Re: [PATCH v4 2/2] amd/amdkfd: enhance kfd process check in switch partition

[Philip Yang <yangp@amd.com>]

On 2025-09-24 11:29, Yifan Zhang wrote:
> current switch partition only check if kfd_processes_table is empty.
> kfd_prcesses_table entry is deleted in kfd_process_notifier_release, but
> kfd_process tear down is in kfd_process_wq_release.
>
> consider two processes:
>
> Process A (workqueue) -> kfd_process_wq_release -> Access kfd_node member
> Process B switch partition -> amdgpu_xcp_pre_partition_switch -> amdgpu_amdkfd_device_fini_sw
> -> kfd_node tear down.
>
> Process A and B may trigger a race as shown in dmesg log.
>
> This patch is to resolve the race by adding an atomic kfd_process counter
> kfd_processes_count, it increment as create kfd process, decrement as
> finish kfd_process_wq_release.
>
> v2: Put kfd_processes_count per kfd_dev, move decrement to kfd_process_destroy_pdds
> and bug fix. (Philip Yang)
>
> [3966658.307702] divide error: 0000 [#1] SMP NOPTI
> [3966658.350818]  i10nm_edac
> [3966658.356318] CPU: 124 PID: 38435 Comm: kworker/124:0 Kdump: loaded Tainted
> [3966658.356890] Workqueue: kfd_process_wq kfd_process_wq_release [amdgpu]
> [3966658.362839]  nfit
> [3966658.366457] RIP: 0010:kfd_get_num_sdma_engines+0x17/0x40 [amdgpu]
> [3966658.366460] Code: 00 00 e9 ac 81 02 00 66 66 2e 0f 1f 84 00 00 00 00 00 90 0f 1f 44 00 00 48 8b 4f 08 48 8b b7 00 01 00 00 8b 81 58 26 03 00 99 <f7> be b8 01 00 00 80 b9 70 2e 00 00 00 74 0b 83 f8 02 ba 02 00 00
> [3966658.380967]  x86_pkg_temp_thermal
> [3966658.391529] RSP: 0018:ffffc900a0edfdd8 EFLAGS: 00010246
> [3966658.391531] RAX: 0000000000000008 RBX: ffff8974e593b800 RCX: ffff888645900000
> [3966658.391531] RDX: 0000000000000000 RSI: ffff888129154400 RDI: ffff888129151c00
> [3966658.391532] RBP: ffff8883ad79d400 R08: 0000000000000000 R09: ffff8890d2750af4
> [3966658.391532] R10: 0000000000000018 R11: 0000000000000018 R12: 0000000000000000
> [3966658.391533] R13: ffff8883ad79d400 R14: ffffe87ff662ba00 R15: ffff8974e593b800
> [3966658.391533] FS:  0000000000000000(0000) GS:ffff88fe7f600000(0000) knlGS:0000000000000000
> [3966658.391534] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [3966658.391534] CR2: 0000000000d71000 CR3: 000000dd0e970004 CR4: 0000000002770ee0
> [3966658.391535] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> [3966658.391535] DR3: 0000000000000000 DR6: 00000000fffe07f0 DR7: 0000000000000400
> [3966658.391536] PKRU: 55555554
> [3966658.391536] Call Trace:
> [3966658.391674]  deallocate_sdma_queue+0x38/0xa0 [amdgpu]
> [3966658.391762]  process_termination_cpsch+0x1ed/0x480 [amdgpu]
> [3966658.399754]  intel_powerclamp
> [3966658.402831]  kfd_process_dequeue_from_all_devices+0x5b/0xc0 [amdgpu]
> [3966658.402908]  kfd_process_wq_release+0x1a/0x1a0 [amdgpu]
> [3966658.410516]  coretemp
> [3966658.434016]  process_one_work+0x1ad/0x380
> [3966658.434021]  worker_thread+0x49/0x310
