From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Wheeler Subject: Re: bcache_writebac gets stuck on DRBD Date: Thu, 14 Jul 2016 14:29:01 -0700 (PDT) Message-ID: References: <5786A606.8030106@profihost.ag> <5787D021.3030305@profihost.ag> Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Return-path: Received: from mx.ewheeler.net ([66.155.3.69]:60263 "EHLO mail.ewheeler.net" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751247AbcGNV3F (ORCPT ); Thu, 14 Jul 2016 17:29:05 -0400 In-Reply-To: <5787D021.3030305@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 Thu, 14 Jul 2016, Stefan Priebe - Profihost AG wrote: > Am 13.07.2016 um 23:18 schrieb Eric Wheeler: > > 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 > > Yes that it makes it really complicated to know which patches to apply > to 4.4. Do you have any patches other than those above that should be included in the list for v4.3+ stability? -- Eric Wheeler > > Greets, > Stefan > > > > > > > -- > > 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 > >>> > >> > -- > 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 >