Re: [PATCH v3 0/9] x86,fs/resctrl: Fix long-standing issues

[Reinette Chatre]

Hi Tony,

On 5/28/26 1:08 PM, Luck, Tony wrote:
> On Fri, May 22, 2026 at 12:15:04PM -0700, Reinette Chatre wrote:
>> v2: https://lore.kernel.org/lkml/20260515193944.15114-1-tony.luck@xxxxxxxxx/
>> v1: https://lore.kernel.org/all/20260508182143.14592-1-tony.luck@xxxxxxxxx/
>>
>> While reviewing the AET series [1] Sashiko reported a deadlock during mount,
>> and a use-after-free when an L3 domain is removed during CPU offline. Reinette
>> found a memory leak in the mount error path while refactoring code for a
>> solution to the mount hang.
>>
>> During review of V1 of this series Sashiko found a new UAF on unmount issue
>> that was fixed in V2.
>>
>> During review of V2 Sashiko uncovered a couple more new issues: TOCTOU
>> involving rdtgroup_kn_put() that may lead to UAF or double-free, double
>> free of pseudo-locked regions, potential deadlock between resctrl unmount and
>> info file readers. Sashiko also found that the CPU offline fix in V2 is flawed
>> in its use of is_percpu_thread().
>>
>> Address all issues identified. This version is significantly different from V2
>> because of the additional fixes and reworking of the CPU offline fix. I do not
>> consider this version quite "polished" but after all changes made to address
>> all the issues identified by Sashiko I would like to check-in with folks (and
>> Sashiko) on where the fixes are headed and would appreciate any feedback.
> 
> Several of these patches are either authored or co-authored by me, so
> I'm uncertain about the ethics of piling on a Reviewed-by tag.
> 
> Apart from patch 6 to fix sashiko reported issues in pseudo-locking
> everything looks good. I agree with Reinette's assessment[1] that
> pursuing the bizarre corner case races for pseudo-locking should
> not be a priority. That patch can be dropped.

Thank you for taking a look. 

After thinking about patch 6 more I plan to drop the fixes surrounding the races
but keep the fix for the RMID double-add. Since this will touch pseudo-locking region
lifetime management I expect Sashiko would bring up the pseudo-locking races
during its review but I believe this is a worthy fix.

As a summary of your tags for this series I see:
- patches 1, 2, 3, 4, and 9 have your Signed-off-by.
- patches 5, 7, and 8 do not have any tags from you.

Reinette