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| author |   Kees Cook <keescook@chromium.org> | 2020-06-03 13:28:45 -0700 |
|---|---|---|
| committer | Kees Cook <keescook@chromium.org> | 2020-07-16 12:32:25 -0700 |
| commit | aecfd220b223043475fa515aa563249f683fcd04 (patch) | |
| tree | 0b1add5f2d86a4707d42501aab3efcb661c371c2 | |
| parent | docs: deprecated.rst: Add uninitialized_var() (diff) | |
| download | linux-dev-aecfd220b223043475fa515aa563249f683fcd04.tar.xz linux-dev-aecfd220b223043475fa515aa563249f683fcd04.zip | |
x86/mm/numa: Remove uninitialized_var() usage
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>
| -rw-r--r-- | arch/x86/mm/numa.c | 18 | ||||
| -rw-r--r-- | include/linux/page-flags-layout.h | 4 |
2 files changed, 12 insertions, 10 deletions
diff --git a/arch/x86/mm/numa.c b/arch/x86/mm/numa.c index 8ee952038c80..b05f45e5e8e2 100644 --- a/arch/x86/mm/numa.c +++ b/arch/x86/mm/numa.c @@ -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; diff --git a/include/linux/page-flags-layout.h b/include/linux/page-flags-layout.h index 71283739ffd2..e200eef6a7fd 100644 --- a/include/linux/page-flags-layout.h +++ b/include/linux/page-flags-layout.h @@ -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 |