Add the rt linux 4.1.3-rt3 as base

[kvmfornfv.git] / kernel / mm / debug-pagealloc.c

diff --git a/kernel/mm/debug-pagealloc.c b/kernel/mm/debug-pagealloc.c
new file mode 100644 (file)
index 0000000..5bf5906
--- /dev/null
+++ b/kernel/mm/debug-pagealloc.c
@@ -0,0 +1,137 @@
+#include <linux/kernel.h>
+#include <linux/string.h>
+#include <linux/mm.h>
+#include <linux/highmem.h>
+#include <linux/page_ext.h>
+#include <linux/poison.h>
+#include <linux/ratelimit.h>
+
+static bool page_poisoning_enabled __read_mostly;
+
+static bool need_page_poisoning(void)
+{
+       if (!debug_pagealloc_enabled())
+               return false;
+
+       return true;
+}
+
+static void init_page_poisoning(void)
+{
+       if (!debug_pagealloc_enabled())
+               return;
+
+       page_poisoning_enabled = true;
+}
+
+struct page_ext_operations page_poisoning_ops = {
+       .need = need_page_poisoning,
+       .init = init_page_poisoning,
+};
+
+static inline void set_page_poison(struct page *page)
+{
+       struct page_ext *page_ext;
+
+       page_ext = lookup_page_ext(page);
+       __set_bit(PAGE_EXT_DEBUG_POISON, &page_ext->flags);
+}
+
+static inline void clear_page_poison(struct page *page)
+{
+       struct page_ext *page_ext;
+
+       page_ext = lookup_page_ext(page);
+       __clear_bit(PAGE_EXT_DEBUG_POISON, &page_ext->flags);
+}
+
+static inline bool page_poison(struct page *page)
+{
+       struct page_ext *page_ext;
+
+       page_ext = lookup_page_ext(page);
+       return test_bit(PAGE_EXT_DEBUG_POISON, &page_ext->flags);
+}
+
+static void poison_page(struct page *page)
+{
+       void *addr = kmap_atomic(page);
+
+       set_page_poison(page);
+       memset(addr, PAGE_POISON, PAGE_SIZE);
+       kunmap_atomic(addr);
+}
+
+static void poison_pages(struct page *page, int n)
+{
+       int i;
+
+       for (i = 0; i < n; i++)
+               poison_page(page + i);
+}
+
+static bool single_bit_flip(unsigned char a, unsigned char b)
+{
+       unsigned char error = a ^ b;
+
+       return error && !(error & (error - 1));
+}
+
+static void check_poison_mem(unsigned char *mem, size_t bytes)
+{
+       static DEFINE_RATELIMIT_STATE(ratelimit, 5 * HZ, 10);
+       unsigned char *start;
+       unsigned char *end;
+
+       start = memchr_inv(mem, PAGE_POISON, bytes);
+       if (!start)
+               return;
+
+       for (end = mem + bytes - 1; end > start; end--) {
+               if (*end != PAGE_POISON)
+                       break;
+       }
+
+       if (!__ratelimit(&ratelimit))
+               return;
+       else if (start == end && single_bit_flip(*start, PAGE_POISON))
+               printk(KERN_ERR "pagealloc: single bit error\n");
+       else
+               printk(KERN_ERR "pagealloc: memory corruption\n");
+
+       print_hex_dump(KERN_ERR, "", DUMP_PREFIX_ADDRESS, 16, 1, start,
+                       end - start + 1, 1);
+       dump_stack();
+}
+
+static void unpoison_page(struct page *page)
+{
+       void *addr;
+
+       if (!page_poison(page))
+               return;
+
+       addr = kmap_atomic(page);
+       check_poison_mem(addr, PAGE_SIZE);
+       clear_page_poison(page);
+       kunmap_atomic(addr);
+}
+
+static void unpoison_pages(struct page *page, int n)
+{
+       int i;
+
+       for (i = 0; i < n; i++)
+               unpoison_page(page + i);
+}
+
+void __kernel_map_pages(struct page *page, int numpages, int enable)
+{
+       if (!page_poisoning_enabled)
+               return;
+
+       if (enable)
+               unpoison_pages(page, numpages);
+       else
+               poison_pages(page, numpages);
+}