• Li Ming's avatar
    cxl/mem: Fix no cxl_nvd during pmem region auto-assembling · 84ec9859
    Li Ming authored
    When CXL subsystem is auto-assembling a pmem region during cxl
    endpoint port probing, always hit below calltrace.
    
     BUG: kernel NULL pointer dereference, address: 0000000000000078
     #PF: supervisor read access in kernel mode
     #PF: error_code(0x0000) - not-present page
     RIP: 0010:cxl_pmem_region_probe+0x22e/0x360 [cxl_pmem]
     Call Trace:
      <TASK>
      ? __die+0x24/0x70
      ? page_fault_oops+0x82/0x160
      ? do_user_addr_fault+0x65/0x6b0
      ? exc_page_fault+0x7d/0x170
      ? asm_exc_page_fault+0x26/0x30
      ? cxl_pmem_region_probe+0x22e/0x360 [cxl_pmem]
      ? cxl_pmem_region_probe+0x1ac/0x360 [cxl_pmem]
      cxl_bus_probe+0x1b/0x60 [cxl_core]
      really_probe+0x173/0x410
      ? __pfx___device_attach_driver+0x10/0x10
      __driver_probe_device+0x80/0x170
      driver_probe_device+0x1e/0x90
      __device_attach_driver+0x90/0x120
      bus_for_each_drv+0x84/0xe0
      __device_attach+0xbc/0x1f0
      bus_probe_device+0x90/0xa0
      device_add+0x51c/0x710
      devm_cxl_add_pmem_region+0x1b5/0x380 [cxl_core]
      cxl_bus_probe+0x1b/0x60 [cxl_core]
    
    The cxl_nvd of the memdev needs to be available during the pmem region
    probe. Currently the cxl_nvd is registered after the endpoint port probe.
    The endpoint probe, in the case of autoassembly of regions, can cause a
    pmem region probe requiring the not yet available cxl_nvd. Adjust the
    sequence so this dependency is met.
    
    This requires adding a port parameter to cxl_find_nvdimm_bridge() that
    can be used to query the ancestor root port. The endpoint port is not
    yet available, but will share a common ancestor with its parent, so
    start the query from there instead.
    
    Fixes: f17b558d ("cxl/pmem: Refactor nvdimm device registration, delete the workqueue")
    Co-developed-by: default avatarDan Williams <dan.j.williams@intel.com>
    Signed-off-by: default avatarDan Williams <dan.j.williams@intel.com>
    Signed-off-by: default avatarLi Ming <ming4.li@intel.com>
    Tested-by: default avatarAlison Schofield <alison.schofield@intel.com>
    Reviewed-by: default avatarJonathan Cameron <Jonathan.Cameron@huawei.com>
    Reviewed-by: default avatarAlison Schofield <alison.schofield@intel.com>
    Link: https://patch.msgid.link/20240612064423.2567625-1-ming4.li@intel.comSigned-off-by: default avatarDave Jiang <dave.jiang@intel.com>
    84ec9859
mem.c 6.98 KB