From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Wheeler Subject: Re: bcache_writebac gets stuck on DRBD Date: Wed, 13 Jul 2016 14:18:02 -0700 (PDT) Message-ID: References: <5786A606.8030106@profihost.ag> Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Return-path: Received: from mx.ewheeler.net ([66.155.3.69]:51304 "EHLO mail.ewheeler.net" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751053AbcGMVSE (ORCPT ); Wed, 13 Jul 2016 17:18:04 -0400 In-Reply-To: <5786A606.8030106@profihost.ag> Sender: linux-bcache-owner@vger.kernel.org List-Id: linux-bcache@vger.kernel.org To: Stefan Priebe - Profihost AG Cc: Jackie Tea , linux-bcache@vger.kernel.org On Wed, 13 Jul 2016, Stefan Priebe - Profihost AG wrote: > > Am 13.07.2016 um 08:18 schrieb Eric Wheeler: > > On Mon, 11 Jul 2016, Eric Wheeler wrote: > > > >> On Tue, 5 Jul 2016, Jackie Tea wrote: > >> > >>> I've been using bcache on a Xen host (sitting on an LVM partition) for > >>> many months without problems > >>> > >>> Now that I added DRBD on top of bcache, bcache locks up within a few > >>> hours, giving me this message: > >> > >> This might be related to the thread to this thread: > >> > >> https://lkml.org/lkml/2016/6/22/172 > >> and this patch: > >> https://patchwork.kernel.org/patch/9223697/ > >> > >> Notably, this bug was introduced in 4.3 and newer. You might try 4.1 and > >> see if your problem resolves itself, or 4.8 is supposed to fix this too if > >> the patch gets in. > > > > Make sure you have these patches, too. Looking at your stack, you > > definitely want "A", maybe the others as well: > > > > 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/ > > > > D. dm-crypt: Fix error with too large bios > > by Mikulas Patocka: https://patchwork.kernel.org/patch/9138595/ > > > > E. block: fix blk_queue_split() resource exhaustion > > by Lars Ellenberg: https://patchwork.kernel.org/patch/9223697/ > > (as above, previous post. > > > > Just want to let you now that here is stated that this does not always > fix C also a backport to 4.4 and others is currently missing: > https://bugzilla.kernel.org/show_bug.cgi?id=119841 Interesting, so Mikulas' "C" with threading/timer is fixing things that Lars' "E" did not? Well, here's hoping for a good fix. There are a lot of great developers working on this. More detail here: https://www.redhat.com/archives/dm-devel/2016-June/msg00425.html -- Eric Wheeler > > Stefan > > > You probably don't need "D" for your setup by looking at lsblk. > > > > [ "C" excluded on purpose because "E" supersedes it, but here it is if > > you'd like to try. Note that "E" and "C" are mutually exclusive: > > > > 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/) > > ] > > > > Please try and let us know which (if any of these) fix your issue! > > > > -Eric > > > > > > > > -- > > Eric Wheeler > > > > > >> > >> > >> > >>> > >>> Jul 5 04:06:43 dom0 kernel: [23043.136864] INFO: task > >>> bcache_writebac:1342 blocked for more than 120 seconds. > >>> Jul 5 04:06:43 dom0 kernel: [23043.136896] Not tainted > >>> 4.4.0-28-generic #47-Ubuntu > >>> Jul 5 04:06:43 dom0 kernel: [23043.136916] "echo 0 > > >>> /proc/sys/kernel/hung_task_timeout_secs" disables this message. > >>> Jul 5 04:06:43 dom0 kernel: [23043.136946] bcache_writebac D > >>> ffff880000983d18 0 1342 2 0x00000000 > >>> Jul 5 04:06:43 dom0 kernel: [23043.136952] ffff880000983d18 > >>> 0000000000007ff0 ffffffff81e11500 ffff880035705780 > >>> Jul 5 04:06:43 dom0 kernel: [23043.136955] ffff880000984000 > >>> ffff880005080af0 ffff880005080ad8 ffffffff00000000 > >>> Jul 5 04:06:43 dom0 kernel: [23043.136958] ffffffff00000003 > >>> ffff880000983d30 ffffffff818235b5 ffff880035705780 > >>> Jul 5 04:06:43 dom0 kernel: [23043.136962] Call Trace: > >>> Jul 5 04:06:43 dom0 kernel: [23043.136971] [] > >>> schedule+0x35/0x80 > >>> Jul 5 04:06:43 dom0 kernel: [23043.136974] [] > >>> rwsem_down_write_failed+0x202/0x350 > >>> Jul 5 04:06:43 dom0 kernel: [23043.136990] [] ? > >>> read_dirty+0x370/0x370 [bcache] > >>> Jul 5 04:06:43 dom0 kernel: [23043.136995] [] > >>> call_rwsem_down_write_failed+0x13/0x20 > >>> Jul 5 04:06:43 dom0 kernel: [23043.136999] [] ? > >>> down_write+0x2d/0x40 > >>> Jul 5 04:06:43 dom0 kernel: [23043.137009] [] > >>> bch_writeback_thread+0x5b/0x4c0 [bcache] > >>> Jul 5 04:06:43 dom0 kernel: [23043.137020] [] ? > >>> read_dirty+0x370/0x370 [bcache] > >>> Jul 5 04:06:43 dom0 kernel: [23043.137024] [] > >>> kthread+0xd8/0xf0 > >>> Jul 5 04:06:43 dom0 kernel: [23043.137027] [] ? > >>> kthread_create_on_node+0x1e0/0x1e0 > >>> Jul 5 04:06:43 dom0 kernel: [23043.137029] [] > >>> ret_from_fork+0x3f/0x70 > >>> Jul 5 04:06:43 dom0 kernel: [23043.137032] [] ? > >>> kthread_create_on_node+0x1e0/0x1e0 > >>> Jul 5 04:06:43 dom0 kernel: [23043.137043] INFO: task > >>> blkback.5.hda:3357 blocked for more than 120 seconds. > >>> Jul 5 04:06:43 dom0 kernel: [23043.137069] Not tainted > >>> 4.4.0-28-generic #47-Ubuntu > >>> Jul 5 04:06:43 dom0 kernel: [23043.137090] "echo 0 > > >>> /proc/sys/kernel/hung_task_timeout_secs" disables this message. > >>> Jul 5 04:06:43 dom0 kernel: [23043.137119] blkback.5.hda D > >>> ffff88002341ba48 0 3357 2 0x00000000 > >>> Jul 5 04:06:43 dom0 kernel: [23043.137122] ffff88002341ba48 > >>> ffff88002341ba08 ffffffff81e11500 ffff880034189900 > >>> Jul 5 04:06:43 dom0 kernel: [23043.137124] ffff88002341c000 > >>> ffff880005080ad8 ffff880005080af0 ffff880023e08e60 > >>> Jul 5 04:06:43 dom0 kernel: [23043.137126] ffff880005080000 > >>> ffff88002341ba60 ffffffff818235b5 ffff880034189900 > >>> Jul 5 04:06:43 dom0 kernel: [23043.137128] Call