From 350b2f2b1f2af93581008b9d0e4ab4a8af84b379 Mon Sep 17 00:00:00 2001 From: Philip Yang Date: Thu, 29 Jul 2021 17:19:54 -0400 Subject: [PATCH] drm/amdgpu: fix fdinfo race with process exit [ Upstream commit d7eff46c214c036606dd3cd305bd5a128aecfe8c ] Get process vm root BO ref in case process is exiting and root BO is freed, to avoid NULL pointer dereference backtrace: BUG: unable to handle kernel NULL pointer dereference at 0000000000000000 Call Trace: amdgpu_show_fdinfo+0xfe/0x2a0 [amdgpu] seq_show+0x12c/0x180 seq_read+0x153/0x410 vfs_read+0x91/0x140[ 3427.206183] ksys_read+0x4f/0xb0 do_syscall_64+0x5b/0x1a0 entry_SYSCALL_64_after_hwframe+0x65/0xca Signed-off-by: Philip Yang Reviewed-by: Felix Kuehling Signed-off-by: Alex Deucher Signed-off-by: Sasha Levin --- drivers/gpu/drm/amd/amdgpu/amdgpu_fdinfo.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_fdinfo.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_fdinfo.c index d94c5419ec25c..5a6857c44bb66 100644 --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_fdinfo.c +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_fdinfo.c @@ -59,6 +59,7 @@ void amdgpu_show_fdinfo(struct seq_file *m, struct file *f) uint64_t vram_mem = 0, gtt_mem = 0, cpu_mem = 0; struct drm_file *file = f->private_data; struct amdgpu_device *adev = drm_to_adev(file->minor->dev); + struct amdgpu_bo *root; int ret; ret = amdgpu_file_to_fpriv(f, &fpriv); @@ -69,13 +70,19 @@ void amdgpu_show_fdinfo(struct seq_file *m, struct file *f) dev = PCI_SLOT(adev->pdev->devfn); fn = PCI_FUNC(adev->pdev->devfn); - ret = amdgpu_bo_reserve(fpriv->vm.root.bo, false); + root = amdgpu_bo_ref(fpriv->vm.root.bo); + if (!root) + return; + + ret = amdgpu_bo_reserve(root, false); if (ret) { DRM_ERROR("Fail to reserve bo\n"); return; } amdgpu_vm_get_memory(&fpriv->vm, &vram_mem, >t_mem, &cpu_mem); - amdgpu_bo_unreserve(fpriv->vm.root.bo); + amdgpu_bo_unreserve(root); + amdgpu_bo_unref(&root); + seq_printf(m, "pdev:\t%04x:%02x:%02x.%d\npasid:\t%u\n", domain, bus, dev, fn, fpriv->vm.pasid); seq_printf(m, "vram mem:\t%llu kB\n", vram_mem/1024UL);