1 files changed, 20 insertions, 29 deletions

diff --git a/mm/swapfile.c b/mm/swapfile.c
index ff8dc1a18cb..17bc224bce6 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -1681,19 +1681,14 @@ out:
 }
 
 #ifdef CONFIG_PROC_FS
-struct proc_swaps {
-        struct seq_file seq;
-        int event;
-};
-
 static unsigned swaps_poll(struct file *file, poll_table *wait)
 {
-        struct proc_swaps *s = file->private_data;
+        struct seq_file *seq = file->private_data;
 
         poll_wait(file, &proc_poll_wait, wait);
 
-        if (s->event != atomic_read(&proc_poll_event)) {
-                s->event = atomic_read(&proc_poll_event);
+        if (seq->poll_event != atomic_read(&proc_poll_event)) {
+                seq->poll_event = atomic_read(&proc_poll_event);
                 return POLLIN | POLLRDNORM | POLLERR | POLLPRI;
         }
 
@@ -1783,24 +1778,16 @@ static const struct seq_operations swaps_op = {
 
 static int swaps_open(struct inode *inode, struct file *file)
 {
-        struct proc_swaps *s;
+        struct seq_file *seq;
         int ret;
 
-        s = kmalloc(sizeof(struct proc_swaps), GFP_KERNEL);
-        if (!s)
-                return -ENOMEM;
-
-        file->private_data = s;
-
         ret = seq_open(file, &swaps_op);
-        if (ret) {
-                kfree(s);
+        if (ret)
                 return ret;
-        }
 
-        s->seq.private = s;
-        s->event = atomic_read(&proc_poll_event);
-        return ret;
+        seq = file->private_data;
+        seq->poll_event = atomic_read(&proc_poll_event);
+        return 0;
 }
 
 static const struct file_operations proc_swaps_operations = {
@@ -1937,20 +1924,24 @@ static unsigned long read_swap_header(struct swap_info_struct *p,
 
         /*
          * Find out how many pages are allowed for a single swap
-         * device. There are two limiting factors: 1) the number of
-         * bits for the swap offset in the swp_entry_t type and
-         * 2) the number of bits in the a swap pte as defined by
-         * the different architectures. In order to find the
-         * largest possible bit mask a swap entry with swap type 0
+         * device. There are three limiting factors: 1) the number
+         * of bits for the swap offset in the swp_entry_t type, and
+         * 2) the number of bits in the swap pte as defined by the
+         * the different architectures, and 3) the number of free bits
+         * in an exceptional radix_tree entry. In order to find the
+         * largest possible bit mask, a swap entry with swap type 0
          * and swap offset ~0UL is created, encoded to a swap pte,
-         * decoded to a swp_entry_t again and finally the swap
+         * decoded to a swp_entry_t again, and finally the swap
          * offset is extracted. This will mask all the bits from
          * the initial ~0UL mask that can't be encoded in either
          * the swp_entry_t or the architecture definition of a
-         * swap pte.
+         * swap pte.  Then the same is done for a radix_tree entry.
          */
         maxpages = swp_offset(pte_to_swp_entry(
-                        swp_entry_to_pte(swp_entry(0, ~0UL)))) + 1;
+                        swp_entry_to_pte(swp_entry(0, ~0UL))));
+        maxpages = swp_offset(radix_to_swp_entry(
+                        swp_to_radix_entry(swp_entry(0, maxpages)))) + 1;
+
         if (maxpages > swap_header->info.last_page) {
                 maxpages = swap_header->info.last_page + 1;
                 /* p->max is an unsigned int: don't overflow it */