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The `ttm_resource_manager_usage()` function currently assumes `man->bdev` is non-NULL when accessing `man->bdev->lru_lock`. However, in scenarios where the resource manager is not fully initialized (e.g., APU platforms that lack dedicated VRAM, or incomplete manager setup), `man->bdev` may remain NULL. This leads to a NULL pointer dereference when attempting to acquire the `lru_lock`, triggering kernel OOPS. Fix this by adding an explicit safety check for `man->bdev` before accessing its members: - Use `WARN_ON_ONCE(!man->bdev)` to emit a one-time warning (a soft assertion) when `man->bdev` is NULL. This helps catch invalid usage patterns during debugging without breaking production workflows. - Return 0 immediately if `man->bdev` is NULL, as a non-initialized manager cannot have valid resource usage to report. Suggested-by: Christian König <christian.koenig@amd.com> Suggested-by: Lijo Lazar <lijo.lazar@amd.com> Signed-off-by: Jesse Zhang <jesse.zhang@amd.com> Reviewed-by: Christian König <christian.koenig@amd.com> Signed-off-by: Arunpravin Paneer Selvam <Arunpravin.PaneerSelvam@amd.com> Link: https://lore.kernel.org/r/20251013085849.1735612-1-Jesse.Zhang@amd.com
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.