Re: [Xen-devel] [PATCH 00/13] mmu_notifier kill invalidate_page callback

[Jeff Cook <jeff@xxxxxxxxxxx>]

On Wed, Aug 30, 2017, at 10:57 AM, Adam Borowski wrote:
> On Tue, Aug 29, 2017 at 08:56:15PM -0400, Jerome Glisse wrote:
> > I will wait for people to test and for result of my own test before
> > reposting if need be, otherwise i will post as separate patch.
> >
> > > But from a _very_ quick read-through this looks fine. But it obviously
> > > needs testing.
> > > 
> > > People - *especially* the people who saw issues under KVM - can you
> > > try out Jérôme's patch-series? I aded some people to the cc, the full
> > > series is on lkml. Jérôme - do you have a git branch for people to
> > > test that they could easily pull and try out?
> > 
> > https://cgit.freedesktop.org/~glisse/linux mmu-notifier branch
> > git://people.freedesktop.org/~glisse/linux
> 
> Tested your branch as of 10f07641, on a long list of guest VMs.
> No earth-shattering kaboom.

I've been using the mmu_notifier branch @ a3d944233bcf8c for the last 36
hours or so, also without incident.

Unlike most other reporters, I experienced a similar splat on 4.12:

Aug 03 15:02:47 kvm_master kernel: ------------[ cut here ]------------
Aug 03 15:02:47 kvm_master kernel: WARNING: CPU: 13 PID: 1653 at
arch/x86/kvm/mmu.c:682 mmu_spte_clear_track_bits+0xfb/0x100 [kvm]
Aug 03 15:02:47 kvm_master kernel: Modules linked in: vhost_net vhost
tap xt_conntrack xt_CHECKSUM iptable_mangle ipt_REJECT nf_reject_ipv4
xt_tcpudp tun ebtable_filter ebtables ip6table_filter ip6_tables
iptable_filter msr nls_iso8859_1 nls_cp437 intel_rapl ipt_
MASQUERADE nf_nat_masquerade_ipv4 iptable_nat nf_conntrack_ipv4
nf_defrag_ipv4 nf_nat_ipv4 nf_nat nf_conntrack sb_edac
x86_pkg_temp_thermal intel_powerclamp coretemp crct10dif_pclmul
crc32_pclmul ghash_clmulni_intel input_leds pcbc aesni_intel led_class
aes_x86_6
4 mxm_wmi crypto_simd glue_helper uvcvideo cryptd videobuf2_vmalloc
videobuf2_memops igb videobuf2_v4l2 videobuf2_core snd_usb_audio
videodev media joydev ptp evdev mousedev intel_cstate pps_core mac_hid
intel_rapl_perf snd_hda_intel snd_virtuoso snd_usbmidi_lib snd_hda_codec
snd_oxygen_lib snd_hda_core                        
Aug 03 15:02:47 kvm_master kernel:  snd_mpu401_uart snd_rawmidi
snd_hwdep snd_seq_device snd_pcm snd_timer snd soundcore i2c_algo_bit
pcspkr i2c_i801 lpc_ich ioatdma shpchp dca wmi acpi_power_meter tpm_tis
tpm_tis_core tpm button bridge stp llc sch_fq_codel virtio_pci
virtio_blk virtio_balloon virtio_net virtio_ring virtio kvm_intel kvm sg
ip_tables x_tables hid_logitech_hidpp hid_logitech_dj hid_generic
hid_microsoft usbhid hid sr_mod cdrom sd_mod xhci_pci ahci libahci
xhci_hcd libata usbcore scsi_mod usb_common zfs(PO) zunicode(PO)
zavl(PO) icp(PO) zcommon(PO) znvpair(PO) spl(O) drm_kms_helper
syscopyarea sysfillrect sysimgblt fb_sys_fops drm vfio_pci irqbypass
vfio_virqfd vfio_iommu_type1 vfio vfat fat ext4 crc16 jbd2 fscrypto
mbcache dm_thin_pool dm_cache dm_persistent_data dm_bio_prison dm_bufio
dm_raid raid456 libcrc32c                 
Aug 03 15:02:47 kvm_master kernel:  crc32c_generic crc32c_intel
async_raid6_recov async_memcpy async_pq async_xor xor async_tx raid6_pq
dm_mod dax raid1 md_mod                                                  
Aug 03 15:02:47 kvm_master kernel: CPU: 13 PID: 1653 Comm: kworker/13:2
Tainted: P    B D W  O    4.12.3-1-ARCH #1                 
Aug 03 15:02:47 kvm_master kernel: Hardware name: Supermicro
SYS-7038A-I/X10DAI, BIOS 2.0a 11/09/2016                              
Aug 03 15:02:47 kvm_master kernel: Workqueue: events mmput_async_fn      
Aug 03 15:02:47 kvm_master kernel: task: ffff9fa89751b900 task.stack:
