Hello Johannes Weiner,
The patch 449dd6984d0e: "mm: keep page cache radix tree nodes in
check" from Apr 3, 2014, leads to the following static checker
warning:
mm/filemap.c:138 page_cache_tree_delete()
error: potentially using uninitialized 'node'.
mm/filemap.c
113 static void page_cache_tree_delete(struct address_space *mapping,
114 struct page *page, void *shadow)
115 {
116 struct radix_tree_node *node;
^^^^
117 unsigned long index;
118 unsigned int offset;
119 unsigned int tag;
120 void **slot;
121
122 VM_BUG_ON(!PageLocked(page));
123
124 __radix_tree_lookup(&mapping->page_tree, page->index, &node, &slot);
^^^^
125
126 if (shadow) {
127 mapping->nrexceptional++;
128 /*
129 * Make sure the nrexceptional update is committed before
130 * the nrpages update so that final truncate racing
131 * with reclaim does not see both counters 0 at the
132 * same time and miss a shadow entry.
133 */
134 smp_wmb();
135 }
136 mapping->nrpages--;
137
138 if (!node) {
^^^^
139 /* Clear direct pointer tags in root node */
140 mapping->page_tree.gfp_mask &= __GFP_BITS_MASK;
141 radix_tree_replace_slot(slot, shadow);
142 return;
143 }
It's obviously simple enough for me to initialize "node" to NULL but I
suspect there is a reason that it can't be uninitialized... I'm trying
to get some feedback for some new Smatch stuff I'm working on.
regards,
dan carpenter
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