Re: [PATCH v1 01/31] x86/resctrl: Fix allocation of cleanest CLOSID on platforms with no monitors

Reinette Chatre
2024-04-09T15:02:40Z

Hi David,

(Thank you very much for taking a look at these)

On 4/9/2024 1:05 AM, David Hildenbrand wrote:
> On 21.03.24 17:50, James Morse wrote:
>> commit 6eac36bb9eb0 ("x86/resctrl: Allocate the cleanest CLOSID by
>> searching closid_num_dirty_rmid") added a Kconfig option that causes
>> resctrl to search for the CLOSID with the fewest dirty cache lines when
>> creating a new control group. This depends on the values read from the
>> llc_occupancy counters.
>>
>> This support missed that some platforms may not have these counters.
>> This causes a NULL pointer dereference when creating a new control
>> group as the array was not allocated by dom_data_init().
>>
>> As this feature isn't necessary on platforms that don't have cache
>> occupancy monitors, add this to the check that occurs when a new
>> control group is allocated.
>>
>> The existing code is not selected by any upstream platform, it makes
>> no sense to backport this patch to stable.
>>
>
> It's weird to not see RESCTRL_RMID_DEPENDS_ON_CLOSID appear in any Kconfig file.
> I guess it will all make sense once the refactoring is done :)

This is done later in this series where patch #29, "fs/resctrl: Add boiler
plate for external resctrl code", introduces it to fs/resctrl/Kconfig.

Reinette