Li Zhijian wrote: > nvdimm_bus_register() could be called from other modules, such as nfit, > but it can only be called after the nvdimm_bus_type is registered. > > BUG: kernel NULL pointer dereference, address: 0000000000000098 > #PF: supervisor read access in kernel mode > #PF: error_code(0x0000) - not-present page > PGD 0 P4D 0 > Oops: 0000 [#1] PREEMPT SMP PTI > CPU: 0 PID: 117 Comm: systemd-udevd Not tainted 6.2.0-rc6-pmem+ #97 > Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS > rel-1.16.0-0-gd239552ce722-prebuilt.qemu.org 04/01/2014 > RIP: 0010:bus_add_device+0x58/0x150 > Call Trace: > <TASK> > device_add+0x3ac/0x980 > nvdimm_bus_register+0x16d/0x1d0 > acpi_nfit_init+0xb72/0x1f90 [nfit] > acpi_nfit_add+0x1d5/0x200 [nfit] > acpi_device_probe+0x45/0x160
Can you explain a bit more how to hit this crash? This has not been a problem historically and the explanation above makes it sound like this is a theoretical issue. libnvdimm_init() *should* be done before the nfit driver can attempt nvdimm_bus_register(). So, something else is broken if nvdimm_bus_register() can be called before libnvdimm_init(), or after libnvdimm_exit().
