On Sun, 22 Mar 2026 19:53:41 +0000 Smita Koralahalli <[email protected]> wrote:
> The current probe time ownership check for Soft Reserved memory based > solely on CXL window intersection is insufficient. dax_hmem probing is not > always guaranteed to run after CXL enumeration and region assembly, which > can lead to incorrect ownership decisions before the CXL stack has > finished publishing windows and assembling committed regions. > > Introduce deferred ownership handling for Soft Reserved ranges that > intersect CXL windows. When such a range is encountered during the > initial dax_hmem probe, schedule deferred work to wait for the CXL stack > to complete enumeration and region assembly before deciding ownership. > > Once the deferred work runs, evaluate each Soft Reserved range > individually: if a CXL region fully contains the range, skip it and let > dax_cxl bind. Otherwise, register it with dax_hmem. This per-range > ownership model avoids the need for CXL region teardown and > alloc_dax_region() resource exclusion prevents double claiming. > > Introduce a boolean flag dax_hmem_initial_probe to live inside device.c > so it survives module reload. Ensure dax_cxl defers driver registration > until dax_hmem has completed ownership resolution. dax_cxl calls > dax_hmem_flush_work() before cxl_driver_register(), which both waits for > the deferred work to complete and creates a module symbol dependency that > forces dax_hmem.ko to load before dax_cxl. > > Co-developed-by: Dan Williams <[email protected]> > Signed-off-by: Dan Williams <[email protected]> > Signed-off-by: Smita Koralahalli <[email protected]> Reviewed-by: Jonathan Cameron <[email protected]>
