When a vnode-backed vm object is referenced, it increments the vnode
reference count, and decrements it on dereference. If referenced object is deallocated, object type is reset to OBJT_DEAD. Consequently, all vnode references that are owned by object references are never released. vunref() the vnode in vm object deallocation code for OBJT_VNODE appropriate number of times to prevent leak. Add an assertion to the vm_pageout() to make sure that we never get reference on the vnode but then do not execute code to release it. In collaboration with: pho Reviewed by: alc MFC after: 3 weeks
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Notes:
svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=202529
@ -951,6 +951,8 @@ vm_pageout_scan(int pass)
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vnodes_skipped++;
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goto unlock_and_continue;
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}
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KASSERT(mp != NULL,
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("vp %p with NULL v_mount", vp));
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vm_page_unlock_queues();
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vm_object_reference_locked(object);
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VM_OBJECT_UNLOCK(object);
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@ -250,13 +250,16 @@ static void
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vnode_pager_dealloc(object)
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vm_object_t object;
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{
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struct vnode *vp = object->handle;
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struct vnode *vp;
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int refs;
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vp = object->handle;
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if (vp == NULL)
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panic("vnode_pager_dealloc: pager already dealloced");
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VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
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vm_object_pip_wait(object, "vnpdea");
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refs = object->ref_count;
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object->handle = NULL;
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object->type = OBJT_DEAD;
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@ -267,6 +270,8 @@ vnode_pager_dealloc(object)
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ASSERT_VOP_ELOCKED(vp, "vnode_pager_dealloc");
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vp->v_object = NULL;
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vp->v_vflag &= ~VV_TEXT;
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while (refs-- > 0)
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vunref(vp);
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}
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static boolean_t
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