Author: markj Date: Mon Sep 7 23:28:33 2020 New Revision: 365437 URL: https://svnweb.freebsd.org/changeset/base/365437
Log: vm_object_split(): Handle orig_object type changes. orig_object->type can change from OBJT_DEFAULT to OBJT_SWAP while vm_object_split() is sleeping. In this case some pages in new_object may be left unbusied, but vm_object_split() attempts to unbusy all of them. Track the beginning of the busied range. Add an assertion to verify that pages are not re-added to the source object while sleeping. Reported by: Olympios Petrakis <[email protected]> Reviewed by: alc, kib Tested by: pho MFC after: 1 week Sponsored by: NetApp, Inc. Sponsored by: Klara, Inc. Differential Revision: https://reviews.freebsd.org/D26223 Modified: head/sys/vm/vm_object.c Modified: head/sys/vm/vm_object.c ============================================================================== --- head/sys/vm/vm_object.c Mon Sep 7 23:22:16 2020 (r365436) +++ head/sys/vm/vm_object.c Mon Sep 7 23:28:33 2020 (r365437) @@ -1496,7 +1496,7 @@ vm_object_shadow(vm_object_t *object, vm_ooffset_t *of void vm_object_split(vm_map_entry_t entry) { - vm_page_t m, m_next; + vm_page_t m, m_busy, m_next; vm_object_t orig_object, new_object, backing_object; vm_pindex_t idx, offidxstart; vm_size_t size; @@ -1553,8 +1553,14 @@ vm_object_split(vm_map_entry_t entry) * that the object is in transition. */ vm_object_set_flag(orig_object, OBJ_SPLIT); + m_busy = NULL; +#ifdef INVARIANTS + idx = 0; +#endif retry: m = vm_page_find_least(orig_object, offidxstart); + KASSERT(m == NULL || idx <= m->pindex - offidxstart, + ("%s: object %p was repopulated", __func__, orig_object)); for (; m != NULL && (idx = m->pindex - offidxstart) < size; m = m_next) { m_next = TAILQ_NEXT(m, listq); @@ -1609,8 +1615,15 @@ retry: */ vm_reserv_rename(m, new_object, orig_object, offidxstart); #endif + + /* + * orig_object's type may change while sleeping, so keep track + * of the beginning of the busied range. + */ if (orig_object->type != OBJT_SWAP) vm_page_xunbusy(m); + else if (m_busy == NULL) + m_busy = m; } if (orig_object->type == OBJT_SWAP) { /* @@ -1618,8 +1631,9 @@ retry: * and new_object's locks are released and reacquired. */ swap_pager_copy(orig_object, new_object, offidxstart, 0); - TAILQ_FOREACH(m, &new_object->memq, listq) - vm_page_xunbusy(m); + if (m_busy != NULL) + TAILQ_FOREACH_FROM(m_busy, &new_object->memq, listq) + vm_page_xunbusy(m_busy); } vm_object_clear_flag(orig_object, OBJ_SPLIT); VM_OBJECT_WUNLOCK(orig_object); _______________________________________________ [email protected] mailing list https://lists.freebsd.org/mailman/listinfo/svn-src-head To unsubscribe, send any mail to "[email protected]"
