@@ -543,7 +543,6 @@ static void __init numa_clear_kernel_node_hotplug(void)
static int __init numa_register_memblks(struct numa_meminfo *mi)
{
- unsigned long uninitialized_var(pfn_align);
int i, nid;
/* Account for nodes with cpus and no memory */
@@ -571,15 +570,16 @@ static int __init numa_register_memblks(struct numa_meminfo *mi)
* If sections array is gonna be used for pfn -> nid mapping, check
* whether its granularity is fine enough.
*/
-#ifdef NODE_NOT_IN_PAGE_FLAGS
- pfn_align = node_map_pfn_alignment();
- if (pfn_align && pfn_align < PAGES_PER_SECTION) {
- printk(KERN_WARNING "Node alignment %LuMB < min %LuMB, rejecting NUMA config\n",
- PFN_PHYS(pfn_align) >> 20,
- PFN_PHYS(PAGES_PER_SECTION) >> 20);
- return -EINVAL;
+ if (IS_ENABLED(NODE_NOT_IN_PAGE_FLAGS)) {
+ unsigned long pfn_align = node_map_pfn_alignment();
+
+ if (pfn_align && pfn_align < PAGES_PER_SECTION) {
+ pr_warn("Node alignment %LuMB < min %LuMB, rejecting NUMA config\n",
+ PFN_PHYS(pfn_align) >> 20,
+ PFN_PHYS(PAGES_PER_SECTION) >> 20);
+ return -EINVAL;
+ }
}
-#endif
if (!numa_meminfo_cover_memory(mi))
return -EINVAL;
@@ -98,9 +98,11 @@
/*
* We are going to use the flags for the page to node mapping if its in
* there. This includes the case where there is no node, so it is implicit.
+ * Note that this #define MUST have a value so that it can be tested with
+ * the IS_ENABLED() macro.
*/
#if !(NODES_WIDTH > 0 || NODES_SHIFT == 0)
-#define NODE_NOT_IN_PAGE_FLAGS
+#define NODE_NOT_IN_PAGE_FLAGS 1
#endif
#if defined(CONFIG_NUMA_BALANCING) && LAST_CPUPID_WIDTH == 0
Using uninitialized_var() is dangerous as it papers over real bugs[1] (or can in the future), and suppresses unrelated compiler warnings (e.g. "unused variable"). If the compiler thinks it is uninitialized, either simply initialize the variable or make compiler changes. As a precursor to removing[2] this[3] macro[4], refactor code to avoid its need. The original reason for its use here was to work around the #ifdef being the only place the variable was used. This is better expressed using IS_ENABLED() and a new code block where the variable can be used unconditionally. [1] https://lore.kernel.org/lkml/20200603174714.192027-1-glider@google.com/ [2] https://lore.kernel.org/lkml/CA+55aFw+Vbj0i=1TGqCR5vQkCzWJ0QxK6CernOU6eedsudAixw@mail.gmail.com/ [3] https://lore.kernel.org/lkml/CA+55aFwgbgqhbp1fkxvRKEpzyR5J8n1vKT1VZdz9knmPuXhOeg@mail.gmail.com/ [4] https://lore.kernel.org/lkml/CA+55aFz2500WfbKXAx8s67wrm9=yVJu65TpLgN_ybYNv0VEOKA@mail.gmail.com/ Fixes: 1e01979c8f50 ("x86, numa: Implement pfn -> nid mapping granularity check") Signed-off-by: Kees Cook <keescook@chromium.org> --- arch/x86/mm/numa.c | 18 +++++++++--------- include/linux/page-flags-layout.h | 4 +++- 2 files changed, 12 insertions(+), 10 deletions(-)