1 files changed, 83 insertions, 1 deletions

diff --git a/fs/proc/proc_misc.c b/fs/proc/proc_misc.c
index 19b69f931bef..fd751ea37fce 100644
--- a/fs/proc/proc_misc.c
+++ b/fs/proc/proc_misc.c
@@ -699,7 +699,10 @@ static ssize_t kpagecount_read(struct file *file, char __user *buf,
                 return -EIO;
 
         while (count > 0) {
-                ppage = pfn_to_page(pfn++);
+                ppage = NULL;
+                if (pfn_valid(pfn))
+                        ppage = pfn_to_page(pfn);
+                pfn++;
                 if (!ppage)
                         pcount = 0;
                 else
@@ -724,6 +727,84 @@ static struct file_operations proc_kpagecount_operations = {
         .read = kpagecount_read,
 };
 
+/* /proc/kpageflags - an array exposing page flags
+ *
+ * Each entry is a u64 representing the corresponding
+ * physical page flags.
+ */
+
+/* These macros are used to decouple internal flags from exported ones */
+
+#define KPF_LOCKED     0
+#define KPF_ERROR      1
+#define KPF_REFERENCED 2
+#define KPF_UPTODATE   3
+#define KPF_DIRTY      4
+#define KPF_LRU        5
+#define KPF_ACTIVE     6
+#define KPF_SLAB       7
+#define KPF_WRITEBACK  8
+#define KPF_RECLAIM    9
+#define KPF_BUDDY     10
+
+#define kpf_copy_bit(flags, srcpos, dstpos) (((flags >> srcpos) & 1) << dstpos)
+
+static ssize_t kpageflags_read(struct file *file, char __user *buf,
+                             size_t count, loff_t *ppos)
+{
+        u64 __user *out = (u64 __user *)buf;
+        struct page *ppage;
+        unsigned long src = *ppos;
+        unsigned long pfn;
+        ssize_t ret = 0;
+        u64 kflags, uflags;
+
+        pfn = src / KPMSIZE;
+        count = min_t(unsigned long, count, (max_pfn * KPMSIZE) - src);
+        if (src & KPMMASK || count & KPMMASK)
+                return -EIO;
+
+        while (count > 0) {
+                ppage = NULL;
+                if (pfn_valid(pfn))
+                        ppage = pfn_to_page(pfn);
+                pfn++;
+                if (!ppage)
+                        kflags = 0;
+                else
+                        kflags = ppage->flags;
+
+                uflags = kpf_copy_bit(KPF_LOCKED, PG_locked, kflags) |
+                        kpf_copy_bit(kflags, KPF_ERROR, PG_error) |
+                        kpf_copy_bit(kflags, KPF_REFERENCED, PG_referenced) |
+                        kpf_copy_bit(kflags, KPF_UPTODATE, PG_uptodate) |
+                        kpf_copy_bit(kflags, KPF_DIRTY, PG_dirty) |
+                        kpf_copy_bit(kflags, KPF_LRU, PG_lru) |
+                        kpf_copy_bit(kflags, KPF_ACTIVE, PG_active) |
+                        kpf_copy_bit(kflags, KPF_SLAB, PG_slab) |
+                        kpf_copy_bit(kflags, KPF_WRITEBACK, PG_writeback) |
+                        kpf_copy_bit(kflags, KPF_RECLAIM, PG_reclaim) |
+                        kpf_copy_bit(kflags, KPF_BUDDY, PG_buddy);
+
+                if (put_user(uflags, out++)) {
+                        ret = -EFAULT;
+                        break;
+                }
+
+                count -= KPMSIZE;
+        }
+
+        *ppos += (char __user *)out - buf;
+        if (!ret)
+                ret = (char __user *)out - buf;
+        return ret;
+}
+
+static struct file_operations proc_kpageflags_operations = {
+        .llseek = mem_lseek,
+        .read = kpageflags_read,
+};
+
 struct proc_dir_entry *proc_root_kcore;
 
 void create_seq_entry(char *name, mode_t mode, const struct file_operations *f)
@@ -805,6 +886,7 @@ void __init proc_misc_init(void)
         }
 #endif
         create_seq_entry("kpagecount", S_IRUSR, &proc_kpagecount_operations);
+        create_seq_entry("kpageflags", S_IRUSR, &proc_kpageflags_operations);
 #ifdef CONFIG_PROC_VMCORE
         proc_vmcore = create_proc_entry("vmcore", S_IRUSR, NULL);
         if (proc_vmcore)