[PATCH] tty/vt: avoid high order pages allocation on GIO_UNIMAP ioctl

[Konstantin Khorenko]

GIO_UNIMAP can easily result in a high order allocation,
seen 6th order allocation on radeondrmfb:

  fbcon: radeondrmfb (fb0) is primary device
  Console: switching to colour frame buffer device 160x64
  radeon 0000:01:05.0: fb0: radeondrmfb frame buffer device
  WARNING: CPU: 0 PID: 78661 at mm/page_alloc.c:3532
        __alloc_pages_nodemask+0x1b1/0x600
  order 6 >= 3, gfp 0x40d0

The warning is generated by a debug patch.

At the same time it's safe to use kvmalloc() for allocation in
con_get_unimap(), so let's do the substitution.

And do the same for con_set_unimap().

Signed-off-by: Konstantin Khorenko <khore...@virtuozzo.com>
---
 drivers/tty/vt/consolemap.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/tty/vt/consolemap.c b/drivers/tty/vt/consolemap.c
index 7c7ada0b3ea0..b28aa0d289f8 100644
--- a/drivers/tty/vt/consolemap.c
+++ b/drivers/tty/vt/consolemap.c
@@ -542,7 +542,7 @@ int con_set_unimap(struct vc_data *vc, ushort ct, struct 
unipair __user *list)
        if (!ct)
                return 0;
 
-       unilist = memdup_user(list, ct * sizeof(struct unipair));
+       unilist = vmemdup_user(list, ct * sizeof(struct unipair));
        if (IS_ERR(unilist))
                return PTR_ERR(unilist);
 
@@ -641,7 +641,7 @@ int con_set_unimap(struct vc_data *vc, ushort ct, struct 
unipair __user *list)
 
 out_unlock:
        console_unlock();
-       kfree(unilist);
+       kvfree(unilist);
        return err;
 }
 
@@ -743,7 +743,7 @@ int con_get_unimap(struct vc_data *vc, ushort ct, ushort 
__user *uct, struct uni
        struct uni_pagedir *p;
        struct unipair *unilist;
 
-       unilist = kmalloc_array(ct, sizeof(struct unipair), GFP_KERNEL);
+       unilist = kvmalloc_array(ct, sizeof(struct unipair), GFP_KERNEL);
        if (!unilist)
                return -ENOMEM;
 
@@ -775,7 +775,7 @@ int con_get_unimap(struct vc_data *vc, ushort ct, ushort 
__user *uct, struct uni
        if (copy_to_user(list, unilist, min(ect, ct) * sizeof(struct unipair)))
                ret = -EFAULT;
        put_user(ect, uct);
-       kfree(unilist);
+       kvfree(unilist);
        return ret ? ret : (ect <= ct) ? 0 : -ENOMEM;
 }
 
-- 
2.15.1