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Message-ID: <CAKbGBLjYWggnVeggj-d3-jTUqgFFwWyiih4VNM5yyuakd6yamg@mail.gmail.com> Date: Wed, 19 Feb 2014 13:01:41 -0800 From: Steven Noonan <steven@...inklabs.net> To: Konrad Rzeszutek Wilk <konrad.wilk@...cle.com> Cc: Linux Kernel Mailing List <linux-kernel@...r.kernel.org>, Mel Gorman <mgorman@...e.de>, Rik van Riel <riel@...hat.com>, Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...nel.org>, Andrea Arcangeli <aarcange@...hat.com>, Johannes Weiner <hannes@...xchg.org>, Srikar Dronamraju <srikar@...ux.vnet.ibm.com> Subject: Re: [BISECTED] Xen HVM guest hangs since 3.12-rc5 On Wed, Feb 19, 2014 at 9:41 AM, Konrad Rzeszutek Wilk <konrad.wilk@...cle.com> wrote: > On Tue, Feb 18, 2014 at 11:16:05PM -0800, Steven Noonan wrote: >> I've been running into problems on an Xen HVM domU. I've got a guest with NUMA >> enabled, 60GB of RAM, and 3 disks attached (including root volume). 2 of the >> disks are in an MD RAID0 in the guest, with an ext4 filesystem on top of that. >> I was running the fio 'iometer-file-access-server.fio' example config against >> that fs. During this workload, it would eventually cause a soft lockup, like >> the below: > > I presume since you mention NUMA and Mel is CC-ed that if you boot without > NUMA enabled (either via the toolstack or via Linux command line) - the issue > is not present? I mentioned NUMA because the bisected commit is sched/numa, and the guest is NUMA-enabled. I hadn't attempted booting with NUMA off. I just tried with numa=off, and the workload has run in a loop for 20 minutes so far with no issues (normally the issue would repro in less than 5). >> >> [ 2536.250054] BUG: soft lockup - CPU#0 stuck for 23s! [kworker/u257:0:7] >> [ 2536.250054] Modules linked in: isofs crct10dif_pclmul crct10dif_common crc32_pclmul crc32c_intel ghash_clmulni_intel aesni_intel aes_x86_64 lrw gf128mul glue_helper ablk_helper cryptd raid0 md_mod acpi_cpufreq psmouse i2c_piix4 intel_agp intel_gtt i2c_core processor serio_raw evdev microcode ext4 crc16 mbcache jbd2 ata_generic pata_acpi ata_piix libata scsi_mod floppy ixgbevf xen_privcmd xen_netfront xen_kbdfront syscopyarea sysfillrect sysimgblt fb_sys_fops xen_blkfront virtio_pci virtio_net virtio_blk virtio_ring virtio ipmi_poweroff ipmi_msghandler button >> [ 2536.250054] CPU: 0 PID: 7 Comm: kworker/u257:0 Tainted: G W 3.12.0-rc4-bisect-00073-g6fe6b2d #26 >> [ 2536.250054] Hardware name: Xen HVM domU, BIOS 4.2.amazon 01/14/2014 >> [ 2536.250054] Workqueue: writeback bdi_writeback_workfn (flush-202:0) >> [ 2536.250054] task: ffff880766533400 ti: ffff88076652e000 task.ti: ffff88076652e000 >> [ 2536.250054] RIP: 0010:[<ffffffff810cc518>] [<ffffffff810cc518>] smp_call_function_many+0x258/0x2b0 >> [ 2536.250054] RSP: 0018:ffff88076652f878 EFLAGS: 00000202 >> [ 2536.250054] RAX: 000000000000000f RBX: ffff88076652f808 RCX: ffff880ef0ef74a8 >> [ 2536.250054] RDX: 000000000000000f RSI: 0000000000000080 RDI: 0000000000000000 >> [ 2536.250054] RBP: ffff88076652f8c0 R08: ffff880771046c00 R09: ffff880770c008e0 >> [ 2536.250054] R10: 000000000000003e R11: 0000000000000210 R12: ffff88076652f7f0 >> [ 2536.250054] R13: ffffffff810b859e R14: ffff88076652f7e0 R15: ffffffff810b50e7 >> [ 2536.250054] FS: 0000000000000000(0000) GS:ffff880771600000(0000) knlGS:0000000000000000 >> [ 2536.250054] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 >> [ 2536.250054] CR2: 00007f8752bea000 CR3: 0000000001a0d000 CR4: 00000000001406f0 >> [ 2536.250054] Stack: >> [ 2536.250054] 0000000181275231 0000000000014d00 ffff88076652f8d0 ffffffff810564e0 >> [ 2536.250054] ffff88076530b180 00007f0c8826a000 ffff880ed4d57700 ffff88076530b180 >> [ 2536.250054] ffff880ed4cc6350 ffff88076652f8e8 ffffffff81056637 ffff88076530b180 >> [ 2536.250054] Call Trace: >> [ 2536.250054] [<ffffffff810564e0>] ? leave_mm+0x70/0x70 >> [ 2536.250054] [<ffffffff81056637>] native_flush_tlb_others+0x37/0x40 >> [ 2536.250054] [<ffffffff81056988>] flush_tlb_page+0x88/0x90 >> [ 2536.250054] [<ffffffff8117bb94>] ptep_clear_flush+0x34/0x40 >> [ 2536.250054] [<ffffffff81175b1e>] page_mkclean+0x12e/0x1d0 >> [ 2536.250054] [<ffffffff8114aeeb>] clear_page_dirty_for_io+0x3b/0xe0 >> [ 2536.250054] [<ffffffffa016fd52>] mpage_submit_page+0x52/0x80 [ext4] >> [ 2536.250054] [<ffffffffa016fe89>] mpage_process_page_bufs+0x109/0x140 [ext4] >> [ 2536.250054] [<ffffffffa01700d7>] mpage_prepare_extent_to_map+0x217/0x2d0 [ext4] >> [ 2536.250054] [<ffffffffa0174929>] ext4_writepages+0x469/0xca0 [ext4] >> [ 2536.250054] [<ffffffff8114cd3e>] do_writepages+0x1e/0x50 >> [ 2536.250054] [<ffffffff811d7716>] __writeback_single_inode+0x76/0x240 >> [ 2536.250054] [<ffffffff811d7c12>] writeback_sb_inodes+0x282/0x420 >> [ 2536.250054] [<ffffffff811d7e2f>] __writeback_inodes_wb+0x7f/0xd0 >> [ 2536.250054] [<ffffffff811d884b>] wb_writeback+0x15b/0x2a0 >> [ 2536.250054] [<ffffffff811d8fa7>] bdi_writeback_workfn+0x1d7/0x450 >> [ 2536.250054] [<ffffffff8107be4d>] process_one_work+0x25d/0x460 >> [ 2536.250054] [<ffffffff8107d196>] worker_thread+0x266/0x480 >> [ 2536.250054] [<ffffffff8107cf30>] ? manage_workers.isra.18+0x3f0/0x3f0 >> [ 2536.250054] [<ffffffff81083bcb>] kthread+0xbb/0xd0 >> [ 2536.250054] [<ffffffff81083b10>] ? kthread_stop+0xf0/0xf0 >> [ 2536.250054] [<ffffffff814d4dbc>] ret_from_fork+0x7c/0xb0 >> [ 2536.250054] [<ffffffff81083b10>] ? kthread_stop+0xf0/0xf0 >> [ 2536.250054] Code: 00 74 70 48 63 35 d1 1f a1 00 ba ff ff ff ff eb 29 66 90 48 98 48 8b 0b 48 03 0c c5 00 27 ad 81 f6 41 20 01 74 14 0f 1f 44 00 00 <f3> 90 f6 41 20 01 75 f8 48 63 35 a1 1f a1 00 48 8b 7b 08 83 c2 >> [ 2544.900055] BUG: soft lockup - CPU#31 stuck for 24s! [systemd-journal:304] >> [ 2544.900055] Modules linked in: isofs crct10dif_pclmul crct10dif_common crc32_pclmul crc32c_intel ghash_clmulni_intel aesni_intel aes_x86_64 lrw gf128mul glue_helper ablk_helper cryptd raid0 md_mod acpi_cpufreq psmouse i2c_piix4 intel_agp intel_gtt i2c_core processor serio_raw evdev microcode ext4 crc16 mbcache jbd2 ata_generic pata_acpi ata_piix libata scsi_mod floppy ixgbevf xen_privcmd xen_netfront xen_kbdfront syscopyarea sysfillrect sysimgblt fb_sys_fops xen_blkfront virtio_pci virtio_net virtio_blk virtio_ring virtio ipmi_poweroff ipmi_msghandler button >> [ 2544.900055] CPU: 31 PID: 304 Comm: systemd-journal Tainted: G W 3.12.0-rc4-bisect-00073-g6fe6b2d #26 >> [ 2544.900055] Hardware name: Xen HVM domU, BIOS 4.2.amazon 01/14/2014 >> [ 2544.900055] task: ffff880764bcb400 ti: ffff8807653f6000 task.ti: ffff8807653f6000 >> [ 2544.900055] RIP: 0010:[<ffffffff810cc040>] [<ffffffff810cc040>] generic_exec_single+0x80/0xa0 >> [ 2544.900055] RSP: 0018:ffff8807653f7c80 EFLAGS: 00000202 >> [ 2544.900055] RAX: 0000000000000080 RBX: ffffffff813207fd RCX: 0000000000000080 >> [ 2544.900055] RDX: 0000000000000001 RSI: 0000000000000000 RDI: 0000000000000080 >> [ 2544.900055] RBP: ffff8807653f7cb0 R08: ffffffff8160d148 R09: ffff880770c006a8 >> [ 2544.900055] R10: 0000000000000020 R11: ffffea003b490700 R12: