From 19398821b25a9cde564265262e680ae1c2351be7 Mon Sep 17 00:00:00 2001 From: Dan Williams Date: Fri, 20 Jan 2023 16:26:12 -0800 Subject: cxl/pmem: Fix nvdimm unregistration when cxl_pmem driver is absent The cxl_pmem.ko module houses the driver for both cxl_nvdimm_bridge objects and cxl_nvdimm objects. When the core creates a cxl_nvdimm it arranges for it to be autoremoved when the bridge goes down. However, if the bridge never initialized because the cxl_pmem.ko module never loaded, it sets up a the following crash scenario: BUG: kernel NULL pointer dereference, address: 0000000000000478 [..] RIP: 0010:cxl_nvdimm_probe+0x99/0x140 [cxl_pmem] [..] Call Trace: cxl_bus_probe+0x17/0x50 [cxl_core] really_probe+0xde/0x380 __driver_probe_device+0x78/0x170 driver_probe_device+0x1f/0x90 __driver_attach+0xd2/0x1c0 bus_for_each_dev+0x79/0xc0 bus_add_driver+0x1b1/0x200 driver_register+0x89/0xe0 cxl_pmem_init+0x50/0xff0 [cxl_pmem] It turns out the recent rework to simplify nvdimm probing obviated the need to unregister cxl_nvdimm objects at cxl_nvdimm_bridge ->remove() time. Leave the cxl_nvdimm device registered until the hosting cxl_memdev departs. The alternative is that the cxl_memdev needs to be reattached whenever the cxl_nvdimm_bridge attach state cycles, which is awkward and unnecessary. The only requirement is to make sure that when the cxl_nvdimm_bridge goes away any dependent cxl_nvdimm objects are shutdown. Handle that in unregister_nvdimm_bus(). With these registration entanglements removed there is no longer a need to pre-load the cxl_pmem module in cxl_acpi. Fixes: cb9cfff82f6a ("cxl/acpi: Simplify cxl_nvdimm_bridge probing") Reported-by: Gregory Price Debugged-by: Jonathan Cameron Tested-by: Jonathan Cameron Reviewed-by: Jonathan Cameron Reviewed-by: Dave Jiang Link: https://lore.kernel.org/r/167426077263.3955046.9695309346988027311.stgit@dwillia2-xfh.jf.intel.com Signed-off-by: Dan Williams --- drivers/cxl/acpi.c | 1 - 1 file changed, 1 deletion(-) (limited to 'drivers/cxl/acpi.c') diff --git a/drivers/cxl/acpi.c b/drivers/cxl/acpi.c index ad0849af42d7..13cde44c6086 100644 --- a/drivers/cxl/acpi.c +++ b/drivers/cxl/acpi.c @@ -736,4 +736,3 @@ module_exit(cxl_acpi_exit); MODULE_LICENSE("GPL v2"); MODULE_IMPORT_NS(CXL); MODULE_IMPORT_NS(ACPI); -MODULE_SOFTDEP("pre: cxl_pmem"); -- cgit v1.2.3