ffffc179880d8000                                             
Aug 03 15:02:47 kvm_master kernel: RIP:
0010:mmu_spte_clear_track_bits+0xfb/0x100 [kvm]                          
Aug 03 15:02:47 kvm_master kernel: RSP: 0018:ffffc179880dbc20 EFLAGS:
00010246                                                     
Aug 03 15:02:47 kvm_master kernel: RAX: 0000000000000000 RBX:
00000009c07cce77 RCX: dead0000000000ff                               
Aug 03 15:02:47 kvm_master kernel: RDX: 0000000000000000 RSI:
ffff9fa82d6d6f08 RDI: fffff6e76701f300                               
Aug 03 15:02:47 kvm_master kernel: RBP: ffffc179880dbc38 R08:
0000000000100000 R09: 000000000000000d                               
Aug 03 15:02:47 kvm_master kernel: R10: ffff9fa0a56b0008 R11:
ffff9fa0a56b0000 R12: 00000000009c07cc                               
Aug 03 15:02:47 kvm_master kernel: R13: ffff9fa88b990000 R14:
ffff9f9e19dbb1b8 R15: 0000000000000000                               
Aug 03 15:02:47 kvm_master kernel: FS:  0000000000000000(0000)
GS:ffff9fac5f340000(0000) knlGS:0000000000000000                    
Aug 03 15:02:47 kvm_master kernel: CS:  0010 DS: 0000 ES: 0000 CR0:
0000000080050033                                               
Aug 03 15:02:47 kvm_master kernel: CR2: ffffd1b542d71000 CR3:
0000000570a09000 CR4: 00000000003426e0                               
Aug 03 15:02:47 kvm_master kernel: DR0: 0000000000000000 DR1:
0000000000000000 DR2: 0000000000000000                               
Aug 03 15:02:47 kvm_master kernel: DR3: 0000000000000000 DR6:
00000000fffe0ff0 DR7: 0000000000000400                               
Aug 03 15:02:47 kvm_master kernel: Call Trace:                   
Aug 03 15:02:47 kvm_master kernel:  drop_spte+0x1a/0xb0 [kvm]    
Aug 03 15:02:47 kvm_master kernel:  mmu_page_zap_pte+0x9c/0xe0 [kvm]     
Aug 03 15:02:47 kvm_master kernel:  kvm_mmu_prepare_zap_page+0x65/0x310
[kvm]
Aug 03 15:02:47 kvm_master kernel: 
kvm_mmu_invalidate_zap_all_pages+0x10d/0x160 [kvm]
Aug 03 15:02:47 kvm_master kernel:  kvm_arch_flush_shadow_all+0xe/0x10
[kvm]
Aug 03 15:02:47 kvm_master kernel:  kvm_mmu_notifier_release+0x2c/0x40
[kvm]
Aug 03 15:02:47 kvm_master kernel:  __mmu_notifier_release+0x44/0xc0
Aug 03 15:02:47 kvm_master kernel:  exit_mmap+0x142/0x150
Aug 03 15:02:47 kvm_master kernel:  ? kfree+0x175/0x190
Aug 03 15:02:47 kvm_master kernel:  ? kfree+0x175/0x190
Aug 03 15:02:47 kvm_master kernel:  ? exit_aio+0xc6/0x100
Aug 03 15:02:47 kvm_master kernel:  mmput_async_fn+0x4c/0x130
Aug 03 15:02:47 kvm_master kernel:  process_one_work+0x1de/0x430
Aug 03 15:02:47 kvm_master kernel:  worker_thread+0x47/0x3f0
Aug 03 15:02:47 kvm_master kernel:  kthread+0x125/0x140
Aug 03 15:02:47 kvm_master kernel:  ? process_one_work+0x430/0x430
Aug 03 15:02:47 kvm_master kernel:  ? kthread_create_on_node+0x70/0x70
Aug 03 15:02:47 kvm_master kernel:  ret_from_fork+0x25/0x30
Aug 03 15:02:47 kvm_master kernel: Code: ec 75 04 00 48 b8 00 00 00 00
00 00 00 40 48 21 da 48 39 c2 0f 95 c0 eb b2 48 d1 eb 83 e3 01 eb c0 4c
89 e7 e8 f7 3d fe ff eb a4 <0f> ff eb 8a 90 0f 1f 44 00 00 55 48 89 e5
53 89 d3 e8 ff 4a fe 
Aug 03 15:02:47 kvm_master kernel: ---[ end trace 8710f4d700a7d36e ]---

This would typically take 36-48 hours to surface, so we're good so far,
but not completely out of the woods yet. I'm optimistic that since this
patchset changes the mmu_notifier behavior to something safer in
general, this issue will also be resolved by it.

Jeff

> 
> 
> Meow!
> -- 
> ⢀⣴⠾⠻⢶⣦⠀ 
> ⣾⠁⢰⠒⠀⣿⡁ Vat kind uf sufficiently advanced technology iz dis!?
> ⢿⡄⠘⠷⠚⠋⠀                                 -- Genghis Ht'rok'din
> ⠈⠳⣄⠀⠀⠀⠀ 

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