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Doing devcoredump initializing before GT though look harmless, it leads to problem during driver unbind. Because of this order, GT/Engine release functions will be called before xe devcoredump release function (xe_driver_devcoredump_fini) leading to the following kernel crash[1] because the devcoredump functions might still use GT/Engine datastructures after those are freed. The following crash is observed while running the IGT xe_wedged@wedged-at-any-timeout. The test forces a wedged state by submitting a workload which hangs. Then does a unbind/rebind of the driver to recover from the wedged state. The hanged workload leads to a devcoredump. The following crash is noticed when the devcoredump capture races with the driver unbind. During driver unbind, the release function hw_engine_fini() will be called which assigns NULL to hwe->gt. But the same data structure is accessed during the coredump capture in the function xe_engine_snapshot_print by reading snapshot->hwe->gt. With this patch, we make sure the devcoredump is stopped before deinitializing the core driver functions. [1]: BUG: kernel NULL pointer dereference, address: 0000000000000000 Workqueue: events_unbound xe_devcoredump_deferred_snap_work [xe] RIP: 0010:xe_engine_snapshot_print+0x47/0x420 [xe] Call Trace: <TASK> ? drm_printf+0x64/0x90 __xe_devcoredump_read+0x23f/0x2d0 [xe] ? __pfx___drm_printfn_coredump+0x10/0x10 ? __pfx___drm_puts_coredump+0x10/0x10 xe_devcoredump_deferred_snap_work+0x17a/0x190 [xe] process_one_work+0x22e/0x6f0 worker_thread+0x1e8/0x3d0 ? __pfx_worker_thread+0x10/0x10 kthread+0x11f/0x250 ? __pfx_kthread+0x10/0x10 ret_from_fork+0x47/0x70 ? __pfx_kthread+0x10/0x10 ret_from_fork_asm+0x1a/0x30 v2: Detailed commit description (Rodrigo) v3: FIXME added (Rodrigo, Stuart) Fixes:4209d635a8("drm/xe: Remove devcoredump during driver release") Reviewed-by: Stuart Summers <stuart.summers@intel.com> Link: https://lore.kernel.org/r/20250731061300.14320-1-balasubramani.vivekanandan@intel.com Signed-off-by: Balasubramani Vivekanandan <balasubramani.vivekanandan@intel.com> Link: https://lore.kernel.org/r/20250801052356.21885-1-balasubramani.vivekanandan@intel.com Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com> (cherry picked from commit1fdc4c381f) Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.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.