> [3966658.438963]  kvm_intel
> [3966658.446041]  ? process_one_work+0x380/0x380
> [3966658.446045]  kthread+0x118/0x140
> [3966658.446047]  ? __kthread_bind_mask+0x60/0x60
> [3966658.446050]  ret_from_fork+0x1f/0x30
> [3966658.446053] Modules linked in: kpatch_20765354(OEK)
> [3966658.455310]  kvm
> [3966658.464534]  mptcp_diag xsk_diag raw_diag unix_diag af_packet_diag netlink_diag udp_diag act_pedit act_mirred act_vlan cls_flower kpatch_21951273(OEK) kpatch_18424469(OEK) kpatch_19749756(OEK)
> [3966658.473462]  idxd_mdev
> [3966658.482306]  kpatch_17971294(OEK) sch_ingress xt_conntrack amdgpu(OE) amdxcp(OE) amddrm_buddy(OE) amd_sched(OE) amdttm(OE) amdkcl(OE) intel_ifs iptable_mangle tcm_loop target_core_pscsi tcp_diag target_core_file inet_diag target_core_iblock target_core_user target_core_mod coldpgs kpatch_18383292(OEK) ip6table_nat ip6table_filter ip6_tables ip_set_hash_ipportip ip_set_hash_ipportnet ip_set_hash_ipport ip_set_bitmap_port xt_comment iptable_nat nf_nat iptable_filter ip_tables ip_set ip_vs_sh ip_vs_wrr ip_vs_rr ip_vs nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 sn_core_odd(OE) i40e overlay binfmt_misc tun bonding(OE) aisqos(OE) aisqos_hotfixes(OE) rfkill uio_pci_generic uio cuse fuse nf_tables nfnetlink intel_rapl_msr intel_rapl_common intel_uncore_frequency intel_uncore_frequency_common i10nm_edac nfit x86_pkg_temp_thermal intel_powerclamp coretemp kvm_intel kvm idxd_mdev
> [3966658.491237]  vfio_pci
> [3966658.501196]  vfio_pci vfio_virqfd mdev vfio_iommu_type1 vfio iax_crypto intel_pmt_telemetry iTCO_wdt intel_pmt_class iTCO_vendor_support irqbypass crct10dif_pclmul crc32_pclmul ghash_clmulni_intel rapl intel_cstate snd_hda_intel snd_intel_dspcfg snd_hda_codec snd_hda_core snd_hwdep snd_seq
> [3966658.508537]  vfio_virqfd
> [3966658.517569]  snd_seq_device ipmi_ssif isst_if_mbox_pci isst_if_mmio pcspkr snd_pcm idxd intel_uncore ses isst_if_common intel_vsec idxd_bus enclosure snd_timer mei_me snd i2c_i801 i2c_smbus mei i2c_ismt soundcore joydev acpi_ipmi ipmi_si ipmi_devintf ipmi_msghandler acpi_power_meter acpi_pad vfat fat
> [3966658.526851]  mdev
> [3966658.536096]  nfsd auth_rpcgss nfs_acl lockd grace slb_vtoa(OE) sunrpc dm_mod hookers mlx5_ib(OE) ast i2c_algo_bit drm_vram_helper drm_kms_helper syscopyarea sysfillrect sysimgblt fb_sys_fops drm_ttm_helper ttm mlx5_core(OE) mlxfw(OE)
> [3966658.540381]  vfio_iommu_type1
> [3966658.544341]  nvme mpt3sas tls drm nvme_core pci_hyperv_intf raid_class psample libcrc32c crc32c_intel mlxdevm(OE) i2c_core
> [3966658.551254]  vfio
> [3966658.558742]  scsi_transport_sas wmi pinctrl_emmitsburg sd_mod t10_pi sg ahci libahci libata rdma_ucm(OE) ib_uverbs(OE) rdma_cm(OE) iw_cm(OE) ib_cm(OE) ib_umad(OE) ib_core(OE) ib_ucm(OE) mlx_compat(OE)
> [3966658.563004]  iax_crypto
> [3966658.570988]  [last unloaded: diagnose]
> [3966658.571027] ---[ end trace cc9dbb180f9ae537 ]---
>
> Signed-off-by: Yifan Zhang <yifan1.zhang@amd.com>

