Addendum to r254141: The call to vm_radix_insert() in vm_page_cache() can
reclaim the last preexisting cached page in the object, resulting in a call to vdrop(). Detect this scenario so that the vnode's hold count is correctly maintained. Otherwise, we panic. Reported by: scottl Tested by: pho Discussed with: attilio, jeff, kib
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Notes:
svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=254719
@ -2558,6 +2558,15 @@ vm_page_cache(vm_page_t m)
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vm_page_free(m);
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return;
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}
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/*
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* The above call to vm_radix_insert() could reclaim the one pre-
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* existing cached page from this object, resulting in a call to
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* vdrop().
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*/
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if (!cache_was_empty)
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cache_was_empty = vm_radix_is_singleton(&object->cache);
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m->flags |= PG_CACHED;
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cnt.v_cache_count++;
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PCPU_INC(cnt.v_tcached);
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@ -431,6 +431,21 @@ vm_radix_insert(struct vm_radix *rtree, vm_page_t page)
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return (0);
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}
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/*
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* Returns TRUE if the specified radix tree contains a single leaf and FALSE
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* otherwise.
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*/
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boolean_t
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vm_radix_is_singleton(struct vm_radix *rtree)
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{
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struct vm_radix_node *rnode;
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rnode = vm_radix_getroot(rtree);
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if (rnode == NULL)
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return (FALSE);
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return (vm_radix_isleaf(rnode));
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}
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/*
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* Returns the value stored at the index. If the index is not present,
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* NULL is returned.
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@ -37,6 +37,7 @@
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void vm_radix_init(void);
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int vm_radix_insert(struct vm_radix *rtree, vm_page_t page);
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boolean_t vm_radix_is_singleton(struct vm_radix *rtree);
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vm_page_t vm_radix_lookup(struct vm_radix *rtree, vm_pindex_t index);
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vm_page_t vm_radix_lookup_ge(struct vm_radix *rtree, vm_pindex_t index);
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vm_page_t vm_radix_lookup_le(struct vm_radix *rtree, vm_pindex_t index);
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