<!DOCTYPE html><html><head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8"> </head> <body> <div class="moz-cite-prefix">On 1/1/2025 11:36 PM, Jiang Liu wrote: </div> <blockquote type="cite" cite="mid:176921ed3539fb55e4a222212b638caf84ebf4aa.1735795671.git.gerry@linux.alibaba.com"> <pre wrap="" class="moz-quote-pre">If some GPU device failed to probe, `rmmod amdgpu` will trigger a use after free bug related to amdgpu_driver_release_kms() as: 2024-12-26 16:17:45 [16002.085540] BUG: kernel NULL pointer dereference, address: 0000000000000000 2024-12-26 16:17:45 [16002.093792] #PF: supervisor read access in kernel mode 2024-12-26 16:17:45 [16002.099993] #PF: error_code(0x0000) - not-present page 2024-12-26 16:17:45 [16002.106188] PGD 0 P4D 0 2024-12-26 16:17:45 [16002.109464] Oops: Oops: 0000 [#1] PREEMPT SMP NOPTI 2024-12-26 16:17:45 [16002.115372] CPU: 2 PID: 14375 Comm: rmmod Kdump: loaded Tainted: G W E 6.10.0+ #2 2024-12-26 16:17:45 [16002.125577] Hardware name: Alibaba Alibaba Cloud ECS/Alibaba Cloud ECS, BIOS 3.0.ES.AL.P.087.05 04/07/2024 2024-12-26 16:17:45 [16002.136858] RIP: 0010:drm_sched_fini+0x3f/0xe0 [gpu_sched] 2024-12-26 16:17:45 [16002.143463] Code: 60 c6 87 be 00 00 00 01 e8 ce e0 90 d8 48 8d bb 80 00 00 00 e8 c2 e0 90 d8 8b 43 20 85 c0 74 51 45 31 e4 48 8b 43 28 4d 63 ec <4a> 8b 2c e8 48 89 ef e8 f5 0e 59 d9 48 8b 45 10 48 8d 55 10 48 39 2024-12-26 16:17:45 [16002.164992] RSP: 0018:ffffb570dbbb7da8 EFLAGS: 00010246 2024-12-26 16:17:45 [16002.171316] RAX: 0000000000000000 RBX: ffff96b0fdadc878 RCX: 0000000000000000 2024-12-26 16:17:46 [16002.179784] RDX: 000fffffffe00000 RSI: 0000000000000000 RDI: ffff96b0fdadc8f8 2024-12-26 16:17:46 [16002.188252] RBP: ffff96b0fdadc800 R08: ffff97abbd035040 R09: ffffffff9ac52540 2024-12-26 16:17:46 [16002.196722] R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 2024-12-26 16:17:46 [16002.205179] R13: 0000000000000000 R14: ffff96b0fdadfc00 R15: 0000000000000000 2024-12-26 16:17:46 [16002.213648] FS: 00007f2737000740(0000) GS:ffff97abbd100000(0000) knlGS:0000000000000000 2024-12-26 16:17:46 [16002.223189] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 2024-12-26 16:17:46 [16002.230103] CR2: 0000000000000000 CR3: 000000011be3a005 CR4: 0000000000f70ef0 2024-12-26 16:17:46 [16002.238581] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 2024-12-26 16:17:46 [16002.247053] DR3: 0000000000000000 DR6: 00000000fffe07f0 DR7: 0000000000000400 e024se+0x3c/0x90 [amdxcp] 2024-12-26 16:17:46 [16002.337645] __do_sys_delete_module.constprop.0+0x176/0x310 2024-12-26 16:17:46 [16002.344324] do_syscall_64+0x5d/0x170 2024-12-26 16:17:46 [16002.348858] entry_SYSCALL_64_after_hwframe+0x76/0x7e 2024-12-26 16:17:46 [16002.354956] RIP: 0033:0x7f2736a620cb-12-26 Fix it by unplugging xcp drm devices when failed to probe GPU devices. Signed-off-by: Jiang Liu <a class="moz-txt-link-rfc2396E" href="mailto:gerry@linux.alibaba.com"><gerry@linux.alibaba.com></a> Tested-by: Shuo Liu <a class="moz-txt-link-rfc2396E" href="mailto:shuox.liu@linux.alibaba.com"><shuox.liu@linux.alibaba.com></a> --- drivers/gpu/drm/amd/amdgpu/amdgpu_kms.c | 4 +++- drivers/gpu/drm/amd/amdgpu/amdgpu_xcp.c | 1 + 2 files changed, 4 insertions(+), 1 deletion(-) diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_kms.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_kms.c index 5ffe1dad9622..e7f35e3a6d2d 100644 --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_kms.c +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_kms.c @@ -164,8 +164,10 @@ int amdgpu_driver_load_kms(struct amdgpu_device *adev, unsigned long flags) DRM_WARN("smart shift update failed\n"); out: - if (r) + if (r) { + amdgpu_xcp_dev_unplug(adev); amdgpu_driver_unload_kms(dev); + } </pre> </blockquote> I wonder if you can call amdgpu_xcp_dev_unplug here. It will call drm_dev_unplug that unplugs a hotpluggable DRM device. In you case amdgpu_driver_load_kms failed during probe time. We need unwind amdgpu_driver_load_kms. Why need do unplug a DRM device? The backtrace show: <pre wrap="" class="moz-quote-pre">2024-12-26 16:17:45 [16002.136858] RIP: 0010:drm_sched_fini+0x3f/0xe0 [gpu_sched]</pre> has: <pre wrap="" class="moz-quote-pre">2024-12-26 16:17:45 [16002.085540] BUG: kernel NULL pointer dereference, address: 0000000000000000</pre> How this change is related to the invalid access above? Can you explain more? Regards Xiaogang <blockquote type="cite" cite="mid:176921ed3539fb55e4a222212b638caf84ebf4aa.1735795671.git.gerry@linux.alibaba.com"> <pre wrap="" class="moz-quote-pre"> return r; } diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_xcp.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_xcp.c index a6d456ec6aeb..ef4eaacf67f6 100644 --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_xcp.c +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_xcp.c @@ -382,6 +382,7 @@ void amdgpu_xcp_dev_unplug(struct amdgpu_device *adev) p_ddev->primary->dev = adev->xcp_mgr->xcp[i].pdev; p_ddev->driver = adev->xcp_mgr->xcp[i].driver; p_ddev->vma_offset_manager = adev->xcp_mgr->xcp[i].vma_offset_manager; + adev->xcp_mgr->xcp[i].ddev = NULL; } } </pre> </blockquote> </body> </html>