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

[Stanislav Kinsburskii]

On Wed, Jul 15, 2026 at 05:02:59PM +0100, Lorenzo Stoakes (ARM) wrote:
> To avoid confusion: obviously please don't merge this series Andrew.
> 
> On Wed, Jul 15, 2026 at 07:42:48AM -0700, Stanislav Kinsburskii wrote:
> > On Wed, Jul 15, 2026 at 02:41:43PM +0200, David Hildenbrand (Arm) wrote:
> > > 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?
> > >
> >
> > The goal was to get a Sashiko review, and v8 has already been applied to
> > both `mm-new` and `linux-next`.
> 
> Please don't do this, this is completely impossible to track for review :)
> 
> mm review is currently very difficult based on volumes, it'll become impossible
> to manage if people sound fragments of series.
> 
> Please just resend the whole thing at this point.
> 

Well, I followed the guidance provided by Andrew, and I believe he
applied all of the changes, including these, to the `mm` tree.

Do you still want me to send v9 under these circumstances?

Thanks, Stanislav

> >
> > You can find more details here:
> >
> >   https://sashiko.dev/#/message/alaWmUEeIBeSkmO0%40skinsburskii
> >
> > Thanks, Stanislav
> >
> > > --
> > > Cheers,
> > >
> > > David
> 
> Thanks, Lorenzo