Re: [BUG REPORT]net: page_pool: kernel crash at iommu_get_dma_domain+0xc/0x20

[Yunsheng Lin <linyunsheng@huawei.com>]

On 2024/7/31 16:42, Somnath Kotur wrote:
> On Tue, Jul 30, 2024 at 10:51 PM Jesper Dangaard Brouer <hawk@kernel.org> wrote:
>>

+cc iommu maintainers and list

>>
>> On 30/07/2024 15.08, Yonglong Liu wrote:
>>> I found a bug when running hns3 driver with page pool enabled, the log
>>> as below:
>>>
>>> [ 4406.956606] Unable to handle kernel NULL pointer dereference at
>>> virtual address 00000000000000a8
>>
>> struct iommu_domain *iommu_get_dma_domain(struct device *dev)
>> {
>>         return dev->iommu_group->default_domain;
>> }
>>
>> $ pahole -C iommu_group --hex | grep default_domain
>>         struct iommu_domain *      default_domain;   /*  0xa8   0x8 */
>>
>> Looks like iommu_group is a NULL pointer (that when deref member
>> 'default_domain' cause this fault).
>>
>>
>>> [ 4406.965379] Mem abort info:
>>> [ 4406.968160]   ESR = 0x0000000096000004
>>> [ 4406.971906]   EC = 0x25: DABT (current EL), IL = 32 bits
>>> [ 4406.977218]   SET = 0, FnV = 0
>>> [ 4406.980258]   EA = 0, S1PTW = 0
>>> [ 4406.983404]   FSC = 0x04: level 0 translation fault
>>> [ 4406.988273] Data abort info:
>>> [ 4406.991154]   ISV = 0, ISS = 0x00000004, ISS2 = 0x00000000
>>> [ 4406.996632]   CM = 0, WnR = 0, TnD = 0, TagAccess = 0
>>> [ 4407.001681]   GCS = 0, Overlay = 0, DirtyBit = 0, Xs = 0
>>> [ 4407.006985] user pgtable: 4k pages, 48-bit VAs, pgdp=0000202828326000
>>> [ 4407.013430] [00000000000000a8] pgd=0000000000000000,
>>> p4d=0000000000000000
>>> [ 4407.020212] Internal error: Oops: 0000000096000004 [#1] PREEMPT SMP
>>> [ 4407.026454] Modules linked in: hclgevf xt_CHECKSUM ipt_REJECT
>>> nf_reject_ipv4 ip6table_mangle ip6table_nat iptable_mangle
>>> ip6table_filter ip6_tables hns_roce_hw_v2 hns3 hclge hnae3 xt_addrtype
>>> iptable_filter xt_conntrack overlay arm_spe_pmu arm_smmuv3_pmu
>>> hisi_uncore_hha_pmu hisi_uncore_ddrc_pmu hisi_uncore_l3c_pmu
>>> hisi_uncore_pmu fuse rpcrdma ib_isert iscsi_target_mod ib_iser libiscsi
>>> scsi_transport_iscsi crct10dif_ce hisi_sec2 hisi_hpre hisi_zip
>>> hisi_sas_v3_hw xhci_pci sbsa_gwdt hisi_qm hisi_sas_main hisi_dma
>>> xhci_pci_renesas uacce libsas [last unloaded: hnae3]
>>> [ 4407.076027] CPU: 48 PID: 610 Comm: kworker/48:1
>>> [ 4407.093343] Workqueue: events page_pool_release_retry
>>> [ 4407.098384] pstate: 60400009 (nZCv daif +PAN -UAO -TCO -DIT -SSBS
>>> BTYPE=--)
>>> [ 4407.105316] pc : iommu_get_dma_domain+0xc/0x20
>>> [ 4407.109744] lr : iommu_dma_unmap_page+0x38/0xe8
>>> [ 4407.114255] sp : ffff80008bacbc80
>>> [ 4407.117554] x29: ffff80008bacbc80 x28: 0000000000000000 x27:
>>> ffffc31806be7000
>>> [ 4407.124659] x26: ffff2020002b6ac0 x25: 0000000000000000 x24:
>>> 0000000000000002
>>> [ 4407.131762] x23: 0000000000000022 x22: 0000000000001000 x21:
>>> 00000000fcd7c000
>>> [ 4407.138865] x20: ffff0020c9882800 x19: ffff0020856f60c8 x18:
>>> ffff8000d3503c58
>>> [ 4407.145968] x17: 0000000000000000 x16: 1fffe00419521061 x15:
>>> 0000000000000001
>>> [ 4407.153073] x14: 0000000000000003 x13: 00000401850ae012 x12:
>>> 000006b10004e7fb
>>> [ 4407.160177] x11: 0000000000000067 x10: 0000000000000c70 x9 :
>>> ffffc3180405cd20
>>> [ 4407.167280] x8 : fefefefefefefeff x7 : 0000000000000001 x6 :
>>> 0000000000000010
>>> [ 4407.174382] x5 : ffffc3180405cce8 x4 : 0000000000000022 x3 :
>>> 0000000000000002
>>> [ 4407.181485] x2 : 0000000000001000 x1 : 00000000fcd7c000 x0 :
>>> 0000000000000000
>>> [ 4407.188589] Call trace:
>>> [ 4407.191027]  iommu_get_dma_domain+0xc/0x20
>>> [ 4407.195105]  dma_unmap_page_attrs+0x38/0x1d0
>>> [ 4407.199361]  page_pool_return_page+0x48/0x180
>>> [ 4407.203699]  page_pool_release+0xd4/0x1f0
>>> [ 4407.207692]  page_pool_release_retry+0x28/0xe8
>>
>> I suspect that the DMA IOMMU part was deallocated and freed by the
>> driver even-though page_pool still have inflight packets.
> When you say driver, which 'driver' do you mean?
> I suspect this could be because of the VF instance going away with
> this cmd - disable the vf: echo 0 >
> /sys/class/net/eno1/device/sriov_numvfs, what do you think?
>>
>> The page_pool bumps refcnt via get_device() + put_device() on the DMA
>> 'struct device', to avoid it going away, but I guess there is also some
>> IOMMU code that we need to make sure doesn't go away (until all inflight
>> pages are returned) ???

I guess the above is why thing went wrong here, the question is which
IOMMU code need to be called here to stop them from going away.

What I am also curious is that there should be a pool of allocated iova in
iommu that is corresponding to the in-flight page for page_pool, shouldn't
iommu wait for the corresponding allocated iova to be freed similarly as
page_pool does for it's in-flight pages?