From: Zhenyu Wang zhenyuw@linux.intel.com
commit 704f3384f322b40ba24d958473edfb1c9750c8fd upstream.
Check carefully on root debugfs available when destroying vgpu, e.g in remove case drm minor's debugfs root might already be destroyed, which led to kernel oops like below.
Console: switching to colour dummy device 80x25 i915 0000:00:02.0: MDEV: Unregistering intel_vgpu_mdev b1338b2d-a709-4c23-b766-cc436c36cdf0: Removing from iommu group 14 BUG: kernel NULL pointer dereference, address: 0000000000000150 PGD 0 P4D 0 Oops: 0000 [#1] PREEMPT SMP CPU: 3 PID: 1046 Comm: driverctl Not tainted 6.1.0-rc2+ #6 Hardware name: HP HP ProDesk 600 G3 MT/829D, BIOS P02 Ver. 02.44 09/13/2022 RIP: 0010:__lock_acquire+0x5e2/0x1f90 Code: 87 ad 09 00 00 39 05 e1 1e cc 02 0f 82 f1 09 00 00 ba 01 00 00 00 48 83 c4 48 89 d0 5b 5d 41 5c 41 5d 41 5e 41 5f c3 45 31 ff <48> 81 3f 60 9e c2 b6 45 0f 45 f8 83 fe 01 0f 87 55 fa ff ff 89 f0 RSP: 0018:ffff9f770274f948 EFLAGS: 00010046 RAX: 0000000000000003 RBX: 0000000000000000 RCX: 0000000000000000 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000150 RBP: 0000000000000000 R08: 0000000000000001 R09: 0000000000000000 R10: ffff8895d1173300 R11: 0000000000000001 R12: 0000000000000000 R13: 0000000000000150 R14: 0000000000000000 R15: 0000000000000000 FS: 00007fc9b2ba0740(0000) GS:ffff889cdfcc0000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000150 CR3: 000000010fd93005 CR4: 00000000003706e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: <TASK> lock_acquire+0xbf/0x2b0 ? simple_recursive_removal+0xa5/0x2b0 ? lock_release+0x13d/0x2d0 down_write+0x2a/0xd0 ? simple_recursive_removal+0xa5/0x2b0 simple_recursive_removal+0xa5/0x2b0 ? start_creating.part.0+0x110/0x110 ? _raw_spin_unlock+0x29/0x40 debugfs_remove+0x40/0x60 intel_gvt_debugfs_remove_vgpu+0x15/0x30 [kvmgt] intel_gvt_destroy_vgpu+0x60/0x100 [kvmgt] intel_vgpu_release_dev+0xe/0x20 [kvmgt] device_release+0x30/0x80 kobject_put+0x79/0x1b0 device_release_driver_internal+0x1b8/0x230 bus_remove_device+0xec/0x160 device_del+0x189/0x400 ? up_write+0x9c/0x1b0 ? mdev_device_remove_common+0x60/0x60 [mdev] mdev_device_remove_common+0x22/0x60 [mdev] mdev_device_remove_cb+0x17/0x20 [mdev] device_for_each_child+0x56/0x80 mdev_unregister_parent+0x5a/0x81 [mdev] intel_gvt_clean_device+0x2d/0xe0 [kvmgt] intel_gvt_driver_remove+0x2e/0xb0 [i915] i915_driver_remove+0xac/0x100 [i915] i915_pci_remove+0x1a/0x30 [i915] pci_device_remove+0x31/0xa0 device_release_driver_internal+0x1b8/0x230 unbind_store+0xd8/0x100 kernfs_fop_write_iter+0x156/0x210 vfs_write+0x236/0x4a0 ksys_write+0x61/0xd0 do_syscall_64+0x55/0x80 ? find_held_lock+0x2b/0x80 ? lock_release+0x13d/0x2d0 ? up_read+0x17/0x20 ? lock_is_held_type+0xe3/0x140 ? asm_exc_page_fault+0x22/0x30 ? lockdep_hardirqs_on+0x7d/0x100 entry_SYSCALL_64_after_hwframe+0x46/0xb0 RIP: 0033:0x7fc9b2c9e0c4 Code: 15 71 7d 0d 00 f7 d8 64 89 02 48 c7 c0 ff ff ff ff eb b7 0f 1f 00 f3 0f 1e fa 80 3d 3d 05 0e 00 00 74 13 b8 01 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 54 c3 0f 1f 00 48 83 ec 28 48 89 54 24 18 48 RSP: 002b:00007ffec29c81c8 EFLAGS: 00000202 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 000000000000000d RCX: 00007fc9b2c9e0c4 RDX: 000000000000000d RSI: 0000559f8b5f48a0 RDI: 0000000000000001 RBP: 0000559f8b5f48a0 R08: 0000559f8b5f3540 R09: 00007fc9b2d76d30 R10: 0000000000000000 R11: 0000000000000202 R12: 000000000000000d R13: 00007fc9b2d77780 R14: 000000000000000d R15: 00007fc9b2d72a00 </TASK> Modules linked in: sunrpc intel_rapl_msr intel_rapl_common intel_pmc_core_pltdrv intel_pmc_core intel_tcc_cooling x86_pkg_temp_thermal intel_powerclamp coretemp kvm_intel ee1004 igbvf rapl vfat fat intel_cstate intel_uncore pktcdvd i2c_i801 pcspkr wmi_bmof i2c_smbus acpi_pad vfio_pci vfio_pci_core vfio_virqfd zram fuse dm_multipath kvmgt mdev vfio_iommu_type1 vfio kvm irqbypass i915 nvme e1000e igb nvme_core crct10dif_pclmul crc32_pclmul crc32c_intel polyval_clmulni polyval_generic serio_raw ghash_clmulni_intel sha512_ssse3 dca drm_buddy intel_gtt video wmi drm_display_helper ttm CR2: 0000000000000150 ---[ end trace 0000000000000000 ]---
Cc: Wang Zhi zhi.a.wang@intel.com Cc: He Yu yu.he@intel.com Cc: Alex Williamson alex.williamson@redhat.com Cc: stable@vger.kernel.org Reviewed-by: Zhi Wang zhi.a.wang@intel.com Tested-by: Yu He yu.he@intel.com Fixes: bc7b0be316ae ("drm/i915/gvt: Add basic debugfs infrastructure") Signed-off-by: Zhenyu Wang zhenyuw@linux.intel.com Link: http://patchwork.freedesktop.org/patch/msgid/20221219140357.769557-2-zhenyuw... Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/gpu/drm/i915/gvt/debugfs.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-)
--- a/drivers/gpu/drm/i915/gvt/debugfs.c +++ b/drivers/gpu/drm/i915/gvt/debugfs.c @@ -175,8 +175,13 @@ void intel_gvt_debugfs_add_vgpu(struct i */ void intel_gvt_debugfs_remove_vgpu(struct intel_vgpu *vgpu) { - debugfs_remove_recursive(vgpu->debugfs); - vgpu->debugfs = NULL; + struct intel_gvt *gvt = vgpu->gvt; + struct drm_minor *minor = gvt->gt->i915->drm.primary; + + if (minor->debugfs_root && gvt->debugfs_root) { + debugfs_remove_recursive(vgpu->debugfs); + vgpu->debugfs = NULL; + } }
/**