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Olivier Certner
b15ff72140
All iterators that rely on an object's 'struct domainset_ref' (field 'domain' on 'struct vm_object'), which is the case for page allocations with objects, are used with the corresponding object locked for writing, so cannot lose concurrent iterator index's increases even if those are made without atomic operations. The only offender was thread stack allocation, which has just been fixed in commit3b9b644576("vm: Fix iterator usage in vm_thread_stack_create()"). However, the interleaved policy would still reset the iterator index when restarting, losing track of the next domain to allocate from when applying round-robin, which all allocation policies do if allocation from the first domain fails. Fix this last round-robin problem by not resetting the shared index at iterator's phase init on DOMAINSET_POLICY_INTERLEAVE. Add an assertion to check that, when passed, an object is write-locked in order to prevent the problem mentioned in the first paragraph from reappearing. Approved by: re (cperciva) Reviewed by: markj MFC after: 1 week Sponsored by: The FreeBSD Foundation Differential Revision: https://reviews.freebsd.org/D52733 (cherry picked from commit7b0fe2d405) (cherry picked from commitd7226d1858)