+ drm-nouveau-use-hmm_range_fault_unlocked_timeout-for-svm-faults.patch added to mm-unstable branch

The patch titled
     Subject: drm/nouveau: use hmm_range_fault_unlocked_timeout() for SVM faults
has been added to the -mm mm-unstable branch.  Its filename is
     drm-nouveau-use-hmm_range_fault_unlocked_timeout-for-svm-faults.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/drm-nouveau-use-hmm_range_fault_unlocked_timeout-for-svm-faults.patch

This patch will later appear in the mm-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Before you just go and hit "reply", please:
   a) Consider who else should be cc'ed
   b) Prefer to cc a suitable mailing list as well
   c) Ideally: find the original patch on the mailing list and do a
      reply-to-all to that, adding suitable additional cc's

*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***

The -mm tree is included into linux-next via various
branches at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
and is updated there most days

------------------------------------------------------
From: Stanislav Kinsburskii <[email protected]>
Subject: drm/nouveau: use hmm_range_fault_unlocked_timeout() for SVM faults
Date: Thu, 23 Jul 2026 10:36:37 -0700

nouveau_range_fault() takes mmap_read_lock() only to call
hmm_range_fault().  It also keeps a single HMM_RANGE_DEFAULT_TIMEOUT
deadline across both HMM -EBUSY retries and post-fault
mmu_interval_read_retry() retries.

Use hmm_range_fault_unlocked_timeout() instead.  The HMM helper now owns
the mmap lock and refreshes range->notifier_seq for its internal retries. 
Nouveau keeps its existing absolute deadline in the outer loop and passes
the remaining jiffies to the helper for each fault attempt, so retries
caused by mmu_interval_read_retry() do not reset the overall retry budget.

Nouveau still validates the interval notifier sequence while holding
svmm->mutex before programming the GPU mapping.

Link: https://lore.kernel.org/[email protected]
Signed-off-by: Stanislav Kinsburskii <[email protected]>
Reviewed-by: Jason Gunthorpe <[email protected]>
Cc: Danilo Krummrich <[email protected]>
Cc: Dave Airlie <[email protected]>
Cc: David Hildenbrand <[email protected]>
Cc: Dexuan Cui <[email protected]>
Cc: Haiyang Zhang <[email protected]>
Cc: Jonathan Corbet <[email protected]>
Cc: K. Y. Srinivasan <[email protected]>
Cc: Leon Romanovsky <[email protected]>
Cc: Liam R. Howlett <[email protected]>
Cc: Lizhi Hou <[email protected]>
Cc: Long Li <[email protected]>
Cc: Lorenzo Stoakes <[email protected]>
Cc: Lyude <[email protected]>
Cc: Maarten Lankhorst <[email protected]>
Cc: Maxime Ripard <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: Mike Rapoport <[email protected]>
Cc: Oded Gabbay <[email protected]>
Cc: Shuah Khan <[email protected]>
Cc: Suren Baghdasaryan <[email protected]>
Cc: Thomas Zimemrmann <[email protected]>
Cc: Vlastimil Babka <[email protected]>
Cc: Wei Liu <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
---

 drivers/gpu/drm/nouveau/nouveau_svm.c |   20 +++++++++++---------
 1 file changed, 11 insertions(+), 9 deletions(-)

--- a/drivers/gpu/drm/nouveau/nouveau_svm.c~drm-nouveau-use-hmm_range_fault_unlocked_timeout-for-svm-faults
+++ a/drivers/gpu/drm/nouveau/nouveau_svm.c
@@ -678,20 +678,22 @@ static int nouveau_range_fault(struct no
 	range.end = notifier->notifier.interval_tree.last + 1;
 
 	while (true) {
-		if (time_after(jiffies, timeout)) {
+		long remaining = timeout - jiffies;
+
+		/*
+		 * The HMM timeout only bounds retries while HMM is walking and
+		 * faulting the range. This fault is handled by a kernel worker,
+		 * so fatal signals from the faulting process cannot stop an
+		 * endless stream of invalidations here.
+		 */
+		if (time_after_eq(jiffies, timeout)) {
 			ret = -EBUSY;
 			goto out;
 		}
 
-		range.notifier_seq = mmu_interval_read_begin(range.notifier);
-		mmap_read_lock(mm);
-		ret = hmm_range_fault(&range);
-		mmap_read_unlock(mm);
-		if (ret) {
-			if (ret == -EBUSY)
-				continue;
+		ret = hmm_range_fault_unlocked_timeout(&range, remaining);
+		if (ret)
 			goto out;
-		}
 
 		mutex_lock(&svmm->mutex);
 		if (mmu_interval_read_retry(range.notifier,
_

Patches currently in -mm which might be from [email protected] are

mm-hmm-move-page-fault-handling-out-of-walk-callbacks.patch
mm-hmm-add-hmm_range_fault_unlocked_timeout-for-mmap-lock-drop-support.patch
selftests-mm-add-hmm-test-for-mmap-lock-dropping-faults.patch
mshv-use-hmm_range_fault_unlocked_timeout-for-region-faults.patch
drm-nouveau-use-hmm_range_fault_unlocked_timeout-for-svm-faults.patch
rdma-umem-use-hmm_range_fault_unlocked_timeout-for-odp-faults.patch
accel-amdxdna-use-hmm_range_fault_unlocked_timeout-for-range-population.patch
drm-gpusvm-use-hmm_range_fault_unlocked_timeout-for-range-faults.patch