ffffffff810b859e >> [ 2544.900055] R13: ffff8807653f7bf8 R14: ffffffff810b50e7 R15: ffff8807653f7be8 >> [ 2544.900055] FS: 00007f0c934cd780(0000) GS:ffff880ef0fe0000(0000) knlGS:0000000000000000 >> [ 2544.900055] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 >> [ 2544.900055] CR2: 00007f0c934db000 CR3: 0000000764b0f000 CR4: 00000000001406e0 >> [ 2544.900055] Stack: >> [ 2544.900055] 0000000106038000 000000000000000f 000000000000001f ffffffff81adcfe0 >> [ 2544.900055] ffffffff810564e0 000000000000001f ffff8807653f7d20 ffffffff810cc195 >> [ 2544.900055] 00007f0c934db000 ffff8807653f7cd8 ffff880ef0ef74a8 ffff880ef0ef4d00 >> [ 2544.900055] Call Trace: >> [ 2544.900055] [<ffffffff810564e0>] ? leave_mm+0x70/0x70 >> [ 2544.900055] [<ffffffff810cc195>] smp_call_function_single+0x135/0x170 >> [ 2544.900055] [<ffffffff810564e0>] ? leave_mm+0x70/0x70 >> [ 2544.900055] [<ffffffff810cc3c5>] smp_call_function_many+0x105/0x2b0 >> [ 2544.900055] [<ffffffff810564e0>] ? leave_mm+0x70/0x70 >> [ 2544.900055] [<ffffffff81056637>] native_flush_tlb_others+0x37/0x40 >> [ 2544.900055] [<ffffffff810568ae>] flush_tlb_mm_range+0x1fe/0x250 >> [ 2544.900055] [<ffffffff81167917>] tlb_flush_mmu+0x37/0xa0 >> [ 2544.900055] [<ffffffff81167994>] tlb_finish_mmu+0x14/0x50 >> [ 2544.900055] [<ffffffff8116fdc5>] unmap_region+0x105/0x120 >> [ 2544.900055] [<ffffffff811cd01e>] ? mntput_no_expire+0x3e/0x140 >> [ 2544.900055] [<ffffffff81170349>] ? vma_rb_erase+0x1c9/0x210 >> [ 2544.900055] [<ffffffff81171f10>] do_munmap+0x280/0x370 >> [ 2544.900055] [<ffffffff81172041>] vm_munmap+0x41/0x60 >> [ 2544.900055] [<ffffffff81172f42>] SyS_munmap+0x22/0x30 >> [ 2544.900055] [<ffffffff814d4e6d>] system_call_fastpath+0x1a/0x1f >> [ 2544.900055] Code: 48 89 4b 08 48 89 19 e8 4f 05 40 00 4d 39 fc 8b 55 d4 75 0f 44 89 f7 ff 15 5e 8d 95 00 8b 55 d4 0f 1f 00 85 d2 75 06 eb 0a 66 90 <f3> 90 f6 43 20 01 75 f8 48 83 c4 08 5b 41 5c 41 5d 41 5e 41 5f >> >> At this point, the MD array will not accept any I/O, and any requests will just >> result in additional soft lockup messages. >> >> I originally noticed this issue on Linux 3.13.3, and wasn't able to reproduce >> it on 3.10.30. I eventually narrowed it down to a regression introduced between >> 3.12 and 3.13. A bisection blames this commit: >> >> commit b795854b1fa70f6aee923ae5df74ff7afeaddcaa >> Author: Mel Gorman <mgorman@...e.de> >> Date: Mon Oct 7 11:29:07 2013 +0100 >> >> sched/numa: Set preferred NUMA node based on number of private faults >> >> Ideally it would be possible to distinguish between NUMA hinting faults that >> are private to a task and those that are shared. If treated identically >> there is a risk that shared pages bounce between nodes depending on >> the order they are referenced by tasks. Ultimately what is desirable is >> that task private pages remain local to the task while shared pages are >> interleaved between sharing tasks running on different nodes to give good >> average performance. This is further complicated by THP as even >> applications that partition their data may not be partitioning on a huge >> page boundary. >> >> To start with, this patch assumes that multi-threaded or multi-process >> applications partition their data and that in general the private accesses >> are more important for cpu->memory locality in the general case. Also, >> no new infrastructure is required to treat private pages properly but >> interleaving for shared pages requires additional infrastructure. >> >> To detect private accesses the pid