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

[Yonglong Liu <liuyonglong@huawei.com>]

On 2024/7/31 19:32, Yonglong Liu wrote:
>
> 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:
>>>
>>>
>>> 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?
>
> I found that this happen when the vf enabled and running some packets, 
> below is more infomation:
>
>
> [ 4391.596558] pci 0000:7d:01.0: page_pool_release_retry() stalled 
> pool shutdown: id 1145, 33 inflight 906 sec
> [ 4397.111484] hns3 0000:bd:00.0: SRIOV setting: 0
> [ 4397.118155] hns3 0000:bd:01.0 enp189s0f0v0: link down
> [ 4397.416623] hns3 0000:bd:01.0: finished uninitializing hclgevf driver
> [ 4397.480572] pci 0000:7d:01.0: page_pool_release_retry() stalled 
> pool shutdown: id 1279, 98 inflight 362 sec
> [ 4400.948362] hns3 0000:7d:00.0: SRIOV setting: 1
> [ 4401.060569] pci 0000:7d:01.0: [19e5:a22f] type 00 class 0x020000 
> PCIe Endpoint
> [ 4401.067795] pci 0000:7d:01.0: enabling Extended Tags
> [ 4401.073090] hns3 0000:7d:01.0: Adding to iommu group 48
> [ 4401.078494] hns3 0000:7d:01.0: enabling device (0000 -> 0002)
> [ 4401.084348] hns3 0000:7d:01.0: The firmware version is 1.20.0.17
> [ 4401.102911] hns3 0000:7d:01.0: finished initializing hclgevf driver
> [ 4401.111212] hns3 0000:7d:01.0: using random MAC address 
> da:**:**:**:a3:47
> [ 4401.138375] hns3 0000:7d:01.0 eno1v0: renamed from eth0
> [ 4403.939449] hns3 0000:7d:01.0 eno1v0: link up
> [ 4403.940237] 8021q: adding VLAN 0 to HW filter on device eno1v0
> [ 4406.956606] Unable to handle kernel NULL pointer dereference at 
> virtual address 00000000000000a8
>
>
> another log:
>
> [11550.197002] hns3 0000:bd:01.0 enp189s0f0v0: link up
> [11550.197034] hns3 0000:bd:01.0 enp189s0f0v0: net open
> [11550.206910] 8021q: adding VLAN 0 to HW filter on device enp189s0f0v0
> [11564.872929] page_pool_release_retry() stalled pool shutdown: id 
> 2330, 99 inflight 60 sec
> [11568.353723] hns3 0000:bd:01.0 enp189s0f0v0: net stop
> [11568.360723] hns3 0000:bd:01.0 enp189s0f0v0: link down
> [11568.519899] hns3 0000:bd:01.0 enp189s0f0v0: link up
> [11568.519935] hns3 0000:bd:01.0 enp189s0f0v0: net open
> [11568.529840] 8021q: adding VLAN 0 to HW filter on device enp189s0f0v0
> [11589.640930] page_pool_release_retry() stalled pool shutdown: id 
> 1996, 50 inflight 2054 sec
> [11592.554875] hns3 0000:bd:01.0 enp189s0f0v0: net stop
> [11592.560930] hns3 0000:bd:01.0 enp189s0f0v0: link down
> [11596.684935] pci 0000:7d:01.0: [19e5:a22f] type 00 class 0x020000 
> PCIe Endpoint
> [11596.692140] pci 0000:7d:01.0: enabling Extended Tags
> [11596.697324] hns3 0000:7d:01.0: Adding to iommu group 48
> [11596.702988] hns3 0000:7d:01.0: enabling device (0000 -> 0002)
> [11596.708808] hns3 0000:7d:01.0: The firmware version is 1.20.0.17
> [11596.727263] hns3 0000:7d:01.0: finished initializing hclgevf driver
> [11596.735561] hns3 0000:7d:01.0: using random MAC address 
> 72:**:**:**:55:d7
> [11596.760621] hns3 0000:7d:01.0 eno1v0: renamed from eth0
> [11599.545341] hns3 0000:7d:01.0 eno1v0: link up
> [11599.545409] hns3 0000:7d:01.0 eno1v0: net open
> [11599.554858] 8021q: adding VLAN 0 to HW filter on device eno1v0
> [11608.908922] Unable to handle kernel NULL pointer dereference at 
> virtual address 00000000000000a8
>
I adds more debug info, and found that:

[ 4573.356891] pci 0000:7d:01.0: page_pool_release_retry() stalled pool 
shutdown: id 1046, 82 inflight 60 sec, iommu_group=0x0

The iommu_group will release whether the page_pool is using it or not, 
so if once page_pool_return_page() was called(why does this occur when 
the device is reloaded and packets are transmitted?) , this crash will 
happen.

