5 files changed, 69 insertions, 6 deletions

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 8022d902e770..dcd082576e79 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -4839,6 +4839,18 @@
                         This is actually a boot loader parameter; the value is
                         passed to the kernel using a special protocol.
 
+        vm_debug[=options]      [KNL] Available with CONFIG_DEBUG_VM=y.
+                        May slow down system boot speed, especially when
+                        enabled on systems with a large amount of memory.
+                        All options are enabled by default, and this
+                        interface is meant to allow for selectively
+                        enabling or disabling specific virtual memory
+                        debugging features.
+
+                        Available options are:
+                          P     Enable page structure init time poisoning
+                          -     Disable all of the above options
+
         vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
                         size of <nn>. This can be used to increase the
                         minimum size (128MB on x86). It can also be used to
diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h
index 4d99504f6496..934f91ef3f54 100644
--- a/include/linux/page-flags.h
+++ b/include/linux/page-flags.h
@@ -163,6 +163,14 @@ static inline int PagePoisoned(const struct page *page)
         return page->flags == PAGE_POISON_PATTERN;
 }
 
+#ifdef CONFIG_DEBUG_VM
+void page_init_poison(struct page *page, size_t size);
+#else
+static inline void page_init_poison(struct page *page, size_t size)
+{
+}
+#endif
+
 /*
  * Page flags policies wrt compound pages
  *
diff --git a/mm/debug.c b/mm/debug.c
index bd10aad8539a..cdacba12e09a 100644
--- a/mm/debug.c
+++ b/mm/debug.c
@@ -13,6 +13,7 @@
 #include <trace/events/mmflags.h>
 #include <linux/migrate.h>
 #include <linux/page_owner.h>
+#include <linux/ctype.h>
 
 #include "internal.h"
 
@@ -175,4 +176,49 @@ void dump_mm(const struct mm_struct *mm)
         );
 }
 
+static bool page_init_poisoning __read_mostly = true;
+
+static int __init setup_vm_debug(char *str)
+{
+        bool __page_init_poisoning = true;
+
+        /*
+         * Calling vm_debug with no arguments is equivalent to requesting
+         * to enable all debugging options we can control.
+         */
+        if (*str++ != '=' || !*str)
+                goto out;
+
+        __page_init_poisoning = false;
+        if (*str == '-')
+                goto out;
+
+        while (*str) {
+                switch (tolower(*str)) {
+                case'p':
+                        __page_init_poisoning = true;
+                        break;
+                default:
+                        pr_err("vm_debug option '%c' unknown. skipped\n",
+                               *str);
+                }
+
+                str++;
+        }
+out:
+        if (page_init_poisoning && !__page_init_poisoning)
+                pr_warn("Page struct poisoning disabled by kernel command line option 'vm_debug'\n");
+
+        page_init_poisoning = __page_init_poisoning;
+
+        return 1;
+}
+__setup("vm_debug", setup_vm_debug);
+
+void page_init_poison(struct page *page, size_t size)
+{
+        if (page_init_poisoning)
+                memset(page, PAGE_POISON_PATTERN, size);
+}
+EXPORT_SYMBOL_GPL(page_init_poison);
 #endif          /* CONFIG_DEBUG_VM */
diff --git a/mm/memblock.c b/mm/memblock.c
index 237944479d25..a85315083b5a 100644
--- a/mm/memblock.c
+++ b/mm/memblock.c
@@ -1444,10 +1444,9 @@ void * __init memblock_virt_alloc_try_nid_raw(
 
         ptr = memblock_virt_alloc_internal(size, align,
                                            min_addr, max_addr, nid);
-#ifdef CONFIG_DEBUG_VM
         if (ptr && size > 0)
-                memset(ptr, PAGE_POISON_PATTERN, size);
-#endif
+                page_init_poison(ptr, size);
+
         return ptr;
 }
 
diff --git a/mm/sparse.c b/mm/sparse.c
index 10b07eea9a6e..67ad061f7fb8 100644
--- a/mm/sparse.c
+++ b/mm/sparse.c
@@ -696,13 +696,11 @@ int __meminit sparse_add_one_section(struct pglist_data *pgdat,
                 goto out;
         }
 
-#ifdef CONFIG_DEBUG_VM
         /*
          * Poison uninitialized struct pages in order to catch invalid flags
          * combinations.
          */
-        memset(memmap, PAGE_POISON_PATTERN, sizeof(struct page) * PAGES_PER_SECTION);
-#endif
+        page_init_poison(memmap, sizeof(struct page) * PAGES_PER_SECTION);
 
         section_mark_present(ms);
         sparse_init_one_section(ms, section_nr, memmap, usemap);