Hi,

Well it seemed "like mem leak" but honestly it was my bad assumption i guess.

And does it correlate with io_uring somehow ?

Because i have no such issues when using threads mode in proxmox with network drive that is on fuse.
Could be that triggered perhaps when someone was writing hard to his disk and that would cause other fuse drives to hung for few secs and that would trigger that BUG ?

And using threads somehow fixes that issue ? Does that make any sense ? I am not familiar with low level memory management and io_uring too.

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Tytus Rogalewski

Dolina Krzemowa 6A

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pon., 9 mar 2026 o 21:27 David Hildenbrand (Arm) <david@kernel.org> napisał(a):

On 3/5/26 12:40, David Hildenbrand (Arm) wrote:
> On 3/5/26 12:39, Tytus Rogalewski wrote:
>> I had this problem on 6.19-rc4 yes. I saw it. But i cant reproduce it
>> NOW - this is what i ment :)
>
> Ah, thanks for clarifying, makes sense!
>

The following issue might explain the problem:

https://lore.kernel.org/r/20260309174949.2514565-1-mboone@akamai.com

It would be related to what I recently said: "vfio recently gained
support for installing huge mappings into user page tables."

smaps_walk_ops() does not have a pud_entry() callback, so we'd try to
split (unmap). If that happens concurrently with a refault, we might be
able to trigger a BUG.

But it wouldn't explain any memory leak.

--
Cheers,

David