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From: Dan Williams <dan.j.williams@intel.com>
To: Li Zhijian <lizhijian@fujitsu.com>, <dan.j.williams@intel.com>,
	<vishal.l.verma@intel.com>, <dave.jiang@intel.com>,
	<ira.weiny@intel.com>, <nvdimm@lists.linux.dev>
Cc: <linux-kernel@vger.kernel.org>, Li Zhijian <lizhijian@fujitsu.com>
Subject: RE: [PATCH] nvdimm: nvdimm_bus_register: Avoid adding device to the unregistered bus
Date: Thu, 16 Mar 2023 08:54:51 -0700	[thread overview]
Message-ID: <64133bcbbe368_269929415@dwillia2-xfh.jf.intel.com.notmuch> (raw)
In-Reply-To: <1678955931-2-1-git-send-email-lizhijian@fujitsu.com>

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().

  reply	other threads:[~2023-03-16 15:55 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-03-16  8:38 Li Zhijian
2023-03-16 15:54 ` Dan Williams [this message]
2023-03-17  1:42   ` lizhijian
2023-03-17  2:26     ` Dan Williams
2023-03-17  5:37       ` lizhijian
2023-03-17  5:59     ` Dan Williams
2023-03-20  2:06       ` lizhijian
2023-03-20 17:30         ` Dan Williams
2023-03-21  2:17           ` lizhijian
2023-03-21  2:38             ` Dan Williams
2023-03-21  3:19               ` lizhijian

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