On 17/03/2023 10:26, Dan Williams wrote: > 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.
That would be great. > Apologies for missing it earlier. Never mind :) > > 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. sounds good, i will update it in next version. Thanks Zhijian