Trace: > >>> Jul 5 04:06:43 dom0 kernel: [23043.137131] [] > >>> schedule+0x35/0x80 > >>> Jul 5 04:06:43 dom0 kernel: [23043.137133] [] > >>> rwsem_down_read_failed+0xe0/0x140 > >>> Jul 5 04:06:43 dom0 kernel: [23043.137136] [] ? > >>> mempool_alloc_slab+0x15/0x20 > >>> Jul 5 04:06:43 dom0 kernel: [23043.137138] [] > >>> call_rwsem_down_read_failed+0x14/0x30 > >>> Jul 5 04:06:43 dom0 kernel: [23043.137140] [] ? > >>> down_read+0x20/0x30 > >>> Jul 5 04:06:43 dom0 kernel: [23043.137148] [] > >>> cached_dev_make_request+0x682/0xcc0 [bcache] > >>> Jul 5 04:06:43 dom0 kernel: [23043.137151] [] > >>> generic_make_request+0xf2/0x1d0 > >>> Jul 5 04:06:43 dom0 kernel: [23043.137153] [] > >>> submit_bio+0x76/0x170 > >>> Jul 5 04:06:43 dom0 kernel: [23043.137157] [] > >>> dispatch_rw_block_io+0x7b7/0xab0 [xen_blkback] > >>> Jul 5 04:06:43 dom0 kernel: [23043.137159] [] ? > >>> xen_load_sp0+0x84/0x180 > >>> Jul 5 04:06:43 dom0 kernel: [23043.137162] [] ? > >>> __raw_callee_save___pv_queued_spin_unlock+0x11/0x20 > >>> Jul 5 04:06:43 dom0 kernel: [23043.137165] [] > >>> __do_block_io_op+0x395/0x710 [xen_blkback] > >>> Jul 5 04:06:43 dom0 kernel: [23043.137167] [] ? > >>> del_timer_sync+0x48/0x50 > >>> Jul 5 04:06:43 dom0 kernel: [23043.137170] [] > >>> xen_blkif_schedule+0xdd/0x7b0 [xen_blkback] > >>> Jul 5 04:06:43 dom0 kernel: [23043.137172] [] ? > >>> finish_task_switch+0x7d/0x220 > >>> Jul 5 04:06:43 dom0 kernel: [23043.137175] [] ? > >>> wake_atomic_t_function+0x60/0x60 > >>> Jul 5 04:06:43 dom0 kernel: [23043.137177] [] ? > >>> xen_blkif_be_int+0x30/0x30 [xen_blkback] > >>> Jul 5 04:06:43 dom0 kernel: [23043.137179] [] > >>> kthread+0xd8/0xf0 > >>> Jul 5 04:06:43 dom0 kernel: [23043.137181] [] ? > >>> kthread_create_on_node+0x1e0/0x1e0 > >>> Jul 5 04:06:43 dom0 kernel: [23043.137183] [] > >>> ret_from_fork+0x3f/0x70 > >>> Jul 5 04:06:43 dom0 kernel: [23043.137185] [] ? > >>> kthread_create_on_node+0x1e0/0x1e0 > >>> > >>> At the same time (but always after bcache), Xen's blkback will also > >>> give a similar message: > >>> > >>> Jul 5 04:08:43 dom0 kernel: [23163.135027] INFO: task > >>> bcache_writebac:1342 blocked for more than 120 seconds. > >>> Jul 5 04:08:43 dom0 kernel: [23163.135056] Not tainted > >>> 4.4.0-28-generic #47-Ubuntu > >>> Jul 5 04:08:43 dom0 kernel: [23163.135076] "echo 0 > > >>> /proc/sys/kernel/hung_task_timeout_secs" disables this message. > >>> Jul 5 04:08:43 dom0 kernel: [23163.135105] bcache_writebac D > >>> ffff880000983d18 0 1342 2 0x00000000 > >>> Jul 5 04:08:43 dom0 kernel: [23163.135109] ffff880000983d18 > >>> 0000000000007ff0 ffffffff81e11500 ffff880035705780 > >>> Jul 5 04:08:43 dom0 kernel: [23163.135112] ffff880000984000 > >>> ffff880005080af0 ffff880005080ad8 ffffffff00000000 > >>> Jul 5 04:08:43 dom0 kernel: [23163.135114] ffffffff00000003 > >>> ffff880000983d30 ffffffff818235b5 ffff880035705780 > >>> Jul 5 04:08:43 dom0 kernel: [23163.135116] Call Trace: > >>> Jul 5 04:08:43 dom0 kernel: [23163.135124] [] > >>> schedule+0x35/0x80 > >>> Jul 5 04:08:43 dom0 kernel: [23163.135127] [] > >>> rwsem_down_write_failed+0x202/0x350 > >>> Jul 5 04:08:43 dom0 kernel: [23163.135139] [] ? > >>> read_dirty+0x370/0x370 [bcache] > >>> Jul 5 04:08:43 dom0 kernel: [23163.135143] [] > >>> call_rwsem_down_write_failed+0x13/0x20 > >>> Jul 5 04:08:43 dom0 kernel: [23163.135145] [] ? > >>> down_write+0x2d/0x40 > >>> Jul 5 04:08:43 dom0 kernel: [23163.135153] [] > >>> bch_writeback_thread+0x5b/0x4c0 [bcache] > >>> Jul 5 04:08:43 dom0 kernel: [23163.135160] [] ? > >>> read_dirty+0x370/0x370 [bcache] > >>> Jul 5 04:08:43 dom0 kernel: [23163.135162] [] > >>> kthread+0xd8/0xf0 > >>> Jul 5 04:08:43 dom0 kernel: [23163.135164] [] ? > >>> kthread_create_on_node+0x1e0/0x1e0 > >>> Jul 5 04:08:43 dom0 kernel: [23163.135166] [] > >>> ret_from_fork+0x3f/0x70 > >>> Jul 5 04:08:43 dom0 kernel: [23163.135168] [] ? > >>> kthread_create_on_node+0x1e0/0x1e0 > >>> Jul 5 04:08:43 dom0 kernel: [23163.135178] INFO: task > >>> blkback.5.hda:3357 blocked for more than 120 seconds. > >>> Jul 5 04:08:43 dom0 kernel: [23163.135204] Not tainted > >>> 4.4.0-28-generic #47-Ubuntu > >>> Jul 5 04:08:43 dom0 kernel: [23163.135224] "echo 0 > > >>> /proc/sys/kernel/hung_task_timeout_secs" disables this message. > >>> Jul 5 04:08:43 dom0 kernel: [23163.135286] blkback.5.hda D > >>> ffff88002341ba48 0 3357 2 0x00000000 > >>> Jul 5 04:08:43 dom0 kernel: [23163.135289] ffff88002341ba48 > >>> ffff88002341ba08 ffffffff81e11500 ffff880034189900 > >>> Jul 5 04:08:43 dom0 kernel: [23163.135291] ffff88002341c000 > >>> ffff880005080ad8 ffff880005080af0 ffff880023e08e60 > >>> Jul 5 04:08:43 dom0 kernel: [23163.135293] ffff880005080000 > >>> ffff88002341ba60 ffffffff818235b5 ffff880034189900 > >>> Jul 5 04:08:43 dom0 kernel: [23163.135295] Call Trace: > >>> Jul 5 04:08:43 dom0 kernel: [23163.135299] [] > >>> schedule+0x35/0x80 > >>> Jul 5 04:08:43 dom0 kernel: [23163.135301] [] > >>> rwsem_down_read_failed+0xe0/0x140 > >>> Jul 5 04:08:43 dom0 kernel: [23163.135304] [] ? > >>> mempool_alloc_slab+0x15/0x20 > >>> Jul 5 04:08:43 dom0 kernel: [23163.135307] [] > >>> call_rwsem_down_read_failed+0x14/0x30 > >>> Jul 5 04:08:43 dom0 kernel: [23163.135309] [] ? > >>> down_read+0x20/0x30 > >>> Jul 5 04:08:43 dom0 kernel: [23163.135316] [] > >>> cached_dev_make_request+0x682/0xcc0 [bcache] > >>> Jul 5 04:08:43 dom0 kernel: [23163.135319] [] > >>> generic_make_request+0xf2/0x1d0 > >>> Jul 5 04:08:43 dom0 kernel: [23163.135321] [] > >>> submit_bio+0x76/0x170 > >>> Jul 5 04:08:43 dom0 kernel: [23163.135326] [] > >>> dispatch_rw_block_io+0x7b7/0xab0 [xen_blkback] > >>> Jul 5 04:08:43 dom0 kernel: [23163.135328] [] ? > >>> xen_load_sp0+0x84/0x180 > >>> Jul 5 04:08:43 dom0 kernel: [23163.135331] [] ? > >>> __raw_callee_save___pv_queued_spin_unlock+0x11/0x20 > >>> Jul 5 04:08:43 dom0 kernel: [23163.135334] [] > >>> __do_block_io_op+0x395/0x710 [xen_blkback] > >>> Jul 5 04:08:43 dom0 kernel: [23163.135337] [] ? > >>> del_timer_sync+0x48/0x50 > >>> Jul 5 04:08:43 dom0 kernel: [23163.135340] [] > >>> xen_blkif_schedule+0xdd/0x7b0 [xen_blkback] > >>> Jul 5 04:08:43 dom0 kernel: [23163.135343] [] ? > >>> finish_task_switch+0x7d/0x220 > >>> Jul 5 04:08:43 dom0 kernel: [23163.135346] [] ? > >>> wake_atomic_t_function+0x60/0x60 > >>> Jul 5 04:08:43 dom0 kernel: [23163.135348] [] ? > >>> xen_blkif_be_int+0x30/0x30 [xen_blkback] > >>> Jul 5 04:08:43 dom0 kernel: [23163.135350] [] > >>> kthread+0xd8/0xf0 > >>> Jul 5 04:08:43 dom0 kernel: [23163.135352] [] ? > >>> kthread_create_on_node+0x1e0/0x1e0 > >>> Jul 5 04:08:43 dom0 kernel: [23163.135354] [] > >>> ret_from_fork+0x3f/0x70 > >>> Jul 5 04:08:43 dom0 kernel: [23163.135356] [] ? > >>> kthread_create_on_node+0x1e0/0x1e0 > >>> > >>> Access to the storage is no longer possible, then (it'll just appear to hang). > >>> This is on the newest Ubuntu 16.04 LTS, with their 4.4.0-28 kernel. > >>> > >>> # lsb_release -d > >>> Description: Ubuntu 16.04 LTS > >>> # uname -r > >>> 4.4.0-28-generic > >>> > >>> bcache is set to writeback. > >>> > >>> # cat /sys/block/bcache0/bcache/cache_mode > >>> writethrough [writeback] writearound none > >>> # cat /sys/block/bcache0/bcache/state > >>> dirty > >>> # cat /sys/block/bcache0/bcache/dirty_data > >>> 56.0k > >>> > >>> The relevant disk stack looks like this: > >>> > >>> # lsblk > >>> sdd 8:48 0 232.9G 0 disk > >>> `-sdd1 8:49 0 232.9G 0 part > >>> `-md1 9:1 0 232.8G 0 raid1 > >>> `-ssd-bcache--back 252:4 0 30G 0 lvm > >>> `-bcache0 251:0 0 2T 0 disk > >>> `-storage-drback--test 252:6 0 200G 0 lvm > >>> > >>> storage-drback--test is the backing device for DRBD. > >>> > >>> This is reproducible, but I do not know what causes it, or how to > >>> cause it on purpose. All I know is that once I put DRBD on top of > >>> bcache, and produce minor load over time (I just have a single idle > >>> Windows 2012R2 server on it as test - as Windows would always do > >>> *something* ;-) it will lock up within 8 hours. > >>> > >>> Do you have any clues as to what could be causing this? > >>> -- > >>> To unsubscribe from this list: send the line "unsubscribe linux-bcache" in > >>> the body of a message to majordomo@vger.kernel.org > >>> 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@vger.kernel.org > >> 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@vger.kernel.org > > More majordomo info at http://vger.kernel.org/majordomo-info.html > > >