drm_suballoc_new() currently both allocates the SA object using kmalloc()
and searches for a suitable hole in the sub-allocator for the requested
size. If SA allocation is done by holding sub-allocator mutex, this design
can lead to reclaim safety issues.
By splitting the kmalloc() step outside of the critical section, we allow
the memory allocation to use GFP_KERNEL (reclaim-safe) while ensuring that
the initialization step that holds reclaim-tainted locks (sub-allocator
mutex) operates in a reclaim-unsafe context with pre-allocated memory.
This separation prevents potential deadlocks where memory reclaim could
attempt to acquire locks that are already held during the sub-allocator
operations.
Signed-off-by: Satyanarayana K V P <[email protected]>
Suggested-by: Matthew Brost <[email protected]>
Cc: Thomas Hellström <[email protected]>
Cc: Michal Wajdeczko <[email protected]>
Cc: Matthew Auld <[email protected]>
Cc: Christian König <[email protected]>
Cc: [email protected]
Cc: Maarten Lankhorst <[email protected]>
Reviewed-by: Christian König <[email protected]>
Reviewed-by: Thomas Hellström <[email protected]>
Reviewed-by: Matthew Brost <[email protected]>
Acked-by: Maarten Lankhorst <[email protected]>
Signed-off-by: Matthew Brost <[email protected]>
Link: https://patch.msgid.link/[email protected]
Suballocating a buffer object is something that is not driver-specific
and useful for many drivers.
Use a slightly modified version of amdgpu_sa.c
v2:
- Style cleanups.
- Added / Modified documentation.
- Use u64 for the sizes and offset. The code dates back to 2012 and
using unsigned int will probably soon come back to bite us.
We can consider size_t as well for better 32-bit efficiency.
- Add and document gfp, intr and align arguments to drm_suballoc_new().
- Use drm_printer for debug output.
v3:
- Remove stale author info (Christian König)
v4:
- Avoid 64-bit integer divisions (kernel test robot <[email protected]>)
- Use size_t rather than u64 for the managed range. (Thomas)
Signed-off-by: Maarten Lankhorst <[email protected]>
Co-developed-by: Thomas Hellström <[email protected]>
Signed-off-by: Thomas Hellström <[email protected]>
Reviewed-by: Christian König <[email protected]>
Acked-by: Maarten Lankhorst <[email protected]>
Acked-by: Alex Deucher <[email protected]>
Acked-by: Christian König <[email protected]>
Link: https://patchwork.freedesktop.org/patch/msgid/[email protected]
Satyanarayana K V P