Re: [Intel-wired-lan] Increased memory usage on NUMA nodes with ICE driver after upgrade to 6.13.y (regression in commit 492a044508ad)

[Jacob Keller <jacob.e.keller@intel.com>]

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On 7/8/2025 5:50 PM, Jacob Keller wrote:
> 
> 
> On 7/7/2025 3:03 PM, Jacob Keller wrote:
>> Bad news: my hypothesis was incorrect.
>>
>> Good news: I can immediately see the problem if I set MTU to 9K and
>> start an iperf3 session and just watch the count of allocations from
>> ice_alloc_mapped_pages(). It goes up consistently, so I can quickly tell
>> if a change is helping.
>>
>> I ported the stats from i40e for tracking the page allocations, and I
>> can see that we're allocating new pages despite not actually performing
>> releases.
>>
>> I don't yet have a good understanding of what causes this, and the logic
>> in ice is pretty hard to track...
>>
>> I'm going to try the page pool patches myself to see if this test bed
>> triggers the same problems. Unfortunately I think I need someone else
>> with more experience with the hotpath code to help figure out whats
>> going wrong here...
> 
> I believe I have isolated this and figured out the issue: With 9K MTU,
> sometimes the hardware posts a multi-buffer frame with an extra
> descriptor that has a size of 0 bytes with no data in it. When this
> happens, our logic for tracking buffers fails to free this buffer. We
> then later overwrite the page because we failed to either free or re-use
> the page, and our overwriting logic doesn't verify this.
> 
> I will have a fix with a more detailed description posted tomorrow.

@Jaroslav, I've posted a fix which I believe should resolve your issue:

https://lore.kernel.org/intel-wired-lan/20250709-jk-ice-fix-rx-mem-leak-v1-1-cfdd7eeea905@intel.com/T/#u

I am reasonably confident it should resolve the issue you reported. If
possible, it would be appreciated if you could test it and report back
to confirm.

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