Re: [PATCH v2 2/4] cxl/memdev: Hold memdev lock during memdev poison injection/clear

[Li Ming <ming.li@zohomail.com>]

在 2026/4/12 03:23, Dan Williams 写道:
> Dave Jiang wrote:
>>
>> On 3/18/26 4:59 AM, Li Ming wrote:
>>> 在 2026/3/17 23:00, Dave Jiang 写道:
>>>> On 3/14/26 12:06 AM, Li Ming wrote:
>>>>> CXL memdev poison injection/clearing debugfs interfaces are visible
>>>>> before the CXL memdev endpoint initialization, If user accesses the
>>>>> interfaces before cxlmd->endpoint updated, it is possible to access an
>>>>> invalid endpoint in cxl_dpa_to_region().
>>>>>
>>>>> Hold CXL memdev lock at the beginning of the interfaces, this blocks the
>>>>> interfaces until CXL memdev probing completed.
>>>>>
>>>>> The following patch will check the given endpoint validity in
>>>>> cxl_dpa_to_region().
>>>>>
>>>>> Suggested-by: Dan Williams <dan.j.williams@intel.com>
>>>>> Reviewed-by: Dave Jiang <dave.jiang@intel.com>
>>>>> Reviewed-by: Alison Schofield <alison.schofield@intel.com>
>>>>> Signed-off-by: Li Ming <ming.li@zohomail.com>
>>>> Hi Ming, I dropped this patch with Dan's comments [1] and updated cxl/next. Please check and make sure everything looks ok to you. Thanks!
>>>>
>>>> [1]: https://lore.kernel.org/linux-cxl/69b8b81621e16_452b100e@dwillia2-mobl4.notmuch/
>>> Hi Dave,
>>>
>>> I think there is no change needed in this patch, just need a independent patch for holding memdev lock in cxl_region_debugfs_poison_inject/clear.
>>>
>>> Or you want to review this patch again?
>> No. Maybe I misunderstood the comment from Dan. So we should keep this patch?
> tl;dr: yes, this patch is *now* valid.
>
> As originally structured having patch2 before patch3 added no value.
> Going forward I would say do not structure a series such that a new lock
> taken in patch N starts being useful in patch N+1.
>
> I assume that is what:
>
> "The following patch will check the given endpoint validity in
> cxl_dpa_to_region()."
>
> ...is trying to say, but when commits are applied to the tree it is
> difficult to see that this commit was from a series.
>
> So do pick this one up, but the changelog needs adjusting. Something
> like:
>
> "cxl_dpa_to_region() assumes that it is running a context where it is not
> racing changes to "cxlmd->dev.driver". Acquire the memdev device lock in
> the debugfs entry points to preclude debugfs usage racing cxl_mem driver
> detach."
>
> With that you can add:
>
> Reviewed-by: Dan Williams <djbw@kernel.org>

Hi Dave,

Will you pick this patch with changes from Dan's comment? Or I need to 
send out a new version?


Ming