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MSHV currently faults movable memory regions by taking mmap_read_lock() around hmm_range_fault(). That prevents the fault path from handling VMAs whose fault handlers need to drop mmap_lock, such as userfaultfd-backed mappings. Use hmm_range_fault_unlocked_timeout() instead. Passing a timeout of 0 preserves MSHV's existing unbounded retry behavior while letting the HMM helper own mmap_lock acquisition and refresh range->notifier_seq internally before walking the range. After the fault succeeds, MSHV still takes mreg_mutex and checks mmu_interval_read_retry() before installing the pages into the region, so the existing invalidation synchronization is preserved. Fold the small fault-and-lock helper into mshv_region_range_fault(), since the remaining retry path is just the standard "fault, take the driver lock, check the interval notifier sequence" pattern. Link: https://lore.kernel.org/20260723-hmm-v10-v11-4-c55b003a4b61@gmail.com Signed-off-by: Stanislav Kinsburskii <skinsburskii@gmail.com> Reviewed-by: Jason Gunthorpe <jgg@nvidia.com> Cc: Danilo Krummrich <dakr@kernel.org> Cc: Dave Airlie <airlied@gmail.com> Cc: David Hildenbrand <david@kernel.org> Cc: Dexuan Cui <decui@microsoft.com> Cc: Haiyang Zhang <haiyangz@microsoft.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: K. Y. Srinivasan <kys@microsoft.com> Cc: Leon Romanovsky <leon@kernel.org> Cc: Liam R. Howlett <liam@infradead.org> Cc: Lizhi Hou <lizhi.hou@amd.com> Cc: Long Li <longli@microsoft.com> Cc: Lorenzo Stoakes <ljs@kernel.org> Cc: Lyude <lyude@redhat.com> Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com> Cc: Maxime Ripard <mripard@kernel.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Mike Rapoport <rppt@kernel.org> Cc: Oded Gabbay <ogabbay@kernel.org> Cc: Shuah Khan <shuah@kernel.org> Cc: Suren Baghdasaryan <surenb@google.com> Cc: Thomas Zimemrmann <tzimmermann@suse.de> Cc: Vlastimil Babka <vbabka@kernel.org> Cc: Wei Liu <wei.liu@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>