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In the Linux kernel, the following vulnerability has been resolved: mm: Fix a hmm_range_fault() livelock / starvation problem If hmm_range_fault() fails a folio_trylock() in do_swap_page, trying to acquire the lock of a device-private folio for migration, to ram, the function will spin until it succeeds grabbing the lock. However, if the process holding the lock is depending on a work item to be completed, which is scheduled on the same CPU as the spinning hmm_range_fault(), that work item might be starved and we end up in a livelock / starvation situation which is never resolved. This can happen, for example if the process holding the device-private folio lock is stuck in migrate_device_unmap()->lru_add_drain_all() sinc lru_add_drain_all() requires a short work-item to be run on all online cpus to complete. A prerequisite for this to happen is: a) Both zone device and system memory folios are considered in migrate_device_unmap(), so that there is a reason to call lru_add_drain_all() for a system memory folio while a folio lock is held on a zone device folio. b) The zone device folio has an initial mapcount > 1 which causes at least one migration PTE entry insertion to be deferred to try_to_migrate(), which can happen after the call to lru_add_drain_all(). c) No or voluntary only preemption. This all seems pretty unlikely to happen, but indeed is hit by the "xe_exec_system_allocator" igt test. Resolve this by waiting for the folio to be unlocked if the folio_trylock() fails in do_swap_page(). Rename migration_entry_wait_on_locked() to softleaf_entry_wait_unlock() and update its documentation to indicate the new use-case. Future code improvements might consider moving the lru_add_drain_all() call in migrate_device_unmap() to be called *after* all pages have migration entries inserted. That would eliminate also b) above. v2: - Instead of a cond_resched() in hmm_range_fault(), eliminate the problem by waiting for the folio to be unlocke
Засегнати продукти
- Linux Linux: 1afaeb8293c9addbf4f9140bdd22635fed763459 преди 94b6d0ba4b640ba23bb6c708a59316e74e5ede63; 1afaeb8293c9addbf4f9140bdd22635fed763459 преди 7e6e2fc91d4b9b12ec6e137019532568ebcf2680; 1afaeb8293c9addbf4f9140bdd22635fed763459 преди b570f37a2ce480be26c665345c5514686a8a0274
- Linux Linux: 6.15; преди 6.15; 6.18.19 до 6.18.*; 6.19.9 до 6.19.*; от 7.0 нататък
История
- 8 май 2026 Публикувано
Други уязвимости в Linux Linux
Първоизточници
- https://www.cve.org/CVERecord?id=CVE-2026-43404
- https://nvd.nist.gov/vuln/detail/CVE-2026-43404
- https://git.kernel.org/stable/c/94b6d0ba4b640ba23bb6c708a59316e74e5ede63
- https://git.kernel.org/stable/c/7e6e2fc91d4b9b12ec6e137019532568ebcf2680
- https://git.kernel.org/stable/c/b570f37a2ce480be26c665345c5514686a8a0274