[PATCH 27/46] mm/mmu_notifier: finish non-blocking interval invalidation on error

[sashiko-bot at kernel.org]

> From: Josef Bacik <josef at toxicpanda.com>
> 
> When an ordinary MMU notifier rejects a non-blocking invalidation, the
> interval invalidation started beforehand is left unfinished: the caller
> skips mmu_notifier_invalidate_range_end(). Subsequent interval notifier
> operations can then wait forever.
> 
> The only in-tree trigger is nouveau SVM, which uses both notifier types
> and rejects non-blocking invalidations. Reaping via the OOM reaper or
> process_mrelease() can therefore leave the GPU fault worker stuck,
> holding a reference that prevents the dying process's address space
> and memory from being freed.
> 
> End the interval invalidation when an ordinary notifier fails a
> non-blocking invalidation, like mn_itree_invalidate() already does when
> an interval notifier fails. Make that handling clearer in the
> documentation of mmu_notifier_invalidate_range_start_nonblock().
> 
> Fix generated by an LLM and sent by Josef Bacik in private.
> 
> Fixes: 99cb252f5e68 ("mm/mmu_notifier: add an interval tree notifier")
> Cc: stable at vger.kernel.org
> Signed-off-by: Josef Bacik <josef at toxicpanda.com>
> [ david: simplify description, update function doc ]
> Signed-off-by: David Hildenbrand (Arm) <david at kernel.org>

Sashiko has reviewed this patch and found no issues.

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Sashiko AI review · https://sashiko.dev/#/patchset/20261027-fixes_core-v1-0-6f74bec9a5bb@kernel.org?part=27