2 files changed, 14 insertions, 2 deletions

diff --git a/drivers/char/tty_buffer.c b/drivers/char/tty_buffer.c
index 66fa4e10d76b..f27c4d6d956e 100644
--- a/drivers/char/tty_buffer.c
+++ b/drivers/char/tty_buffer.c
@@ -247,7 +247,8 @@ int tty_insert_flip_string(struct tty_struct *tty, const unsigned char *chars,
 {
         int copied = 0;
         do {
-                int space = tty_buffer_request_room(tty, size - copied);
+                int goal = min(size - copied, TTY_BUFFER_PAGE);
+                int space = tty_buffer_request_room(tty, goal);
                 struct tty_buffer *tb = tty->buf.tail;
                 /* If there is no space then tb may be NULL */
                 if (unlikely(space == 0))
@@ -283,7 +284,8 @@ int tty_insert_flip_string_flags(struct tty_struct *tty,
 {
         int copied = 0;
         do {
-                int space = tty_buffer_request_room(tty, size - copied);
+                int goal = min(size - copied, TTY_BUFFER_PAGE);
+                int space = tty_buffer_request_room(tty, goal);
                 struct tty_buffer *tb = tty->buf.tail;
                 /* If there is no space then tb may be NULL */
                 if (unlikely(space == 0))
diff --git a/include/linux/tty.h b/include/linux/tty.h
index 6abfcf5b5887..d96e5882f129 100644
--- a/include/linux/tty.h
+++ b/include/linux/tty.h
@@ -68,6 +68,16 @@ struct tty_buffer {
         unsigned long data[0];
 };
 
+/*
+ * We default to dicing tty buffer allocations to this many characters
+ * in order to avoid multiple page allocations. We assume tty_buffer itself
+ * is under 256 bytes. See tty_buffer_find for the allocation logic this
+ * must match
+ */
+
+#define TTY_BUFFER_PAGE         ((PAGE_SIZE  - 256) / 2)
+
+
 struct tty_bufhead {
         struct delayed_work work;
         spinlock_t lock;