767492] [<ffffffff817c23e0>] rwsem_down_read_failed+0xe0/0x120 > [ 4557.767495] [<ffffffff81090270>] ? try_to_grab_pending+0xb0/0x150 > [ 4557.767498] [<ffffffff813b8f04>] call_rwsem_down_read_failed+0x14/0x30 > [ 4557.767500] [<ffffffff817c1a44>] ? down_read+0x24/0x30 > [ 4557.767506] [<ffffffffc04d8b05>] update_writeback_rate+0x25/0x210 [bcache] > [ 4557.767509] [<ffffffff81091f1d>] process_one_work+0x14d/0x3f0 > [ 4557.767512] [<ffffffff8109269a>] worker_thread+0x11a/0x470 > [ 4557.767514] [<ffffffff81092580>] ? rescuer_thread+0x310/0x310 > [ 4557.767516] [<ffffffff81097c62>] kthread+0xd2/0xf0 > [ 4557.767519] [<ffffffff81097b90>] ? kthread_create_on_node+0x1c0/0x1c0 > [ 4557.767521] [<ffffffff817c399f>] ret_from_fork+0x3f/0x70 > [ 4557.767523] [<ffffffff81097b90>] ? kthread_create_on_node+0x1c0/0x1c0 > -- > To unsubscribe from this list: send the line "unsubscribe linux-bcache" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html > -- To unsubscribe from this list: send the line "unsubscribe linux-bcache" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
