Re: [PATCH v5 6/7] drm/xe: Reject vm_ops->access on BO mappings of an unplugged device

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential
issue to consider:
- [Low] drm/xe: missing Fixes trailer in commit fixing xe_bo_vm_access()
  unplug check
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commit 2c50602f8cb3fdeed79be6d7644c7fd302b6e48d
Author: Umesh Nerlige Ramappa <umesh.nerlige.ramappa@intel.com>

> drm/xe: Reject vm_ops->access on BO mappings of an unplugged device
>
> A userspace mapping of a BO can outlive the device, e.g. across unbind
> or a PCI slot reset. After drm_dev_unplug() the fault handler only
> installs a dummy page, but ptrace, /proc/<pid>/mem and
> process_vm_readv() can't use get_user_pages() on these VM_PFNMAP vmas
> and fall back to vm_ops->access(), i.e. xe_bo_vm_access().
>
> xe_bo_vm_access() doesn't check whether the device is still there. For
> a BO in VRAM, xe_ttm_access_memory() then either goes through the VRAM
> iomap, which is unmapped on remove, or submits a migrate job after the
> GT has been torn down. This applies to GEM mmaps and to the OA buffer
> mmap of an OA stream that outlives the device.
>
> Enter a drm_dev_enter() section in xe_bo_vm_access() and fail with
> -ENODEV once the device is unplugged, like xe_bo_cpu_fault() does.
>
> Signed-off-by: Umesh Nerlige Ramappa <umesh.nerlige.ramappa@intel.com>
> Cc: Matthew Brost <matthew.brost@intel.com>

[Severity: Low]
Since this fixes a missing unplug check in xe_bo_vm_access(), should the
commit message include:

  Fixes: f85dc3c5abdd ("drm/xe: Add xe_bo_vm_access")

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Sashiko AI review · https://sashiko.dev/#/patchset/20261110190052.3514226-9-umesh.nerlige.ramappa@intel.com?part=6