Because kfd structure is kzalloc, on x86, atomic_set 0 is not needed, I 
don't know other platforms. To be safe,

@@ -495,6 +495,7 @@ struct kfd_dev *kgd2kfd_probe(struct amdgpu_device 
*adev, bool vf)
         mutex_init(&kfd->doorbell_mutex);

         ida_init(&kfd->doorbell_ida);
+       atomic_set(&kfd->kfd_processes_count, 0);

         return kfd;
  }

With this added, this patch is Reviewed-by: Philip.Yang<Philip.Yang@amd.com>

> ---
>   drivers/gpu/drm/amd/amdkfd/kfd_device.c  | 9 +++++++++
>   drivers/gpu/drm/amd/amdkfd/kfd_priv.h    | 2 ++
>   drivers/gpu/drm/amd/amdkfd/kfd_process.c | 4 ++++
>   3 files changed, 15 insertions(+)
>
> diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_device.c b/drivers/gpu/drm/amd/amdkfd/kfd_device.c
> index 051a00152b08..488c8c0e6ccd 100644
> --- a/drivers/gpu/drm/amd/amdkfd/kfd_device.c
> +++ b/drivers/gpu/drm/amd/amdkfd/kfd_device.c
> @@ -1493,6 +1493,15 @@ int kgd2kfd_check_and_lock_kfd(struct kfd_dev *kfd)
>   
>   	mutex_lock(&kfd_processes_mutex);
>   
> +	/* kfd_processes_count is per kfd_dev, return -EBUSY without
> +	 * further check
> +	 */
> +	if (!!atomic_read(&kfd->kfd_processes_count)) {
> +		pr_debug("process_wq_release not finished\n");
> +		r = -EBUSY;
> +		goto out;
> +	}
> +
>   	if (hash_empty(kfd_processes_table) && !kfd_is_locked(kfd))
>   		goto out;
>   
> diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_priv.h b/drivers/gpu/drm/amd/amdkfd/kfd_priv.h
> index d01ef5ac0766..70ef051511bb 100644
> --- a/drivers/gpu/drm/amd/amdkfd/kfd_priv.h
> +++ b/drivers/gpu/drm/amd/amdkfd/kfd_priv.h
> @@ -382,6 +382,8 @@ struct kfd_dev {
>   
>   	/* for dynamic partitioning */
>   	int kfd_dev_lock;
> +
> +	atomic_t kfd_processes_count;
>   };
>   
>   enum kfd_mempool {
> diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_process.c b/drivers/gpu/drm/amd/amdkfd/kfd_process.c
> index 5be28c6c4f6a..ddfe30c13e9d 100644
> --- a/drivers/gpu/drm/amd/amdkfd/kfd_process.c
> +++ b/drivers/gpu/drm/amd/amdkfd/kfd_process.c
> @@ -1088,6 +1088,8 @@ static void kfd_process_destroy_pdds(struct kfd_process *p)
>   			pdd->runtime_inuse = false;
>   		}
>   
> +		atomic_dec(&pdd->dev->kfd->kfd_processes_count);
> +
>   		kfree(pdd);
>   		p->pdds[i] = NULL;
>   	}
> @@ -1649,6 +1651,8 @@ struct kfd_process_device *kfd_create_process_device_data(struct kfd_node *dev,
>   	/* Init idr used for memory handle translation */
>   	idr_init(&pdd->alloc_idr);
>   
> +	atomic_inc(&dev->kfd->kfd_processes_count);
> +
>   	return pdd;
>   }
>