of the last accessing task is required >> but the storage requirements are a high. This patch borrows heavily from >> Ingo Molnar's patch "numa, mm, sched: Implement last-CPU+PID hash tracking" >> to encode some bits from the last accessing task in the page flags as >> well as the node information. Collisions will occur but it is better than >> just depending on the node information. Node information is then used to >> determine if a page needs to migrate. The PID information is used to detect >> private/shared accesses. The preferred NUMA node is selected based on where >> the maximum number of approximately private faults were measured. Shared >> faults are not taken into consideration for a few reasons. >> >> First, if there are many tasks sharing the page then they'll all move >> towards the same node. The node will be compute overloaded and then >> scheduled away later only to bounce back again. Alternatively the shared >> tasks would just bounce around nodes because the fault information is >> effectively noise. Either way accounting for shared faults the same as >> private faults can result in lower performance overall. >> >> The second reason is based on a hypothetical workload that has a small >> number of very important, heavily accessed private pages but a large shared >> array. The shared array would dominate the number of faults and be selected >> as a preferred node even though it's the wrong decision. >> >> The third reason is that multiple threads in a process will race each >> other to fault the shared page making the fault information unreliable. >> >> Signed-off-by: Mel Gorman <mgorman@...e.de> >> [ Fix complication error when !NUMA_BALANCING. ] >> Reviewed-by: Rik van Riel <riel@...hat.com> >> Cc: Andrea Arcangeli <aarcange@...hat.com> >> Cc: Johannes Weiner <hannes@...xchg.org> >> Cc: Srikar Dronamraju <srikar@...ux.vnet.ibm.com> >> Signed-off-by: Peter Zijlstra <peterz@...radead.org> >> Link: http://lkml.kernel.org/r/1381141781-10992-30-git-send-email-mgorman@suse.de >> Signed-off-by: Ingo Molnar <mingo@...nel.org> >> >> Here's the bisection log: >> >> # bad: [d8ec26d7] Linux 3.13 >> # good: [5e01dc7b] Linux 3.12 >> # bad: [42a2d923] Merge git://git.kernel.org/pub/scm/linux/kernel/gi >> # bad: [4b4d2b46] Merge tag 'h8300-for-linus' of git://git.kernel.or >> # skip: [c224b76b] Merge tag 'nfs-for-3.13-1' of git://git.linux-nfs. >> # good: [ae1dd9bc] Staging: xillybus: quoted strings split across lin >> # good: [beb5bfe4] Merge tag 'fixes-nc-for-linus' of git://git.kernel >> # good: [f9efbce6] Merge tag 'dt-for-linus' of git://git.kernel.org/p >> # good: [ad5d6989] Merge branch 'perf-core-for-linus' of git://git.ke >> # bad: [39cf275a] Merge branch 'sched-core-for-linus' of git://git.k >> # good: [e6628d5b] sched/numa: Reschedule task on preferred NUMA node >> # bad: [04bb2f94] sched/numa: Adjust scan rate in task_numa_placemen >> # bad: [e1dda8a7] sched/numa: Fix placement of workloads spread acro >> # bad: [58d081b5] sched/numa: Avoid overloading CPUs on a preferred >> # good: [073b5bee] sched/numa: Remove check that skips small VMAs >> # bad: [6fe6b2d6] sched/numa: Do not migrate memory immediately afte >> # bad: [b795854b] sched/numa: Set preferred NUMA node based on numbe >> >> Anyone have any ideas why this change broke things? Is there any additional >> information I can provide to help pin this down? >> >> - Steven -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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