Re: Bug report: vfio over kernel 5.19 - mm area

[Yishai Hadas <yishaih@nvidia.com>]

On 15/06/2022 17:14, Yi Liu wrote:
> Hi Alex,
>
> On 2022/6/15 22:02, Alex Williamson wrote:
>> On Wed, 15 Jun 2022 13:52:10 +0300
>> Yishai Hadas <yishaih@nvidia.com> wrote:
>>
>>> Adding some extra relevant people from the MM area.
>>>
>>> On 15/06/2022 13:43, Yishai Hadas wrote:
>>>> Hi All,
>>>>
>>>> Any idea what could cause the below break in 5.19 ? we run QEMU and
>>>> immediately the machine is stuck.
>>>>
>>>> Once I run, echo l > /proc/sysrq-trigger could see the below task
>>>> which seems to be stuck..
>>>>
>>>> This basic flow worked fine in 5.18.
>>
>> Spent Friday bisecting this and posted this fix:
>>
>> https://lore.kernel.org/all/165490039431.944052.12458624139225785964.stgit@omen/ 
>>
>>
>> I expect you're hotting the same.  Thanks,
>
> I also hit a hang at calling pin_user_pages_remote() in the
> vaddr_get_pfns(). With the fix in the link, the issue got fixed.
> You may add my test-by to your fix. :-)


Thanks Alex, it seems to be the same issue, with your fix I don't hit 
the problem.


>
>> Alex
>>
>>>>
>>>> [1162.056583] NMI backtrace for cpu 4
>>>> [ 1162.056585] CPU: 4 PID: 1979 Comm: qemu-system-x86 Not tainted
>>>> 5.19.0-rc1 #747
>>>> [ 1162.056587] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009),
>>>> BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014
>>>> [ 1162.056588] RIP: 0010:pmd_huge+0x0/0x20
>>>> [ 1162.056592] Code: 49 89 44 24 28 48 8b 47 30 49 89 44 24 30 31 c0
>>>> 41 5c c3 5b b8 01 00 00 00 5d 41 5c c3 cc cc cc cc cc cc cc cc cc cc
>>>> cc cc cc <0f> 1f 44 00 00 31 c0 48 f7 c7 9f ff ff ff 74 0f 81 e7 81 00
>>>> 00 00
>>>> [ 1162.056594] RSP: 0018:ffff888146253b38 EFLAGS: 00000202
>>>> [ 1162.056596] RAX: ffff888101461980 RBX: ffff888146253bc0 RCX:
>>>> 000ffffffffff000
>>>> [ 1162.056597] RDX: ffff88814fa22000 RSI: 00007f9f68231000 RDI:
>>>> 000000010a6b6067
>>>> [ 1162.056598] RBP: ffff888111b90dc0 R08: 000000000002f424 R09:
>>>> 0000000000000001
>>>> [ 1162.056599] R10: ffffffff825c2a40 R11: 0000000000000a08 R12:
>>>> ffff88814fa22a08
>>>> [ 1162.056600] R13: 000000010a6b6067 R14: 0000000000052202 R15:
>>>> 00007f9f68231000
>>>> [ 1162.056602] FS:  00007f9f6c228c40(0000) GS:ffff88885f900000(0000)
>>>> knlGS:0000000000000000
>>>> [ 1162.056605] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>>>> [ 1162.056606] CR2: 00005643994fd0ed CR3: 00000001496da005 CR4:
>>>> 0000000000372ea0
>>>> [ 1162.056607] DR0: 0000000000000000 DR1: 0000000000000000 DR2:
>>>> 0000000000000000
>>>> [ 1162.056609] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7:
>>>> 0000000000000400
>>>> [ 1162.056610] Call Trace:
>>>> [ 1162.056611]  <TASK>
>>>> [ 1162.056611]  follow_page_mask+0x196/0x5e0
>>>> [ 1162.056615]  __get_user_pages+0x190/0x5d0
>>>> [ 1162.056617]  ? flush_workqueue_prep_pwqs+0x110/0x110
>>>> [ 1162.056620]  __gup_longterm_locked+0xaf/0x470
>>>> [ 1162.056624]  vaddr_get_pfns+0x8e/0x240 [vfio_iommu_type1]
>>>> [ 1162.056628]  ? qi_flush_iotlb+0x83/0xa0
>>>> [ 1162.056631]  vfio_pin_pages_remote+0x326/0x460 [vfio_iommu_type1]
>>>> [ 1162.056634]  vfio_iommu_type1_ioctl+0x421/0x14f0 [vfio_iommu_type1]
>>>> [ 1162.056638]  __x64_sys_ioctl+0x3e4/0x8e0
>>>> [ 1162.056641]  do_syscall_64+0x3d/0x90
>>>> [ 1162.056644]  entry_SYSCALL_64_after_hwframe+0x46/0xb0
>>>> [ 1162.056646] RIP: 0033:0x7f9f6d14317b
>>>> [ 1162.056648] Code: 0f 1e fa 48 8b 05 1d ad 0c 00 64 c7 00 26 00 00
>>>> 00 48 c7 c0 ff ff ff ff c3 66 0f 1f 44 00 00 f3 0f 1e fa b8 10 00 00
>>>> 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d ed ac 0c 00 f7 d8 64 89
>>>> 01 48
>>>> [ 1162.056650] RSP: 002b:00007fff4fca15b8 EFLAGS: 00000246 ORIG_RAX:
>>>> 0000000000000010
>>>> [ 1162.056652] RAX: ffffffffffffffda RBX: 0000000000000001 RCX:
>>>> 00007f9f6d14317b
>>>> [ 1162.056653] RDX: 00007fff4fca1620 RSI: 0000000000003b71 RDI:
>>>> 000000000000001c
>>>> [ 1162.056654] RBP: 00007fff4fca1650 R08: 0000000000000001 R09:
>>>> 0000000000000000
>>>> [ 1162.056655] R10: 0000000100000000 R11: 0000000000000246 R12:
>>>> 0000000000000000
>>>> [ 1162.056656] R13: 0000000000000000 R14: 0000000000000000 R15:
>>>> 0000000000000000
>>>> [ 1162.056657]  </TASK>
>>>>
>>>> Yishai
>>>
>>
>