I try the follow patch, but doesn't work :(

diff --git a/net/core/page_pool.c b/net/core/page_pool.c
index f4444b4e39e6..d03a87407ca8 100644
--- a/net/core/page_pool.c
+++ b/net/core/page_pool.c
@@ -21,6 +21,7 @@
  #include <linux/poison.h>
  #include <linux/ethtool.h>
  #include <linux/netdevice.h>
+#include <linux/iommu.h>

  #include <trace/events/page_pool.h>

@@ -306,6 +307,9 @@ page_pool_create_percpu(const struct 
page_pool_params *params, int cpuid)
         if (err)
                 goto err_uninit;

+       if (pool->dma_map)
+               iommu_group_get(pool->p.dev);
+
         return pool;

  err_uninit:
@@ -974,8 +978,11 @@ static int page_pool_release(struct page_pool *pool)

         page_pool_scrub(pool);
         inflight = page_pool_inflight(pool, true);
-       if (!inflight)
+       if (!inflight) {
                 __page_pool_destroy(pool);
+               if (pool->dma_map)
+ iommu_group_put(pool->p.dev->iommu_group);
+       }

         return inflight;
  }


>>> 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) ???
>>>
>>>
>>>> [ 4407.212119] process_one_work+0x164/0x3e0
>>>> [ 4407.216116]  worker_thread+0x310/0x420
>>>> [ 4407.219851]  kthread+0x120/0x130
>>>> [ 4407.223066]  ret_from_fork+0x10/0x20
>>>> [ 4407.226630] Code: ffffc318 aa1e03e9 d503201f f9416c00 (f9405400)
>>>> [ 4407.232697] ---[ end trace 0000000000000000 ]---
>>>>
>>>>
>>>> The hns3 driver use page pool like this, just call once when the 
>>>> driver
>>>> initialize:
>>>>
>>>> static void hns3_alloc_page_pool(struct hns3_enet_ring *ring)
>>>> {
>>>>       struct page_pool_params pp_params = {
>>>>           .flags = PP_FLAG_DMA_MAP | PP_FLAG_PAGE_FRAG |
>>>>                   PP_FLAG_DMA_SYNC_DEV,
>>>>           .order = hns3_page_order(ring),
>>>>           .pool_size = ring->desc_num * hns3_buf_size(ring) /
>>>>                   (PAGE_SIZE << hns3_page_order(ring)),
>>>>           .nid = dev_to_node(ring_to_dev(ring)),
>>>>           .dev = ring_to_dev(ring),
>>>>           .dma_dir = DMA_FROM_DEVICE,
>>>>           .offset = 0,
>>>>           .max_len = PAGE_SIZE << hns3_page_order(ring),
>>>>       };
>>>>
>>>>       ring->page_pool = page_pool_create(&pp_params);
>>>>       if (IS_ERR(ring->page_pool)) {
>>>>           dev_warn(ring_to_dev(ring), "page pool creation failed: 
>>>> %ld\n",
>>>>                PTR_ERR(ring->page_pool));
>>>>           ring->page_pool = NULL;
>>>>       }
>>>> }
>>>>
>>>> And call page_pool_destroy(ring->page_pool)  when the driver 
>>>> uninitialized.
>>>>
>>>>
>>>> We use two devices, the net port connect directory, and the step of 
>>>> the
>>>> test case like below:
>>>>
>>>> 1. enable a vf of '7d:00.0':  echo 1 >
>>>> /sys/class/net/eno1/device/sriov_numvfs
>>>>
>>>> 2. use iperf to produce some flows(the problem happens to the side 
>>>> which
>>>> runs 'iperf -s')
>>>>
>>>> 3. use ifconfig down/up to the vf
>>>>
>>>> 4. kill iperf
>>>>
>>>> 5. disable the vf: echo 0 > /sys/class/net/eno1/device/sriov_numvfs
>>>>
>>>> 6. run 1~5 with another port bd:00.0
>>>>
>>>> 7. repeat 1~6
>>>>
>>>>
>>>> And when running this test case, we can found another related 
>>>> message (I
>>>> replaced pr_warn() to dev_warn()):
>>>>
>>>> pci 0000:7d:01.0: page_pool_release_retry() stalled pool shutdown: id
>>>> 949, 98 inflight 1449 sec
>>>>
>>>>
>>>> Even when stop the traffic, stop the test case, disable the vf, this
>>>> message is still being printed.
>>>>
>>>> We must run the test case for about two hours to reproduce the 
>>>> problem.
>>>> Is there some advise to solve or debug the problem?
>>>>
>