Re: [PATCH v2 0/4] mm/hmm: Clarify notifier retry state and scope HMM timeouts

[David Hildenbrand (Arm)]

On 7/15/26 00:21, Stanislav Kinsburskii wrote:
> This small fixup series applies on top of:
> 
>   [PATCH v8 0/8] mm/hmm: Add mmap lock-drop support for userfaultfd-backed mappings
> 
> The first patch updates the HMM documentation example to make the
> mmu_interval_read_retry() state explicit: callers should use the notifier and
> notifier_seq stored in the same hmm_range that was passed to
> hmm_range_fault_unlocked_timeout().
> 
> The remaining patches adjust nouveau, amdxdna, and drm_gpusvm users so the
> timeout passed to hmm_range_fault_unlocked_timeout() is treated as a relative
> HMM retry budget. These callers no longer keep an absolute deadline around
> their outer driver retry loops or pass a computed remaining time into HMM.
> 
> This keeps the timeout scoped to HMM's internal mmu-notifier retry handling. If
> HMM succeeds and the driver later observes an invalidation through
> mmu_interval_read_retry(), the driver retries the operation with a fresh HMM
> retry budget.
> 
> Changes in v2:
>   - Kept the nouveau outer absolute timeout around the
>     mmu_interval_read_retry() loop. hmm_range_fault_unlocked_timeout() only
>     bounds HMM’s internal retries, while nouveau faults are handled from a GPU
>     fault worker, so userspace fatal signals cannot break an endless stream of
>     invalidations there.
>   - Updated nouveau to use time_after_eq() before calling HMM, so the remaining
>     timeout passed to hmm_range_fault_unlocked_timeout() is always positive and
>     never 0, which would mean retry indefinitely.
>   - Updated the nouveau fixup commit message to explain the worker-thread
>     timeout issue and the time_after_eq() boundary behavior.
>   - Fixed the amdxdna fixup commit message. It now describes
>     aie2_populate_range() correctly instead of carrying stale nouveau prose,
>     and notes that command submission still keeps its broader timeout while HMM
>     gets a fresh relative retry budget.
> 
> 
> ---
> 
> Stanislav Kinsburskii (4):
>       fixup! mm/hmm: add hmm_range_fault_unlocked_timeout() for mmap lock-drop support
>       fixup! drm/nouveau: use hmm_range_fault_unlocked_timeout() for SVM faults
>       fixup! accel/amdxdna: use hmm_range_fault_unlocked_timeout() for range population
>       fixup! drm/gpusvm: use hmm_range_fault_unlocked_timeout() for range faults

Why a fixup series instead of properly resending the full thing?

-- 
Cheers,

David