lizhij...@fujitsu.com wrote: > > > On 16/03/2023 23:54, Dan Williams wrote: > > 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. > > > > Dan, > > Configure the kconfig with ACPI_NFIT [=m] && LIBNVDIMM [=y], and add extra > kernel booting parameter > 'initcall_blacklist=libnvdimm_init'. Then kernel panic! > Theoretically, it will also happen if nvdimm_bus_register() failed. > > > For kdump purpose[1], we need to disable libnvdimm driver to ensure metadata > in pmem will not be updated again in kdump kernel > [1]https://lore.kernel.org/linux-mm/3c752fc2-b6a0-2975-ffec-dba3edcf4...@fujitsu.com/T/
Ah, great write up! Let me give that some thought. Apologies for missing it earlier. This would have been a good use for: Link: https://lore.kernel.org/linux-mm/3c752fc2-b6a0-2975-ffec-dba3edcf4...@fujitsu.com ...in the above changelog.
